Spectroscopy 1012 2012

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October 2012 Volume 27 Number 10 www.spectroscopyonline.com

Making Images at the Speed of Light

FT-IR Imaging for Label-Free Chemical Detection in

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Observing Heterogeneous Catalysts with Operando

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CONTENTS

Spectroscopy (ISSN 0887-6703 [print], ISSN 1939-1900 [digital]) is published monthly by Advanstar Communications, Inc., 131 West First Street, Duluth, MN 55802-2065. Spectroscopy is distributed free of charge to users and specifiers of spectroscopic equipment in the United States. Spectroscopy is available on a paid subscription basis to nonqualified readers at the rate of: U.S. and possessions: 1 year (12 issues), $74.95; 2 years (24 issues), $134.50. Canada/Mexico: 1 year, $95; 2 years, $150. International: 1 year (12 issues), $140; 2 years (24 issues), $250. Periodicals postage paid at Duluth, MN 55806 and at additional mailing of fices. POSTMASTER: Send address changes to Spectroscopy, P.O. Box 6196, Duluth, MN 55806-6196. PUBLICATIONS MAIL AGREEMENT NO. 40612608, Return Undeliverable Canadian Addresses to: Pitney Bowes, P. O. Box 25542, London, ON N6C 6B2, CANADA. Canadian GST number: R-124213133RT001. Printed in the U.S.A .

www.spec t roscopyonl ine .com

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Columns

12

Classical Least Squares, Part XI: Comparison of Results from the

Two Laboratories Continued, and Then the Light Dawns

In the final installment of this series, the main problem is solved using the CLS algorithm to find

that the spectroscopy is sensitive to the volume fractions of the various components in a mixture.

Howard Mark and Jerome Workman, Jr.

18


Kicking off this new series on light-based technologies and applications, Spectroscopy

interviewed Andreas Velten about his work developing “femto photography” as a

postdoctoral associate at the Massachusetts Institute of Technology Media Lab.

Articles

Label-Free Chemical Detection in Microfabricated Devices 22 Using FT-IR Spectroscopic Imaging

A summary of some recent efforts to develop applications of Fourier transform infrared

(FT-IR) imaging for microfluidics and a discussion of different approaches (transmission and

attenuated total reflectance mode) to obtain FT-IR images of microfluidic devices.

K.L. Andrew Chan and Sergei G. Kazarian

Observing Heterogeneous Catalysts While They 32 Are Working Using Operando Raman Spectroscopy

The opportunities and current progress of operando Raman spectroscopy are presented

through examples based on the authors’ work.

M. Olga Guerrero-Pérez and M.A. Bañares

Energize Your Laboratory at the 2012 Eastern 40Analytical Symposium

The 2012 EAS program chair presents highlights of the invited symposia in spectroscopy and

related fields, from the perspective of what the chairs of the invited sessions had in mind

when developing the sessions and what you can expect to learn.

Mary Ellen McNally

October 2012

Volume 27 Number 10

��

Cover image courtesy of

iStockphoto/ThinkStock Images.

ON THE WEBFACSS-SCIX PODCAST SERIES

The final podcast in a series presented in

collaboration with the Federation of

Analytical Chemistry and Spectroscopy

Societies (FACSS), in connection with SciX

2012, the annual conference of FACSS:

Expanding the Frontiers of Raman

in Pharmaceutical Discovery and

Development

An interview with Don Pivonka, senior prin-

cipal chemist at Incyte Corporation and the

winner of the 2012 Charles Mann Award for

applied Raman spectroscopy.

spectroscopyonline.com/podcasts

FT-IR SPECTROSCOPY

In a new roundtable, experts discuss

the analytical capabilities for diverse

applications offered by Fourier transform

infrared (FT-IR) spectroscopy, as well as the

chemometric and spectral interpretation

software that are important elements of the

technique.

spectroscopyonline.com/TechForum

Join the Spectroscopy Group on LinkedIn

FUTURE OF LIGHT-BASED TECHNOLOGIES

CHEMOMETRICS IN SPECTROSCOPY

DEPARTMENTSNews Spectrum . . . . . . . 11 Product Resources . . . . .46 Showcase/Ad Index . . . .50

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Editorial Advisory Board

Ramon M. Barnes University of Massachusetts

Paul N. Bourassa Blue Moon Inc.

Deborah Bradshaw Consultant

Kenneth L. Busch Wyvern Associates

Ashok L. Cholli Polnox Corporation

David M. Coleman Wayne State University

Bruce Hudson Syracuse University

David Lankin University of Illinois at Chicago, College of Pharmacy

Barbara S. Larsen DuPont Central Research and Development

Ian R. Lewis Kaiser Optical Systems

Jeffrey Hirsch Thermo Fisher Scientific

Howard Mark Mark Electronics

R.D. McDowall McDowall Consulting

Gary McGeorge Bristol-Myers Squibb

Linda Baine McGown Rensselaer Polytechnic Institute

Robert G. Messerschmidt Rare Light, Inc.

Francis M. Mirabella Jr. Mirabella Practical Consulting Solutions, Inc.

John Monti Montgomery College

Michael L. Myrick University of South Carolina

John W. Olesik The Ohio State University

Jim Rydzak GlaxoSmithKline

Jerome Workman Jr. Unity Scientific

Contributing Editors:

Fran Adar Horiba Jobin Yvon

David W. Ball Cleveland State University

Kenneth L. Busch Wyvern Associates

Howard Mark Mark Electronics

Volker Thomsen Consultant

Jerome Workman Jr. Unity Scientific

Spectroscopy ’s Editorial Advisory Board is a group of distinguished individuals

assembled to help the publication fulfill its editorial mission to promote the effective

use of spectroscopic technology as a practical research and measurement tool.

With recognized expertise in a wide range of technique and application areas, board

members perform a range of functions, such as reviewing manuscripts, suggesting

authors and topics for coverage, and providing the editor with general direction and

feedback. We are indebted to these scientists for their contributions to the publication

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www.spec t roscopyonl ine .com October 2012 Spectroscopy 27(10) 11

Figure caption Figure caption Figure caption

News Spectrum

Demand for vibrational spectroscopy techniques in the oil and gas industry is quite strong and is seeing strong growth as a result of the development of biofuels. Although biofuels account for a small part of the oil and gas industry, they are one of the largest factors in driving the growth in demand for vibrational spectroscopy from the industry. The biofuels sector is a subset of the oil and gas industry, and consists of fuels derived from organic materials. The most common biofuels are bioethanol and biodiesel, and while they still account for only a small percentage of global fuel production, growth in this sector has been rapid. The same vibrational spectroscopy techniques popular for analyzing petroleum-based fuels are just as important, if not more so, for this burgeoning industry. Vibrational spectroscopy, which includes infrared, near-infrared (NIR), and Raman spectroscopy, is already widely used in both laboratory and process analysis applications in the oil and gas industry. Infrared spectroscopy, which consists mostly

of Fourier transform infrared (FT-IR) instruments, is by far the most popular, as it is capable of providing quantitation of key fuel components, especially in monitoring biofuel blends. Characteristics of NIR and Raman make them particularly useful in monitoring transesterification reactions, which are used to produce biodiesel fuels. The global market for laboratory

vibrational spectroscopy in the oil and gas industry was about $45 million in 2011, of which biofuel analysis accounts for only a small percentage. However, biofuels will unquestionably continue to be a major driver of demand for this class of instruments. The foregoing data were extracted from SDi’s market analysis and

perspectives report entitled The Global Assessment Report, 12th Edition: The

Laboratory Life Science and Analytical Instrument Industry, October 2012. For more information, contact Stuart Press, vice president, Strategic Directions International, Inc., 6242 Westchester Parkway, Suite 100, Los Angeles, CA 90045, (310) 641-4982, fax: (310) 641-8851, www.strategic-directions.com.

Market Profile: Vibrational Spectroscopy and Biofuels Analysis

A Model for R&D: The Center for Mid-Infrared Technologies for Health and the Environment

By Phillip Braun

The Center for Mid-Infrared Technologies for Health and the

Environment (MIRTHE) — an NSF engineering research center

headquartered at Princeton University — develops mid-infrared

(mid-IR) sources and sensor systems that aim to combine the

sensitivity and reliability of established, expensive spectroscopic

and spectrometric systems with the affordability and portability

of far less sensitive systems, enabling environmental, security,

and health applications. These include readily deployed point

sensors and sensor networks that provide extensive temporal

and spatial data for environmentally relevant trace gases;

inexpensive, widely accessible sensors for remote detection

of hazardous materials, and noninvasive, point-of-care disease

diagnostics and monitoring via breath and tissue analysis.

MIRTHE has employed ultrasensitive sensors for carbon

monoxide, carbon dioxide, nitrous oxide, nitric oxide, nitrogen

dioxide, ozone, ammonia, ethane, methane, isopropanol vapor,

and water vapor isotopes. Future targets include uranium

hexafluoride, formaldehyde, expanded hydrocarbon detection,

and additional compounds relevant to breath analysis. The

versatility of MIRTHE sensors for target gases is enabled by the

inherent usefulness of the mid-IR for sensing. In this spectral

range, many security, environmentally, and medically relevant

compounds have strong characteristic absorption features, from

which presence and concentration can be determined. Sensor

versatility is also enabled by the quantum cascade laser, which

is highly customizable and can be designed to emit at specific

wavelengths corresponding to absorption features throughout

the mid-IR.

MIRTHE takes a comprehensive, integrated approach to

sensor development. Its research relies on strong collaboration

with industry and talented students of Princeton University as

well as the organization’s academic partners — Johns Hopkins

University, Rice University, Texas A&A University, University of

Maryland Baltimore County, and the City College of New York,

and clinical partner St. Luke’s Hospital. As students assist world-

class faculty in sensor research, and through participation in a

core education program, they become highly trained and skilled

in all aspects of mid-IR sensing, from fundamental materials

development to field implementation and data analysis.

Industry affiliates participate closely in the education and sensor

development processes, giving them access to excellent talent

and speeding commercialization.

MIRTHE further expedites the commercialization process

with its Investment Focus Group, which brings the investment

community together with engineers, clinicians, federal

funding agencies, and industry affiliates to formulate

strategies for translating MIRTHE technology from R&D to

commercial production.

MIRTHE is constantly seeking new collaboration partners as

well as novel applications for its affordable, compact, highly

sensitive mid-IR sensors, in addition to those application foci

and structures already in place. For more information or to

become a MIRTHE member, visit www.mirthecenter.org. ◾

Infrared - 64%

Near-Infrared - 27%

Raman - 9%

64%27%

9%

Vibrational spectroscopy demand from oil and gas applications in 2011.


Chemometrics in Spectroscopy

Howard Mark and Jerome Workman, Jr.

Finding that the experiments performed in two different laboratories gave substantially the same results, we redoubled our efforts to determine the cause of the discrepancy between the spectral and reference concentrations. Serendipity leads to success.

Classical Least Squares, Part XI: Comparison of Results from the Two Laboratories Continued, and Then the Light Dawns

This column is the last installment of our discussion of the classical least squares (CLS) approach to calibration (1–10). Our previous column (10) discussed how we ob-

tained results from the second laboratory that had essentially the same properties as the results from the first laboratory, de-spite the fact that it was a different laboratory, the experiments were performed by different scientists, and the mixtures used contained different materials. In both cases we examined the results for possible experimental blunders, and for both labo-ratories we rejected the hypothesis that experimental problems were the cause of the unexpected results.

This being the case, we are forced to the conclusion that there is some real, previously unsuspected, physical phenom-enon affecting the behavior of the samples or the spectroscopic measurement. At this point, we have no clue as to the nature of the phenomenon. The only course of action left to us is to continue the analysis of the data as we had done previously, keeping an eye out for any other unexpected effects that might relate to an explanation of the results. The next step in the analysis of the first set of experimental measurements was to compute the mole percent values of the various mixture components, and compare those values with the CLS values

computed from the spectral data. Therefore, we computed the mole percents for the samples from the second laboratory, and compared them with the spectral results. Table I presents that set of comparisons.

We can see that the agreement between the CLS-deter-mined percents and the mole percents is about the same as what we found in the comparison with weight percents, with errors for some samples being as much as 10–15%.

Furthermore, from Table IV in part X of this series (10) (for weight percents from the second laboratory) as well as from Table V in part VIII (8) (for mole percents from the first laboratory), we find that the nature and the approximate mag-nitudes of the discrepancies are roughly the same for all three sets of comparisons.

This finding was both encouraging and discouraging. It was encouraging because it demonstrated whatever the effects that are operative, they are reproducible, and this provides further confirmation that they represent real physical phenomena, even though we didn’t know which phenomena those were. On the flip side of the coin, it was discouraging for the same rea-son: It provided no further insight into the nature of the cause (or causes) of the errors.


At this point, there seemed to be no further direction to go in other than to continue the analysis of the data the same way we did according to the previ-ous schema: to compute the percentage of hydrogen atoms from each compo-

nent of the mixtures, and then compute the percentage of hydrogen atoms after correcting for the density of the various components. It was all a bit depressing, since there was no real expectation that we would find some new or different

results that would point us in the proper direction.

The Light DawnsThen serendipity struck.

Figure 1 in part V (5) specified the ex-

Table I: Comparisons of spectroscopic values with mole percents for data from the second laboratory

Sample Mole Percent CLS Percent

Toluene Chloroform Heptane Toluene Chloroform Heptane

1 100 0 0 100 0 0

2 69.22 30.77 0 73.43 22.46 0.11

3 80.53 0 19.46 76.33 0.84 22.95

4 42.84 57.15 0 48.48 47.62 -0.7

5 49.27 32.86 17.86 49.35 24.4 23.57

6 57.96 0 42.03 51.52 1.2 47.49

7 19.99 80 0 23.02 72.78 0.04

8 22.76 60.72 16.5 24.36 49.76 23.87

9 26.42 35.24 38.32 25.22 25.36 48.5

10 31.49 0 68.5 25.96 0.26 73.27

11 0 100 0 0 100 0

12 0 84.65 15.34 0.74 75.83 23.79

13 0 64.78 35.21 0.56 51.55 48.83

14 0 38.01 61.99 0.42 25.86 74.35

15 0 0 100 0 0 100


perimental design, and from that we know that all concentra-tions have a target value (in their appropriate units) that is one of the values from the set (0, 25, 50, 75, and 100). One day while trying to tear out only the white hairs (so as to at least leave the dark ones in place), attention was drawn to the CLS values in Table I. We extracted those values and present them in Table II by themselves.

The realization suddenly struck that the values in Table I are all within a couple of percent points of one of the values from the set making up the experimental design. We recalled that for the second laboratory the experimental design was implemented by apportioning out the specified volume of the specified component. This allowed the immediate creation of the hypothesis that the physical phenomenon involved in the absorption of light is the volume percent of the corresponding component, not the weight percent, which is the concentration unit most commonly used in chemical analysis.

The first test of this hypothesis, of course, was to compare the various CLS values computed with the target values specified by the experimental design. We show this comparison in Table III.

From Table III it appears eminently clear that indeed, not only are the individual readings within the range of values used in the experimental design, but each one also corresponds to the actual value specified by the experimental design, within a moderate experimental error. This leads us to the tentative hypothesis that the concentrations determined by CLS analysis of absorbance data correspond to the volume percents of the components in the mixture corresponding to the various sam-ples. That is, the spectroscopy is sensitive to the volume per-cents of the components in a mixture. A hypothesis like this is, of course, what we have been searching for. Having found a tenable hypothesis, it raised a number of questions:1: Why didn’t we observe this correspondence in the data

from the first laboratory?2: Is volume percent a more reasonable unit for spectroscopic

analysis than the other units that are commonly used?3: When mixing different materials, it is common that there

Table II: CLS values from the second laboratory

Sample Toluene Chloroform Heptane

1 100 0 0

2 73.43 22.46 0.11

3 76.33 0.84 22.95

4 48.48 47.62 -0.7

5 49.35 24.4 23.57

6 51.52 1.2 47.49

7 23.02 72.78 0.04

8 24.36 49.76 23.87

9 25.22 25.36 48.5

10 25.96 0.26 73.27

11 0 100 0

12 0.74 75.83 23.79

13 0.56 51.55 48.83

14 0.42 25.86 74.35

15 0 0 100

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is shrinkage of the total volume, compared to the sum of the volumes of the components; this is commonly called the partial molal volume. How do we know that our sam-ples are not affected by this phenomenon, and if so, can we gain any insight about it or from it?

4: How can we confirm this hypothesis?The answers that emerged are as follows.

Response to Question 1: We didn’t observe a correspondence between the CLS values from the first laboratory and the ex-perimental design because the experimental design was imple-mented in samples that were made gravimetrically. From Table I in part X (10) we see that there are large disparities between the weight percents and volume percents for the constituents in most of the samples. Thus, a sample specified as having a par-ticular composition according to weight would not necessarily have the same, or even nearly the same, value for composition when expressed as volume. Therefore, if the hypothesis is cor-rect, then the values obtained from the spectra through the use of the CLS algorithm would follow the volume percents, which are likely not to match the weight percents, and thus we do not observe a correspondence to the experimental design.

Response to Question 2: On reflection, there would seem to not be any reason for a connection between spectral behavior and weight percents of the components in a sample. Nor is there any physical reason to expect the component weight to play a role in the spectral behavior because the weight of a molecule does not affect the molecular behavior; on the contrary, the weight is a result, not a cause, of the underlying molecular structure and be-havior. On the other hand, it is not clear a priori whether volume percents are “more reasonable” than weight percents. As we will show in a future column, however, it is possible to mathemati-cally derive the fact that by starting with Beer’s law, spectra of mixtures can be shown to exhibit absorbance directly related to the volume percents of the components of the mixture.

Response to Question 3: The derivation described in the answer to question 2 describes what happens when Beer’s law holds rigorously, which includes the fact that the absorbances add in strict proportion to their concentrations, and also in proportion to the absorbance of the pure materials. This is equivalent to an assumption that no partial molal effects are operative. It is not yet clear what we should expect to happen if one, or the other, or both of these conditions do not occur. In a future column, we will discuss this situation further. For now we will simply note that in a previous column (1), where the components are known to interact and mixtures are known to exhibit shrinkage, the spectrum of the mixture was severely distorted by the interaction, so that the mixture spectrum could not be regenerated from the spectra of the components.

Response to Question 4: The answer to our puzzle was found partially through serendipity. The answer to question 4 can also be found in another aspect of the serendipity that underlay the experiment. Question 1, and the answer to it, brought out the fact that we couldn’t find a correspondence between the

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spectroscopic values and the weight per-cent values, because the spectroscopic values were not sensitive to the weight percents.

It follows, therefore, that if we com-pute the corresponding volume percent-ages for the components used by the first laboratory, this will provide evidence as to whether or not the hypothesis we formed to explain the results is correct. In fact, this is a direct example of what is called the scientific method in action: Based on the result of one experiment (in this case the data from the second

laboratory) we were able to form a hy-pothesis (that volume percents were the operative characteristic in explaining the absorbance of the spectra of mixtures). The serendipity involved here is the fact that we already had the data we needed to verify whether our hypothesis is cor-rect, and all we need to do is carry out the necessary calculations.

The next step in applying the scientific method to the problem at hand is to see if the hypothesis formulated can predict the results of a different experiment. Therefore, now we apply this hypothesis

to predict the results of a different experi-ment (in this case, the results from the first laboratory). We previously com-pared the CLS values from the first labo-ratory only to the weight percent, mole percent, and values for the concentration in some other units (for example, see Table III in part VIII [8] for the compari-son of CLS values to weight percents). Now, we will compare the CLS results from the data from the first laboratory to the volume percents of the components in those mixtures. If the CLS results agree with the volume percents of the mixture components in that set of sam-ples, then this constitutes strong evidence that the hypothesis is correct.

Table I in part X (10) presented the correspondences between volume percents and weight percents for the samples from the second laboratory, and from this table we were able to compare results in both of those units to the spectral results. Similarly, in Table IV we show the correspondences between weight percents and volume percents for the samples from the first laboratory.

We note in Table IV the same phe-nomenon we observed previously in Table I in part X (10): the conversion of concentration values between differ-ent units is not unique. We note that toluene, for example, has roughly a 2% difference between two samples when expressed as weight percent (76.4% and 74.1%), but an almost 15% difference

Table IV: Conversion from volume percents to weight percents for samples from the first laboratory (Buchi)

Weight Percent Values Volume Percent Values

TolueneDichloro- methane

n-Heptane TolueneDichloro- methane

n-Heptane

100 0 0 100 0 0

76.40 23.60 0 83.30 16.69 0

74.10 0 25.90 69.29 0 30.70

50.30 49.70 0 60.93 39.06 0

48.90 025.11 25.99 49.82 16.60 33.79

49.94 0 50.06 44.03 0 55.96

25.30 074.77 0 34.27 65.72 0

25.33 49.65 25.02 28.37 36.08 35.53

23.86 26.45 49.68 22.93 16.50 60.56

25.19 0 74.81 20.98 0 79.01

0 100 0 0 100 0

0 75.04 24.96 0 60.60 39.39

0 49.54 50.46 0 33.44 66.55

0 24.34 75.66 0 14.13 85.86

0 0 100 0 0 100

Table III: Comparisons of spectroscopic values from the second laboratory with experimental design target values

Sample Design Targets CLS Percent

Toluene Chloroform Heptane Toluene Chloroform Heptane

1 100 0 0 100 0 0

2 75 25 0 73.43 22.46 0.11

3 75 0 25 76.33 0.84 22.95

4 50 50 0 48.48 47.62 -0.7

5 50 25 25 49.35 24.4 23.57

6 50 0 50 51.52 1.2 47.49

7 25 75 0 23.02 72.78 0.04

8 25 50 25 24.36 49.76 23.87

9 25 25 50 25.22 25.36 48.5

10 25 0 75 25.96 0.26 73.27

11 0 100 0 0 100 0

12 0 75 25 0.74 75.83 23.79

13 0 50 50 0.56 51.55 48.83

14 0 25 75 0.42 25.86 74.35

15 0 0 100 0 0 100


(83.3% and 69.2%) when expressed as volume percent. The other constituents behave similarly. Again, we will defer further discussion of this point until a suitable time later.

For now, we return to our main dis-cussion and point out that above, we ex-plained why we saw no correspondence between the weight percent values and the spectral values in the data from the first laboratory, and Table IV gives us the information we need to make the com-parison with the volume percent values. All we need to do now is to take those values of volume percent from Table IV and use them in place of the weight percents from Table III in part XIII (8). Table V shows those results.

A cursory examination of the cor-responding values in Table IV reveals excellent agreement between the volu-metric percentages and the CLS calcu-lations for the concentrations.

Thus, this application of the scientific method, albeit in a microcosm, has suc-ceeded in verifying the hypothesis we formulated: The operational variable in optical spectroscopy is the volume per-centage of the components. Therefore, we conclude that the volume percentages of the components is the physical char-acteristic of materials that the measure-ment of absorbance is in fact sensitive to.

We have solved our main problem, in using the CLS algorithm to find that the spectroscopy is sensitive to the volume

fractions of the various components in a mixture. Although many questions are still left open, and this result has important implications and ramifica-tions, including explaining the behavior of the more conventional calibration algorithms, some of these are briefly de-scribed in a 2010 publication (11) and the interested reader may want to inspect that. However, “Chemometrics in Spec-troscopy” is about more than this one finding, important as it is. Therefore, we will interrupt this discussion in favor of other topics related to chemometrics in spectroscopy, in some cases stepping back for a less detailed but more encom-passing perspective, or “a view from a height,” to quote Isaac Asimov.

References

(1) H. Mark and J. Workman, Spectroscopy

25(5), 16–21 (2010).


25(6), 20–25 (2010).


25(10), 22–31 (2010).


26(2), 26–33 (2011).


26(5), 12–22 (2011).


26(6), 22–28 (2011).


26(10), 24–31 (2011).


27(2), 22–34 (2012).


27(5), 14–19 (2012).


27(6), 28–35 (2012).

(11) H. Mark, R. Rubinovitz, D. Heaps, P. Gem-

perline, D. Dahm, and K. Dahm, Appl.

Spect. 64(9), 995–1006 (2010).

Howard Mark

serves on the Edito-rial Advisory Board of Spectroscopy and runs a consulting service, Mark Electronics (Suffern, New York). He can be reached via

e-mail: [email protected]

Jerome Work-

man, Jr. serves on the Editorial Advisory Board of Spectros-copy and is the Ex-ecutive Vice President of Engineering at Unity Scientific, LLC,

(Brookfield, Connecticut). He is also an adjunct professor at U.S. National University (La Jolla, California), and Liberty University (Lynchburg, Vir-ginia). His email address is [email protected]

For more information on this topic, please visit:

www.spectroscopyonline.com

Table V: Volumetric percents and spectrally calculated compositions using the CLS algorithm for all samples from the first laboratory

Sample Volume Percent Values Spectroscopic Values

Toluene Dichloromethane n-Heptane Toluene Dichloromethane n-Heptane

1 100 0 0 100 -0.00 0.00

2 83.30 16.69 0 83.06 14.39 1.58

3 69.29 0 30.70 70.45 0.72 29.21

4 60.93 39.06 0 61.04 35.35 3.03

5 49.82 16.60 33.79 50.76 15.84 33.79

6 44.03 0 55.96 45.57 0.76 54.33

7 34.27 65.72 0 34.78 62.43 2.68

8 28.37 36.08 35.53 28.82 35.17 36.53

9 22.93 16.50 60.56 23.67 15.54 61.30

10 20.98 0 79.01 21.98 0.47 77.85

11 0 100 0 -0.00 100 0.00

12 0 60.60 39.39 -0.47 61.19 40.87

13 0 33.44 66.55 0.50 34.76 67.21

14 0 14.13 85.86 0.33 14.72 86.47

15 0 0 100 0.00 -0.00 100


THE FUTURE OF LIGHT-BASED TECHNOLOGIES

CHAD BAKER/GETTY IMAGES

Xxxx_xxxxx_xxxx www.spectroscopyonline.com

Today, the capabilities of modern technologies are constantly increas-ing, and instruments are becoming

smaller, faster, cheaper, more portable, and more easily interconnected. This is true for many analytical spectroscopy techniques as well as for a wide range of other tech-nologies that have the potential to intersect with the field of spectroscopy and expand its boundaries. To explore these develop-ments, Spectroscopy is launching an ar-ticle series about new technologies and new applications of existing technologies that are based on or related to light. We kick off the series with this interview with Andreas Velten about his work as a post-doctoral associate at the Massachusetts Institute of Technology (MIT) Media Lab in Cambridge, Massachusetts. (Velten has since taken a position as associate scientist at the Morgridge Institute for Research at the University of Wisconsin in Madison).

Velten and his colleagues in Professor Ramesh Raskar’s “Camera Culture” group at the MIT Media Lab, in collaboration with the spectroscopy laboratory of MIT Professor Moungi Bawendi, developed a technique they called “femto photography.” The technique uses a titanium–sapphire laser that emits pulses every ~13 ns, pico-second-accurate detectors, and complex mathematical reconstruction techniques. By combining hundreds of “streak” im-ages (one-dimensional movies of a line),

captured with this high-speed camera, they have created moving pictures (never perhaps was there a more apt use of the term) that show the movement of light (groups of photons). Examples of their use of the technique include combined images of light traveling through a soda bottle and, in a separate application, over a piece of fruit.

Spectroscopy: How did the femto photog-

raphy project get started?

Velten: About two years ago, I joined Ra-mesh Raskar’s group at the MIT Media Lab to do a post-doc. Ramesh had been thinking for a long time about combining ultrafast optics and computational pho-tography to build an imaging system that can look around corners. He and his group had taken some initial steps in implement-ing the idea. It’s kind of an unusual match, because my background is in ultrafast op-tics and this group is doing computer vi-sion and computational photography. But it’s very interesting to combine the two fields. People in ultrafast optics are trying to push the envelope of the hardware — to see how short we can make the pulses, to improve ranging. For example, with light detection and ranging (LIDAR) we send a laser pulse to a target and wait until the light comes back, and from the time that has passed, we can measure the distance to the target. It’s used in traffic control these days. But I was thinking about imaging and what could be done with imaging data in signal processing.

On the other hand, with computa-tional photography people basically take consumer cameras and make small modifications to them, and do amazing

things by processing the data and look-ing at the data in a new way. Our project is kind of a combination of the two fields. We use nonstandard hardware — hard-ware you can set to the time of flight of the light that you are using it for imaging. We wanted to develop new capabilities of this method by further processing the data. The initial goal was to build a cam-era that could image around a corner (a special application).

Spectroscopy: So how did you end up

photographing visible light photons —

in other words, doing photography at

the speed of light?

Velten: Once you have the time-of-flight imaging, you can get a lot more informa-tion from the light by post-processing the data. Professor Raskar and our whole Camera Culture group is very interested in computational photography and were inspired by the “bullet through an apple” strobe photos by Doc Edgerton. I had taken some of our streak camera images and created one-dimensional movies. Pro-fessor Raskar challenged us to think about ways to convert the one-dimensional streak tube to create visually meaningful ultrafast two-dimensional movies. I real-ized at some point, from playing with the camera, that you could actually compose movies — that you could stitch the data together in a way that would allow you to reconstruct a complete movie out of the data that you capture. Making these movies was really a side project. Our team, especially Everett Lawson and I, started to put together a mirror based system. Then a set of collaborators, Diego Gutierez, Di Wu, and members of Diegos group,

More Online:


To see the moving images produced at the MIT Media Laboratory, and more about their work, visit: http://web.media.mit.edu/~raskar//trillionfpshttp://www.mit.edu/~velten/press/content/http://www.mit.edu/~veltenhttp://cameraculture.media.mit.edu/


Adrian Jarabo, Elisa Amoros Galindo, and Belen Masia, got excited and worked on visualizing the results better in the videos and doing things like generating single pictures from them.

Spectroscopy: How do you create such

clear moving images from multiple still

images?

Velten: We use a titanium–sapphire laser that gives very regular pulses, and the camera is synchronized to that. The cam-era takes lots of images of the scene, but because the camera and the laser are very well synchronized and everything is very regular, the images all look the same. So we can just stitch them together to get the final moving image of the scene.

Spectroscopy: Does it take a lot of time or

work to put them together?

Velten: The image capturing is what takes hours, actually. To get a movie that looks really good, you need quite a

few shots. And it takes much longer to set everything up.

Then there’s the post-processing. What you see is actually a color photo in the background, and the light is put on top of that. The raw, straight camera images are all black and white; the color is added for visualization. That’s all post-processing. If you watch the videos, the plain data — the pulsed elimination only, which shows how the plain black-and-white image from the laser looks — is always there in the videos.

Spectroscopy: The photons moving

through the soda bottle look like a fluid

in motion; there is more velocity at the

center than at the outside, and then it

seems to bunch up at the spout. What

do you think is going on?

Velten: The view of what you see is a little distorted, because you don’t see an event when it’s actually happening; rather, you see it when the light from the event has traveled to the camera. I think that’s why

it looks like things are moving slower far away from the pulse than close to the pulse, because there is a distortion that comes from the light having to travel to the camera.

Spectroscopy: What potential ap-

plications do you see for using this

technology?

Velten: One idea is to use this technology to look into materials, because some of the light always travels into the material and some scatters back out. You can see this very nicely in our images of the tomato: The tomato actually keeps glowing after it has been exposed, because light travels in-side and then slowly comes back out. From that light, you could actually get informa-tion about what is going on inside that material, if you developed a proper way of probing and analyzing the materials that you are looking at. There is currently some interest in this. Many people have tried to image living tissue, for medical applications, like doing an ultrasound or

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X-ray with light, which potentially has a lot of advantages over the common X-ray, because it would be practically harmless. That is one thing people are trying.

For industrial imaging, you could try to detect cracks inside material, if some light is actually transmitted through. You don’t need a lot, you just need a little bit of light coming through and coming back out. By analyzing how the light scatters off the materials, we can learn a lot about the material.

Spectroscopy: For potential applications like medical imaging, to what level of detail or size can you see things?

Velten: That’s an open research question, because really, you are posed with a data collection and processing problem. The information that the light gets — the wavelengths, the resolution of the light — is very high, so you should be able to get quite detailed information out. But the scattering inside the material destroys a lot of that information by bouncing the light around. And then the question is, How well can you detect the intensity of what is coming out (not only the time it takes for the light to come back out) and how well can you computationally reconstruct what is inside the material? It depends a lot on how deep the material is, obviously.

Spectroscopy: Can you envision using different wavelengths so that you could actually make vibrational spectroscopy measurements?

Velten: Our limitation right now is that we only have one light source at 800 nm. So the movie, the moving part of it, is ac-tually in the near infrared. But if we had three different light sources, red, green, and blue, or a tunable light source, like if you used an optical parametric oscil-lator (OPO) instead of a titanium–sap-phire laser, then we could scan different wavelengths or even try to send a broad spectrum in and learn more about the spectral properties of the material. That is something we are looking into.

The vibrational modes in some materi-als are slow enough that you could actually see something happening. You wouldn’t just see a spectral signature; I think you

might be able to see the vibration happen-ing inside, the frequency. That would be very interesting.

For this camera, or at this point for this camera, it would need to be something macroscopic — something we could put in front of the camera and in which we could excite enough molecules or enough material simultaneously so we could actu-ally see something.

Spectroscopy: What do you envision this high-speed camera technology may be able to do in terms of measuring and studying the interaction of light with various media, such as liquids, powders, and large and small particles?

Velten: We have done some of that. It’s al-ways an interesting game to put something in front of the camera to see if the camera can detect something interesting, because the amount of information you get in one of these exposures is actually quite big, and you may, by chance, discover some-thing that has been missed before. Visu-ally analyzing something is an incredibly powerful technique, compared to looking at things with a computer or looking at plots, or just numbers.

Applying this technology to spec-troscopy techniques is a very interest-ing direction to take this work. There are, of course, a lot of interesting effects that occur when you hit something with a very powerful laser pulse and evaporate material. Of course, usu-ally that is a very small effect, and you would need a microscope in front of our camera to see something there. But all these things are interesting. You could trace plasmas in the air; light filaments would also be interesting to look at. At this stage, we are just brainstorming about all the things that could be done by looking at things with this speed.

Right now our limitation is that we need repeatable events. We have to be able to re-peat the same thing over and over again many times to collect enough data to cap-ture the movie. That limits some of the applications that you can actually do in terms of looking at interactions with mat-ter, because often you destroy your sample the first time you shoot light at it, and then you’re done.

Spectroscopy: There has been so much work done using simulations to gener-ate models for how light interacts with multiple particles of different sizes, de-pending on their scattering properties or absorptive properties. Is that a potential field of use?

Velten: We have done a little bit of that sort of thing, such as taking tissue samples or materials like wax, and trying to analyze them. So far we have been looking more in the direction of computer graphics, which is more about how things look than what’s actually happening. That’s the background of the group, and that’s why we have done some work in that direction. But the other direction, of looking at scattering models, is also very interesting and a worthwhile direction for this research.

Spectroscopy: This work brings to mind the dramatic effects of high-speed cam-eras, such as in “The Matrix,” when you see a bullet moving very slowly and inter-acting with the images of the people and the scene around it. At the high speed of your cameras, you could actually do the same thing with light moving through a scene, right?

Velten: It’s very interesting. Actually, if you were to capture a bullet with this camera, that is, if you could shoot the bullet several times and actually make a movie of the bullet, it would take about three years to watch the film of the bullet going from one side of the scene to the other. That’s true for almost any piece of matter. So I don’t think you will ever look at solid or atomic matter with this camera, unless you have a very violent explosion, because there is just not enough happening in a time frame that is interesting to watch.

The other question people ask is, Don’t you capture a lot of data? Well, we capture 512 frames, so it’s not a lot, about half a megabyte per frame. If you were actually capturing a whole second, of course there would be a lot of data, but it would also take tens of thousands of years to watch. So there is no point in capturing a full sec-ond’s worth of data.

Spectroscopy: What are your next steps with this work?


Velten: We have a publication that is under review right now, using an application of this time-of-flight imaging. We have an-other one we just submitted that is about further processing and visualizing the data — visualizing the movies, essentially.

Beyond that, many other things that have been done in computer vision and computational photography can also be done using this system and using this camera. We would like to go through those and demonstrate them one by one, to demonstrate the capabilities, including some things that were not possible before, like looking inside materials from a dis-tance by analyzing the scattering and the time of flight. We also have received some interest from people who would like to in-vestigate scientific phenomena, to lead to new discoveries. So that’s an interesting direction that will also be explored.

The other thing that comes to mind is improving the system. Right now, it uses a lot of high-end equipment that is bulky and heavy. It’s really a laboratory setup. For many applications, it would be bet-

ter to make it much more compact and much more portable. So we are working on building a dedicated compact system.

Spectroscopy: What plans do you have to

partner with other scientists at MIT or

other universities?

Velten: We don’t have any thing concrete yet. We have chatted with a number of people who are interested, but we are still exploring what kind of concrete collabora-tions could come out of it.

Here at MIT, for example, Professor Moungi Bawendi (of the spectroscopy laboratory) is providing the equipment for us, and is also a member of this proj-ect. He usually works on spectroscopy and quantum dots, so he is an interesting part-ner for the spectroscopy and nanocrystal applications.

We are also interested in working with the people at the MIT Edgerton Center, be-cause we see our work as being kind of in line with the work that Doc Edgerton did about 50 years ago. I don’t know if you’ve

ever seen those art photography pictures of a bullet going through an apple. That was done at MIT. I think it was kind of a similar situation, that he had this equip-ment, and wondered if he could just take still pictures with it, and he came up with that stunning photography. That is still on display in the Edgerton Center, and I think it’s mentioned on our web page.

Another person is Nils Abramson in Sweden who did light-in-flight holography back in the 1970s, also trying to capture light moving, with holographic film. He had some very interesting short movies of moving light and things like that. He is retired, but we are in contact with him.

Most of these things are in the early stages of just talking to people and seeing what can be done. ◾

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Microfluidic technology is a powerful tool that has a wide range of applications in chemical and biological analysis (1). The improved heat and mass transfer in

microfabricated systems in comparison to traditional processes provides the opportunity to increase control over the yield, the speed of the turnover of experiments for high-throughput studies, and reduce the amount of precious reagents used (2). Knowing the chemical composition at a specific point in the microfabricated device can aid in the design and optimization of these devices (3,4).

Detection in microfabricated devices often relies on addi-tional tracers or tags to visualize the existence and the dis-tribution of particular components. One of the most widely used methods is confocal fluorescence microscopy. The ad-vantage of fluorescence is that it is highly sensitive (5) and can often achieve sufficient spatial resolution. However, finding a suitable fluorescence agent and photobleaching are some of the remaining challenges to overcome. The tracer also has to be inert enough that it will not decompose or interfere with the process of interest (for example, chemical reactions and diffusion). Raman, surface-enhanced Raman spectroscopy (SERS), and coherent anti-Stokes Raman scattering (CARS) have been shown as promising label-free detection methods in microfluidic systems (6–10). In this article, we discuss some recent studies that have demonstrated that Fourier transform infrared (FT-IR) spectroscopic imaging can be a powerful de-tection tool, as was proposed earlier (11), to extract spatially

resolved rich chemical information from microfluidic devices in a label-free manner.

FT-IR Spectroscopic ImagingFT-IR imaging has been used as a highly versatile analytical method, providing spatially resolved, chemically specific in-formation for studying multicomponent systems (12). Recently, conventional FT-IR microscopy using a single-element detec-tor was applied to analyze fast reactions in microfluidic flows where spectral information from a specific location in a channel was obtained (13). FT-IR spectroscopic imaging combines the benefits of imaging and spectroscopy providing chemical maps of studied samples. The chemical specificity comes from the intrinsic molecular vibrations, revealed by spectral bands, while spatial information is collected from the focal plane array (FPA) detectors. An FPA detector comprises thousands of detector pixels, each collecting an infrared spectrum so that thousands of infrared spectra are collected simultaneously in a single im-aging measurement. This approach reduces the time required to collect all the spectral data when compared to point-to-point mapping using a single element detector with apertures (14).

Characteristic spectral bands can then be used as markers for specific components, which allows their distribution within the imaged area to be revealed. Multivariate methods are also available to separate components with similar spectral fea-tures to generate representative maps for each component. A full mid-IR spectrum (4000–900 cm-1) is collected from each

K.L. Andrew Chan and Sergei G. Kazarian

Fourier transform infrared (FT-IR) spectroscopic imaging is a highly versatile technique that can be applied to a wide range of systems. This article summarizes some of the recent efforts developing applications of FT-IR imaging for microfluidics. The main advantage of FT-IR imaging compared to traditional imaging methods is that it is a label-free imaging technique. There is no need to develop tags or labels, multiple components are simultaneously traced, and images can be taken without disturbing the sample. All of these advantages are accompanied with a near-video frame rate acquisi-tion speed. Different approaches to obtain FT-IR images (transmission and attenuated total reflection mode) of microfluidic devices are discussed including novel ways to create microfluidic devices.

Label-Free Chemical Detection in Microfabricated Devices Using FT-IR Spectroscopic Imaging

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for GC/LC/SIMS

for TOF-MS


detector pixel, and multiple components can be simultaneously tracked in one single imaging measurement either using univariate or multivariate approaches. This multicomponent imaging feature is a significant advantage compared to ordinary fluorescence measurements in which only one component is traced at a time. The absorbance of a spectral band is directly correlated to the concentration of the component so that results obtained can be quantified.

Because all spectra are collected si-multaneously, FT-IR imaging using FPA detectors is suitable for studying dynamic systems such as diffusion and dissolution (15–20) and has great potential for high-throughput applications, especially when combined with the attenuated total re-flection (ATR) sampling method (11,21).

ATR Imaging In the ATR approach, the infrared light is totally internally reflected at the inter-face between the high refractive index infrared-transparent element and the lower refractive index medium (the sample). Common elements used for ATR measurement are diamond (n ≈

2.4), ZnSe (n ≈ 2.4), Si (n ≈ 3.4), or Ge (n ≈ 4). In this measurement mode, the infrared light probes into the sample as an evanescence wave, the field strength of which decays exponentially into the sample. The depth of penetration is on the order of a few micrometers and the resultant pathlength (the equivalent pathlength) is also in the order of several micrometers depending on the refractive indices of the sample, the ATR element, and the incident angle. The ATR element is selected such that it will provide a rela-tively small, but known, pathlength that will produce an appropriate on-scale ab-sorbance. Other considerations include the physical and chemical properties of the ATR element for specific applica-tions. The generally small pathlength from ATR mode measurement offers the opportunity to measure materials that have strong mid-IR bands such as water and reduces sample preparation because no microtoming or polishing of the sample is required. The possibility of acquiring spectra using ATR mode in-creases the applicability to study samples in situ and to monitor processes on line. The simplicity of measurement allows

rapid analysis of an array of deposited samples in the imaging area (11,21–23).

Combined FT-IR Imaging and Microfluidics ATR Mode

Because the evanescent wave probes a rel-atively shallow layer, the sample must be in close contact with the ATR element to be exposed to and interact with this eva-nescent wave. This sampling requirement for ATR measurement is automatically satisfied when the sample being mea-sured is a fluid. FT-IR imaging in ATR mode is therefore suitable to study mi-crofluidic systems. Microfluidic devices are often made of polydimethylsiloxane (PDMS) using templates in which chan-nels are created when the PDMS stamp is bonded to a flat surface such as glass. With ATR FT-IR imaging, instead of bonding the PDMS device to glass, the PDMS device is bonded to the imaging surface of the ATR element so that the measuring surface forms one of the walls of the microfluidic channel. The fluid flowing inside the channel that comes to close proximity with the surface of the ATR element is measured.

ATR elements are often expensive and cannot be used as disposable units; therefore, the bonding of PDMS onto the ATR surface must be reversible. PDMS will bond weakly with a clean, oil-free surface. However, most micro-fluidic experiments cannot rely on this weak bonding as the seal for the chan-nels because pressure from the fluid will cause liquid to escape by overcoming this weak adhesion force. Fortunately, this issue can be easily rectified. A rigid poly(methyl methacrylate) (PMMA) sheet (or any rigid, ideally transparent material for visible inspection) can be used as a press to provide a stronger bonding between the PDMS and the ATR element. One of the inherent ad-vantages of ATR imaging measurements is that the presence of foreign particles (dust) that may affect contact quality between the PDMS chip and the ATR surface can be easily detected (24). Leak-age of f luids through the gap between the ATR surface and the PDMS chip can also be detected from the image as the escaped fluid will be in contact with the ATR element. Figure 1 shows the typi-

1 mm

Figure 1: Top left: The “Y-junction” PDMS microfluidic device. Middle: The PDMS microfluidic

device on the ATR imaging surface. Imaging area is indicated by the red rectangle. Bottom right:

RGB imaging of a Y-junction microfluidic device with water entering from the right and PEG 200

entering from the left measured with macro ATR FT-IR imaging. Red, blue, and green represent the

presence of PDMS, water, and PEG 200, respectively. The imaging area is 2.56 mm × 3.58 mm.


cal “Y-junction” PDMS microfluidic device that we have used as the first test of the principle (25). An image of the device can be generated based on the band specific to PDMS. When two different fluids are injected from the two entrances of the microfluidic device, the mixing between the two fluids can be studied. As an illustration, we injected water (75 µL/h) through the right entrance and PEG 200 (25 µL/h) through the left channel. Because both fluids are transparent in visible range, it was not possible to visualize the flow pattern using visible light without adding dye to the solution. Using ATR FT-IR imaging, the two fluids are easily distinguished. Water can be traced using the ν(O-H) band at 3700–3100 cm-1, and PEG 200 can be traced using the characteristic ν(C-H) bands at 3000–2800 cm-1. A red-green-blue (RGB) figure (Figure 1) has been created to show the distribution of PDMS (red), water (blue), and PEG (green). The image allows us to immediately identify the effect of viscosity to the flow pattern. The water stream, despite having a higher flow rate, was constrained to the right while most of the channel was occupied by the PEG 200 because of the difference between their viscosities.

Transmission Mode

There are both advantages and disadvantages to working in transmission mode. One of the main advantages is that the whole volume of the fluid is analyzed as compared to the first few micrometers from the surface in ATR mode. However, for the same reason, one of the main disadvantages is that the fluid

thickness is often limited to ~10 µm to ensure that most of the spectral bands are within the linear detection limit (around 0.8 absorbance units). For the stronger spectral bands such as the band from water ν(O-H) mode, the thickness may need to be further reduced to 2–3 µm. In general, therefore, certain parts of the spectral region will not be accessible in transmis-sion with a workable pathlength when the fluid studied has strong spectral bands.

1 mm

Figure 2: A picture of the wax-printed microfluidic device before being

sandwiched between the two CaF2 windows for imaging in transmission.

Rigaku Corporation and its Global Subsidiarieswebsite: www.Rigaku.com | email: [email protected]


To study in transmission mode, the top and bottom layer of the microflu-idic device has to be transparent in the infrared region. Common infrared-transparent materials used for making spectroscopic windows include BaF2, CaF2, and ZnSe. Hygroscopic materials such as NaCl and KBr are not suitable for this purpose because water will dissolve the window. Silicon is also transparent in the mid-IR region and has great potential for use as a material to construct micro-fluidic devices for FT-IR imaging because etching techniques for silicon wafers are well established and its surface properties can be tuned with self-assembled mono-layers. Other infrared transparent win-dows are often not malleable and specific etching techniques may first need to be developed (26). Furthermore, these crys-tals are often too expensive to be used as a one-off device (a pair of large windows

would cost as much as $320). The ability to create reusable microfluidic devices on these windows would be an important step forward for the wider application of this approach.

Wax-Printed Microfluidic Devices

One of the possibilities for producing microfludic devices is direct wax print-ing. Machines that can print molten wax droplets at precise locations are com-mercially available. Previous studies used wax printers in one of two ways, either to create the master, which was then used to cast PDMS devices to obtain the nega-tive design of the printed features (27,28), or printing the device on paper to cre-ate paper microfluidics (29,30). Our wax printing approach manufactures micro-fluidic devices with free-flowing chan-nels directly without the need for casting PDMS over the print. We have applied

this method to create various microflu-idic devices on a CaF2 substrate. The procedure is relatively straightforward. Microfluidic devices are first designed and programmed into the computer that operates the microdrop machine. Molten wax droplets, each of which has a controllable diameter of 30–70 µm, are printed directly onto the CaF2 window. The CaF2 window can be precoated with a thin layer of polymer to create a hydro-phobic surface when necessary. The ad-jacent molten wax droplets join together and solidify to form a wax wall. Figure 2 shows a photograph of a T-junction microfluidic device created by the wax printing method.

A spacer is added that determines the depth of the channel, which is also the pathlength of the measurement. The microf ludic channel is created when another CaF2 window is pressed on top and held together by screws, for ex-ample. Experiments can be conducted immediately after the printing process, and the infrared-transparent windows can be reused because the wax channels can be removed easily. Depending on the complexity of the design, the printing time is typically less than 10 min. New microfluidic devices can be modified and created in a matter of minutes. The size of the wax droplet is on the order of 50 µm and the machine has an accuracy of 40 µm, which defines the resolution of the microfluidic device. So far, we have only experimented using wax that is vul-nerable to many organic solvents and oil. However, waxes that are highly chemi-cally resistant are also available; we plan to test these and present the results in the future.

Transflection mode

In transf lection mode, the sample is placed on an infrared-ref lective sub-strate surface where the IR radiation passes through the sample, is reflected off the surface of the substrate, and passes through the sample again before being collected with the sample objective. For microfluidic applications, the advan-tage of this approach is that only the top surface needs to be infrared transparent. When an open channel is used (that is, when the top surface is not covered and is open to air), there is no need to construct

1 mm

PDMS

10

5

0

-5

Oil

ATR element

IR light

Oil

Water

Ab

sorb

an

ce

Wavenumber (cm-1)

0.3

0.25

0.2

0.15

1000 1100 1200 1300 1400 1500 1600 1700 1800

Water droplet

Figure 3: Top figure: ATR FT-IR image of oil with water droplets flowing inside microfluidic channels

taken with a snapshot at less than 50 ms scanning time with a frame rate of approximately 18 Hz.

Imaging area to right of the FT-IR image: schematic diagram showing the side view of the moving

water droplet in oil in the microfluidic device on the ATR element. Bottom figure: The blue line

represents the extracted averaged ATR spectrum from the moving water droplet region and the

red line represents the extracted averaged ATR spectrum from the oil region.


the microfluidic device in an infrared-transparent material. The main require-ment is that the bottom of the channel is infrared reflective, which can be easily achieved. However, the thickness con-straint that applies in transmission mode measurement is more severe because the pathlength is twice the thickness of the f luid. Nevertheless, such an approach was used in the study of biofilms and live cells in an open channel setting (31).

Two-Phase Segmented Flow In comparison to laminar f low, seg-mented flow and droplet flow offer the possibility to perform high-throughput studies without increasing the size or complexity of the microfluidic device (32). Although each droplet or segment is compartmentalized by the immiscible inert phase, each segment can be consid-ered as individual experiments.

FT-IR imaging of droplets or segments can be captured easily when they are sta-tionary. The applications of segmented flows include protein crystallization, live cells in droplets, and other slow processes. Many of these research ideas are yet to be realized in combination with FT-IR imag-ing. One of the main challenges in imag-ing segmented flows is when one wants to capture the droplet or segments while they are moving. The acquisition time for a typical FT-IR imaging measurement is on the order of seconds. Although this imaging speed is already a great improve-ment from the early FT-IR imaging sys-tems; it is often not fast enough to capture the moving droplets. Fortunately, through optimization of the data acquisition pro-cess, FT-IR imaging of moving segments or droplets in microfluidic channels has been demonstrated (33). Traditionally, the acquired data in an FT-IR imaging measurement are the average of several scans to improve on the signal-to-noise ratio. (In theory, the signal-to-noise ratio is improved by the square root of the number of scans taken.) However, to capture droplet flow, only one scan can be collected. The time taken for one scan is governed by the spectral range and spectral resolution set in the experiment as well as the number of detector pixels used. For an imaging experiment with a 64 × 64 pixel array, 8 cm-1 spectral resolution, and 4000–900 cm-1 spectral

range, the scanning time is approximately 600–700 ms. With current technology, one needs to reduce the amount of data collected to improve this speed. For ex-ample, most of the spectral information is contained in the so-called fingerprint region of the infrared spectrum (between 1800 and 500 cm-1). Because the detec-tion limit for the FPA detector is around 900 cm-1 or ~1000 cm-1 when CaF2 is used as the substrate material, there is an opportunity to reduce the amount of data collected without losing significant

chemical information by reducing the spectral range to 1800–1000 cm-1. This can increase the speed of the scan four-fold. By reducing the spectral resolution from 8 cm-1 to 16 cm-1, 32 cm-1, or even 64 cm-1, the signal-to-noise ratio will be improved and the spectral bands will be broader while the speed of the scan can be doubled, quadrupled, or even octupled. Together, this brought the scanning time down to well below 100 ms (33).

First, we attempted imaging of droplet flow using the ATR approach. A micro-


fluidic chip with a “T-junction” design was mounted on the measuring surface of the ATR element (Si was used in this case). The surface of the Si was pre-treated to increase the hydrophobicity. The oil (FC-40) and water were intro-duced at f low rates of 2 µL/min and 1 µL/min, respectively. The result is shown in Figure 3. The images of oil have shown that the water droplets flowing in the oil have been captured. In the re-gion in which a water droplet is present, the oil absorbance is lowered. However, spectra extracted from the water droplet region have shown a high absorbance of oil while the water absorbance was very low (see spectra in Figure 3). The reason for this observation is that when water droplets are moving at high speed inside the channel, there is a thin layer of oil in between the water droplet and the ATR element (see Figure 3). Because in ATR

measurements only the layer of several micrometers from the surface of the ATR element is detected, the resultant spectral bands were contributed mostly by the oil layer on the surface of the ATR element. On the other hand, the spec-trum of pure water can be obtained from the imaging data when the water droplet is stationary. Comparing the absorbance of the oil in the water droplet region to the bulk oil, the thickness of this oil layer can be calculated using the following equation (34,35):

In 1A(t)A( )

2tdp∞

[1]

where A(t) is the absorbance of the oil at the water droplet region, t is the oil film thickness, A(∞) is the absorbance of the oil at the region without the water drop-let, and dp is the depth of penetration.

The thickness of the oil layer is calculated as 790 nm.

To capture the spectrum of water more clearly in the segment, imaging in trans-mission mode needs to be used. Figure 4 shows the image, the schematic dia-gram, and the extracted spectra of a water droplet flowing in oil in a wax-printed microfluidic device with a pathlength of 25 µm. The absorbance of water is far more pronounced compared to the spec-trum extracted from the ATR measure-ment shown in Figure 3. However, as dis-cussed in the transmission mode section, the large pathlength could lead to some parts of the spectral region becoming inaccessible. In this case, the spectral re-gion in which oil absorbs IR light strongly (1100–1350 cm-1) is not accessible in the oil-rich region of the image. This is in contrast to the spectra extracted from the ATR imaging measurement, in which the absorbance of all spectral bands was less than 0.8, the value below which analysis can be quantitative. On the other hand, a large amount of the spectral range remains accessible in the water droplet region (1600–1000 cm-1). We have dem-onstrated previously that, despite the use of only one scan per image, the presence of protein can be detected at the ~1 mM level in the water segment in transmission mode by observing the amide II band at 1560 cm-1 (36).

Reactions

One of the potential benefits of combin-ing FT-IR imaging with microfluidics is the in situ study of chemical reactions inside the channel. This allows for op-timization of reaction conditions to ob-tain better yields, or understanding the diffusion and reaction kinetics inside the microfliudic device. This technique can be developed into a tool for chemical detection in microreactors for studying the effect of changing parameters to the overall efficiency. One of the examples (25) that demonstrated this potential was the observation of isotopic exchange between water and D2O forming HDO (semiheavy water). The spectral bands of H2O, D2O, and HDO are readily distin-guishable. Because FT-IR measurements can be quantified, the concentrations of reactants and products at different points of the devices can be obtained. Another

1 mm

Oil

CaF2

CaF2

IR light

Water droplet

1.5

Ab

sorb

an

ce

OilWater1

0.5

0

Wavenumber (cm-1)

1100 1200 1300 1400 1500 1600 1700 1800

Figure 4: Top figure: Transmission FT-IR image of water droplets in oil flowing inside microfluidic

channels taken with a snapshot at less than 50 ms scanning time with a frame rate of approximately

18 Hz. Right of the FT-IR image: schematic diagram showing the side view of the moving water

droplet in oil in the CaF2 sandwiched wax-printed microfluidic device. Bottom figure: The blue

line represents the extracted transmission spectrum from the moving water droplet region and

the red line represents the extracted transmission spectrum from the oil region.

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possible experiment is a reaction in a two-phase system in which one of the re-actants is dissolved in the oil phase while the other reactant is dissolved in aqueous phase (37). The resultant effect is that the reaction can only happen at the interface between the two fluids. Diffusion profiles and the formation of product in such sys-tems can be monitored simultaneously using the FT-IR imaging approach (37). This detection approach is set to benefit automation of reactions and other pro-cesses in microreactors (38).

Conclusions In this article, we have discussed a meth-odology that permits the in situ chemical imaging of flows in microfluidic chan-nels using FT-IR spectroscopic imaging that does not require added labels or dyes. This inherent chemical specific-ity of FT-IR imaging significantly adds to the detection capabilities of flows in microfluidic devices because it obtains quantitative chemical information as a function of space and time. This chemi-cal imaging methodology has wide appli-cability to the study of dynamic systems ranging from the analysis and modeling of mixing in laminar flows to studies of reactions in segmented flows and sepa-rating live cells in moving droplets. We hope that this article can stimulate fur-ther applications of FT-IR spectroscopic imaging to study processes and reactions in microfabricated devices and micro-reactors because this methodology has great potential for in situ fast chemical analysis of microfluidic flows.

Acknowledgment SGK acknowledges research funding from the European Research Council under the European Community’s Seventh Frame-work Programme (FP7/2007-2013)/ERC advanced grant agreement no. [227950].

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Dr. Ka Lung Andrew Chan is a

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For more information on this topic, please visit our homepage at: www.spectroscopyonline.com

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CHEM & BI

POWERING INNOVATIONS IN


The synthesis of most chemicals requires a cata-ly t ic process. As a resu lt , cata lysts are of ten studied with the goal of improving their prop-

erties and catalytic behavior. Spectroscopy is a valu-able tool to characterize the surface of sol id (het-erogeneous) catalysts and also can be useful for the determination of reaction intermediates and other adsorbed species. Raman spectroscopy is par t icu-larly usefu l for studying cata lysts because Raman spectra can be obtained under a wide range of con-ditions (at high pressures and at temperatures above 1000 ∘C, by the use of the appropriate excitation wave-length), which makes it possible to use Raman spec-troscopy to characterize catalysts during a reaction. Determining catalyst performance (such as conversion or selectivity) during a reaction, at the same time that the catalyst is characterized, is the concept of the ope-rando Raman methodology (1–6).

Over the last decade, operando Raman spectroscopy has been applied successfully to the study of several cat-alytic systems, in both liquid- and gas-phase processes. Such studies have provided a better understanding, and subsequent improvement, of various catalytic processes.

The aim of this article is not to provide a detailed re-view of the method, but rather to present brief ly the opportunities and current progress of operando Raman spectroscopy through some examples based on the au-thors’ work.

Look, But . . . How?

One of the critical issues in performing operando ex-periments is to correctly design the Raman cell, because it has to perform like a catalytic reactor and meet the optical requirements for spectroscopy. The Raman cell and the reaction conditions must prevent any mass or heat transfer limitations and the contribution of non-catalytic reactions such as gas-phase reactions. Thus, conventional cells cannot be used to perform catalytic tests. Traditional cells are good for in situ studies, be-cause the sample is fully “aware” of the presence of the gas, but most in situ Raman cells are designed in such a way that not all the gas f lowing through it interacts with the sample (catalyst). Figure 1 shows the home-made operando reactor designed by our group that was used to perform the operando experiments discussed in this article. Essential ly, it is a f ixed-bed catalytic

M. Olga Guerrero-Pérez and M.A. Bañares

Operando means working, thus, this technique refers to the combination of a characteriza-tion study of the surface of a catalyst at the same time that the activity is being monitored. This approach, which permits the simultaneous characterization of both parameters in a single experiment, facilitates uncovering the relationships between structure and activity. Such infor-mation is critical to improving the performance and formulation of catalysts. We illustrate the possibilities of operando Raman spectroscopy with four examples.

Observing Heterogeneous Catalysts While They Are Working Using Operando Raman Spectroscopy


reactor with walls that are optically appropriate for Raman spectros-copy. To prevent the participation of homogeneous reactions, the re-actor was designed to minimize gas-phase activation of reactants (by not having any void volume). Thus, the operando reactor makes it possible to obtain Raman spectra of catalysts and genuine catalytic data. Figure 2 shows the results obtained for sev-eral catalysts at different tempera-tures in the operando reactor and a lso in a convent iona l f ixed-bed cataly tic reactor; the activity and selectivity obtained in both reac-tors is essentia l ly the same, thus proving the validity of the catalytic tests performed during the operando Raman experiments in this home-made reactor cell.

When the Active Phases Are

Sensitive to the Environment

There are many cases in which the active phases of a catalyst form, or, at least change, during react ion. Such phases may not be present before or af ter catalysis, but only during catalysis. The following ex-amples il lustrate two cases, one in which the reaction conditions shape the working catalyst structure, and one in which we monitored t he preparation of the active phase.

Case I: VSbO4 Active Phase

During the Propane

Ammoxidation Reaction

Activating alkanes to obtain com-mod it y chemica ls i s one of t he major challenges the chemical in-dustry must solve in the coming yea rs . T he i nterac t ion bet ween surface antimony oxide, with very weak Raman bands, and surface va-nadium oxide species, with Raman bands at 1020 and 900 cm-1 (Figure 3, spectrum of dehydrated sample), takes place under reducing or non net-oxidizing environments (such as ammoxidation reaction condi-tions) leading to the formation of the trirutile VSbO4 phase, charac-terized by a broad Raman band at 840 cm-1 and segregated α-Sb2O4, as shown by the spectra taken dur-

ing ammoxidation (Figure 3). The cata lyst is select ive to acr yloni-trile (yield close to 30%) when the trirutile band is intense, indicative that VSbO4 is present on the surface of the catalysts. The interaction be-tween Sb and V is partially reversed upon reoxidation, where reduced vanadium oxide species segregate as surface V5+ species, characterized by a band near 1024 cm-1 (Figure 1, reoxidized sample). Thus, operando Raman spectroscopy uncovers the

redox c ycle ta k ing place on t he VSbO4 active phase during propane ammoxidation (Figure 4) (7–9).

Case II: Ni-Mo

Hydrotreatment Catalysts

Ni-Mo–based catalysts are promising for hydrodesulfurization reactions, which are important processes in the oil refining industry. Hydrode-sulfurization eliminates sulfur and other contaminants from fossil fuels and intermediate petroleum distil-

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lates. Figure 5 shows representative Raman spectra obta ined during sulf idation of Ni-Mo–oxide based

catalysts (10). At the initial sulfida-tion stages, below 300 °C, oxysul-fides and less-reduced molybdenum

sulf ide phases (MoS3) are appar-ent. The lack of Raman features at 300 °C during the sulfidation process is probably a result of a very broad distribution of states, because Raman bands of nanocrystalline MoS2 be-come apparent at 400 °C. Thus, the spectra show that there is a partial sulfidation process at temperatures up to 300 °C, and that an important rearrangement happens before the formation of an incipient and defec-tive MoS2 structure that is beneficial to hydrodesulfurization activity.

Understanding Deactivation ProcessesGiven that react ions may lead to progressive deact ivat ion of cata-lysts, the simultaneous determina-tion of structure and activity offers the opportunity to understand the deactivation phenomena and infer the nature of the act ive site. The examples presented below illustrate this possibility.

Case III: Ce-V-O–Based

Catalysts During Ethane

Oxidative Dehydrogenation

Understanding the mechanism and ac t ive phases of C e-V- O –based catalysts is very important, because both vanadia and ceria are used for many catalytic applications. It has been reported that ceria-supported vanadia cata lysts form CeVO4 at lower temperatures than upon calci-nation in air (11). This is because of the redox cycle during the reaction. The redox cycle periodically reduces ceria sites, promoting the solid-state reaction to form CeVO4 (an irrevers-ible reaction), with the subsequent deactivation of the catalysts. Mar-t inez-Huerta and col leagues (11) monitored the transformation of surface vanadium oxide species on ceria into CeVO4 during an ethane oxidative dehydrogenation reaction. That study detected how the cata-lysts deactivated at reaction temper-atures above 500 °C; the operando Raman–gas chromatography (GC) study shows an incipient formation of CeVO4 on the surface of catalysts with no appreciable deactivation at

Catalyst

Operando reactor

Operando system

Thermocouple well

Inert packing

On-line gas chromatographRaman system

Gas feed system

Vent

Heat screen

Heating element

NH3

O2

C3H8

He

Temperature controller

Figure 1: An operando Raman–gas chromatography setup. Adapted from reference 9 (with permission).

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crylic

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%)

40

30

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60

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40

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4Mo5V4Nb0.5Te0.5 Operando12Mo5V4Nb0.5Te0.5 Operando

4Mo5V4Nb0.5Te0.5 Fixed-Bed12Mo5V4Nb0.5Te0.5 Fixed-Bed

4Mo5V4Nb1 Operando8Mo5V4Nb1 Operando

12Mo5V4Nb1 Operando4Mo5V4Nb1 Fixed-Bed8Mo5V4Nb1 Fixed-Bed

12Mo5V4Nb1 Fixed-Bed

4Mo5V4Nb1 Operando8Mo5V4Nb1 Operando

12Mo5V4Nb1 Operando4Mo5V4Nb1 Fixed-Bed8Mo5V4Nb1 Fixed-Bed

12Mo5V4Nb1 Fixed-Bed

4Mo5V4Nb0.5Te0.5 Operando12Mo5V4Nb0.5Te0.5 Operando

4Mo5V4Nb0.5Te0.5 Fixed-Bed12Mo5V4Nb0.5Te0.5 Fixed-Bed

375 400 425 450 350 375 400 425 450

Temperature (o C) Temperature (o C)

Propane conversion (%) Propane conversion (%)

00 50403020100

Figure 2: Propane conversion vs. temperature and selectivity to acrylic acid for several catalysts

obtained in a conventional fixed-bed reactor and in an operando reactor. Propane partial

oxidation conditions: C3H8/O2/H2O/He = 12.5/20.4/15.9/51.2; 4800 h−1; 0.2 g of catalyst. Adapted

from reference 13 (with permission).


460 °C. The operando study (Figure 6) shows that the Raman bands of CeVO4 become sharper during reac-tions at temperatures greater than 500 °C. This t rend is consistent with a decrease in the exposure of the active sites rather than with a change in the structure of the active phase. The Arrhenius plots of activ-ity data measured in the operando Raman cell (Figure 6) show that the apparent activation energy does not change signif icant ly as the solid-state react ion t ransforms cer ia-supported vanadium oxide species into CeVO4. The Arrhenius plots underline a decrease in the number of active sites but not a change in the nature of the active sites. These data lead to t he conclusion t hat V-O-Ce bonds present in both the fresh (ceria-supported vanadia) and aged (CeVO4) catalysts are directly related to the active sites, and that the redox cycle is related to the ce-rium ions at the interface with vana-dia. Figure 6 (right) illustrates how the progressive interaction between cer ia suppor t and sur face vana-dium oxide species stabilizes Ce3+ ions at the vanadia–ceria interface. Af ter sharing these data, Sauer’s and Freund’s groups performed a detailed experimental and density functional theory (DFT) study of this interaction that showed that t he preferred inter face bet ween dispersed vanadia and ceria sup-port involves reduced Ce3+ ions in the V-O-Ce bonds and confirmed that the preferred oxidation state for vanadium is V5+, which is nearly impossible to reduce (12).

Case IV:

Multioxide Mo-V-Nb-Te-O

Catalysts for the Partial Oxida-

tion of Propane into Acrylic Acid

The selective oxidation of propane into acrylic acid is an interesting route for alkane valorization. The Mo-V-Nb-Te-O catalytic system is active in partial oxidation reactions of propane. Tellurium is a critical component, the role of which re-cent ly has been uncovered using operando Raman–GC (13). Oper-

ando Raman–GC shows that the shape of the spectra changes dras-tically when the temperature reac-tion is increased to 375 °C (Figure 7). Below that temperature, Raman bands near 815 and 380 cm−1 as-signed to Mo–V–O structures and bands near 1000 cm−1 assigned to MoOx or VOx dominate the spec-t r a . I n add it ion, R a ma n ba nd s near 760 and 230 cm−1, assigned to A lVMoO7 s t r uc tures , ca n be detec ted a long w it h t he Ra ma n

band near 880 cm−1, assigned to an Mo5O14-type structure. Conversely, Raman bands near 960, 780, and 237 cm−1 dominate the spectra when the reaction temperature reaches 375 °C; such Raman bands are in-dicative of a distorted MoO3 oxide with some minor amounts of va-nadium species (14). The amount of such an MoO3 structure is not very large, because no X-ray dif-fraction (XRD) pattern for a simi-lar structure was detected, but its

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bands dominate the Raman spectra because this phase possesses a very high Raman cross-section and Raman spectra uncover important changes at the nanometer scale during the reaction. In addition to monitoring

SbVO4

Sb2O4

V=O

Reoxidised

Ammoxidation

Dehydrated

480 o C480 o C

f

d

c

b

a

e420 o C

420 o C

400 o C

400 o C200 o C

200 o C

30 20 10

Acrylonitrile

Acetonitrile

Propylene

CO2

CO

Yield (%)

4,6

4,91,4

5,28,1

4,3

2,61,0

4,14,9

2,4

10,918,1

22,0

29,2

Raman shift (cm-1)

0 9001100 700 500 300 100

Figure 3: Raman spectra of Sb–V–O/Al2O3 catalyst during a propane

ammoxidation reaction: (a) dehydration at 200 °C; (b) ammoxidation

at 200 °C; (c) 400 °C; (d) 420 °C; (e) 480 °C; (f) reoxidation at 440 °C.

The corresponding yield values are presented in the left panel. Reaction

conditions: 200 mg of catalyst, total flow 20 mL/min; feed composition

(% volume); C3H8/O2/NH3/H2O/He (9.8/25/8.6/56.5). Adapted from

reference 7 (with permission).

VSbO4 VOx

Sb2O4 VSbO4

Sb5+

V5+

Sb5+ V3+

Structuralcycle

Redoxcycle

Figure 4: Possible catalytic redox cycle of vanadium and migration

cycle of antimony during propane ammoxidation in V-Sb-O catalysts.

Adapted from reference 9 (with permission).

NiMo/50ASA

MoS2

MoS3

404

435 320

540

450

348

325

213

377

280

220

10 min, 300 oC, H2S

Raman shift, cm-1

10 min, 200 oC, H2S

10 min, 100 oC, H2S

4h, 400 oC, H2S

700 600 500 400 300 200 (g578)

Oxysulfides

Figure 5: In situ Raman spectra at different sulfidation stages of

NiMo–50ASA. Adapted from reference 10 (with permission).

log

Co

nve

rsio

n

1.5

OO V5+ O

O

O

O

O O O

O V VO

O

1

3

4

52

O

O O n

O

V

V

O

O O O

O O

OCeO2

CeVO4

CeO2

CeO2

CeO2

CeO2CeO2

Ce3+

Ce3+

Ce3+First run

Second run

1.1

0.7

0.3

-0.1

-0.50.0012 0.0013 0.0014 0.0015

1/T (K)

Figure 6: Left: Arrhenius plot of ethane conversion vs. reaction temperature

in the operando fixed-bed reaction cell. Right: Qualitative illustration of

dynamic states of the V5+/CeO2 system during the incipient and extensive

formation of CeVO4. Adapted from reference 11 (with permission).

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changes occurring in the Nb–Mo–V–O st ructures dur ing propa ne ox idat ion, operando Raman–GC experiments show the formation of coke because bands appearing in the 1200–1650 cm−1 region are at-tributed to carbon deposits with sp2 hybridization.

A similar operando Raman–GC experiment was performed with a catalyst doped with tel lurium. As Figure 8 shows, the addition of a small amount of Te to the Mo-V-Nb oxide system inhibits the deactiva-tion of the catalyst by its rearrange-ment into distorted MoO3 structures and the bui ldup of carbonaceous deposits. In this case, Raman bands in the 900–1020 cm−1 range and the Raman bands near 820 and 370 cm−1 of dispersed oxides are ap-parent during a reaction at 350 °C. Such dispersed ox ide st ructures blend into distorted rutile structure phases as the reaction temperature increases (to 375–450 °C) and are characterized by a broad Raman sig-nal near 800 cm−1. Thus, the study demonstrated that tel lurium dop-ing generates highly distorted rutile structures during the reaction that are capable of inhibiting the forma-tion of MoO3 crystallites under re-action conditions and improves the performance of these cata lysts to achieve sufficient performance.

Conclusions

The operando Raman methodology combines structural and catalytic measurements in a single experi-ment. Because the molecular struc-ture of a catalyst depends on its spe-cific environmental conditions, this combination is critical to be able to rel iably assess structure–activ ity relationships at the molecular level. The examples presented here illus-trate that this methodology can fol-low the dynamic states of catalysts, which are determined by the reac-tion. The formation of active phases during the reaction and their even-tual deactivation are directly linked to kinetic data. In addition, it has been shown that Raman spectros-copy uncovers important changes

at the nanometer scale during reac-tions, even though those changes are not revealed by XRD. In sum-

mary, the state of a catalyst is de-termined by the reaction conditions. This could be expressed borrowing

450oC

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450

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ture

(oC

)

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400

375

350

200

0 10 20 30 40 50 60

400oC

375oC

350oC

200oC

25oC

2000 1600 1200 800 400

Raman shift (cm-1) % Conversion/Selectivity

Figure 7: Operando Raman–GC spectra during the selective oxidation of propane on 12Mo5V4Nb1;

Left: Raman spectra obtained during reaction at the temperature indicated; right: simultaneous

activity and selectivity data obtained during Raman spectra acquisition. C3H8/O2/NH3/H2O/He

= 12.5/20.4/15.9/51.2; 4800 h−1; 0.2 g of catalyst. Adapted from reference 13 (with permission).

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the expression by the Spanish phi-losopher Ortega y Gasset , “I am I plu s my c i rc u mst a nce s .” T he exa mples presented here tel l us that the cata lyst is itsel f and its circumstances.

References

(1) B.M. Weckhuysen, Chem. Commun.

97–110 (2002).

(2) M.A. Bañares, M.O. Guerrero-Pérez,

J.L.G. Fierro, and G.G. Cortéz, J. Mater.

Chem. 12(11) 3337–3342 (2002).

(3) M.O. Guerrero-Pérez and M.A.

Bañares, Catal. Today 113, 48–57

(2006).

(4) V. Calvino-Casilda and M.A. Bañares,

Catalysis 24, 1–47 (2012).

(5) M.A. Bañares, Adv. Mater. 23, 5293

(2011).

(6) I.E. Wachs and C.A. Roberts, Chem.

Soc. Rev. 39, 5002 (2010).

(7) M.O. Guerrero-Pérez and M. A. Ba-

ñares, Chem. Commun. 1292–1239

(2002).

(8) M.O. Guerrero-Pérez and M. A.

Bañares, J. Phys. Chem. C 111, 1315

(2007).

(9) M.O. Guerrero-Pérez and M. A.

Bañares, Catal. Today 96, 265

(2004).

(10) M.O. Guerrero-Pérez, E. Rojas, A.

Gutiérrez-Alejandre, J. Ramírez,

F. Sánchez-Minero, C. Fernández

Vargas, and M.A. Bañares,

Phys. Chem. Chem. Phys. 13,

9260 (2011).

(11) M.V. Martínez-Huerta, G. Deo, J.L.G.

Fierro, and M.A. Bañares, J. Phys.

Chem. C 112, 11441 (2008).

(12) M. Baron, H. Abbott, O. Bondar-

chuk, D. Stacchiola, A. Uh, S. Shai-

khutdinov, H.-J. Freund, C. Popa,

M.V. Ganduglia-Pirovano, and J.

Sauer, Angew. Chem. Int. Ed. 48,

8006 (2009).

(13) R. López-Medina, J.L.G. Fierro,

M.O. Guerrero-Pérez, and M.A.

Bañares, Appl. Catal. A 406, 34

(2011).

(14) M.A. Bañares and S.J. Khatib, Catal.

Today 96, 251 (2004).

M. Olga Guerrero-Pérez is with

the Department of Chemical Engineering

at the University of Malaga in Malaga,

Spain. Please direct correspondence to:

[email protected].

M.A. Bañares is with the Catalysis

and Petrochemical Institute of the

Consejo Superior de Investigaciones

Científicas (CSIC), in Madrid, Spain. ◾


450oC

425oC

400oC375oC350oC

25oC

450

Tem

pe

ratu

re (

oC

)

425

400

375

350

200

0 10 20 30 40 50 60

% Conversion/Selectivity

2000 1600 1200 800 400

Raman shift (cm-1)

Figure 8: Operando Raman–GC spectra obtained during the selective oxidation of propane on

12Mo5V4Nb0.5Te0.5. Left: Raman spectra during the reaction at the temperature indicated. Right:

Simultaneous activity and selectivity data obtained during Raman spectra acquisition. Reaction

conditions: C3H8/O2/H2O/He = 12.5/20.4/15.9/51.2; 4800 h−1; 0.2 g of catalyst. Adapted from

reference 13 (with permission).

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Summer is long gone now and as our minds focus on the luscious fall foliage and long, cold winter months ahead, we should also turn to the positive feelings that come from hav-

ing new problems to solve and the ability to productively contrib-ute to their solutions. This year’s Eastern Analytical Symposium (EAS), being held November 12–15 in Somerset, New Jersey, will offer those positive feelings and a wealth of knowledge to help you find the solutions you need. To highlight the invited symposia in spectroscopy and related fields we have asked some of the chairs of the invited sessions to briefly describe their intentions as they pulled together well-known and well-respected speakers for their chosen topics. My hope, as the 2012 EAS program chair, is that this synopsis will encourage you to come, see, hear, and enjoy the directions that spectroscopy has taken over the past year. This is with the goal that once you return from EAS in November, you can use your new-found knowledge to energize your own laboratory and solve problems.

Mass SpectrometryThis year, Fred McLafferty, of Cornell University, is being recog-nized for his many transformative innovations over the last half century with the Award for Outstanding Achievements in Mass Spectrometry, to be given at a symposium in his honor. From de-veloping electron-capture dissociation to offering fundamental understanding of gas-phase-rearrangement phenomena, McLaf-ferty has been a towering figure in the field. Beyond his more than 500 publications on all aspects of the technique, the hundreds of colleagues McLafferty has trained over seven decades, many of whom have themselves made major contributions in mass spec-trometry (MS), make his impact on the field almost unparalleled. Several former students will present in this symposium, including Neil Kelleher of Northwestern University, Gary Valaskovic of New Objective, Inc., and Edward Chair of Life Sciences Consulting, Inc. Among the topics to be discussed are the latest technologies for electrospray MS of whole proteins in the gas phase (the so-called

“top down proteomics”), and recent advances in application of this technology to the area of expression genomics.

A two-session mini symposium titled “Mass Spectrometry of Large and Biomolecules” will feature leaders and emerging sci-entists from academia, industry, and instrument manufacturing. A wide array of recent developments that overcome challenges faced when using MS for the study of large and biomolecules will be discussed, including method development and applications for proteomics and metabolomics, as well as the analysis of oligo-nucleotides, polymers, and supramacromolecules. For example, Martin Gilar of Waters Corporation will discuss liquid chroma-tography (LC) separations for complex mixtures of oligonucle-otides, peptides, and glycopeptides. Kimberly Ralston-Hooper of Duke University will present proteomic applications in environ-mental toxicology. Jiong Yang of Merck will speak on modified oligonucleotide sequencing for identity confirmation of phospho-rothioate-containing siRNAs. Chrys Wesdemiotis of the Univer-sity of Akron will discuss method development for MS analysis of synthetic polymers and supramacromolecules. The effect of peptide structure on matrix-assisted laser desorption–ionization time-of-flight mass spectrometry (MALDI TOF-MS) signal inten-sity will be presented by Kevin Owens of Drexel University. Sarah Trimpin of Wayne State University will put forth new ionization approaches, Gary Kruppa of Bruker Daltonics, Inc., will touch on applications using MALDI-TOF for biopharmaceutical quality control, and Mark Cancilla of Merck will acquaint the audience with MS-based assays for the characterization of oligonucleotides.

NMRJeffrey A. Reimer of the University of California at Berkeley is the 2012 recipient of the EAS Award for Achievements in Magnetic Resonance. This award recognizes his contributions to solid-state nuclear magnetic resonance (NMR) and magnetic resonance im-aging (MRI), in catalysis, electrochemistry, polymer science, and semiconductor physics. Joining Reimer are three distinguished

Mary Ellen McNally

From November 12 to 15, 2012, as in the preceding 50 years, the Eastern Analytical Symposium will bring a rich assortment of potential solutions and collaborations to its attendees and contributors.

Energize Your Laboratory at the 2012 Eastern Analytical Symposium

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FTIR Microscopy is among the most powerful tools in the identifica-

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molecule has a unique infrared signature providing great specific-

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nents in mixtures can also be determined by collecting infrared area

images of the product in question. Examples will be shown that

demonstrate the effectiveness of FTIR Microscopy for identification,

quantification and distribution of materials on a microscopic level.

These examples will be collected with a simple to use and fully auto-

mated FTIR microscope.


n Demonstration of the simplicity of FTIR Microscopy for routine

and advanced applications

n Specific examples of mapping for specific molecular distribution

n Ease-of-use software for simple to advanced measurements

For questions, contact Kristen Farrell at [email protected]

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Applications of Raman Spectroscopy

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n The importance of Raman

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biochemists, or anyone interested in

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biomedical diagnostics.

LIVE WEBCAST: Wednesday, October 17, 2012 at 1:00 pm EST

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EVENT OVERVIEW

In recent years, Raman spectroscopy has gained widespread

recognition in biomedical research as a principal diagnostic

and screening tool. This presentation will begin with an over-

view of the uses of Raman in a variety of biomedical applica-

tions, and then discuss one of the most active research areas

for Raman biospectroscopy: cancer detection, focusing on

research at the University of Utah on the development of a

surface enhanced Raman scattering (SERS)–based immuno-

assay array for pancreatic cancer marker screening.

Pancreatic adenocarcinoma is the fourth most common

cause of cancer deaths in the US with a 5-year survival rate

of 4%, the lowest of any cancer. Early diagnosis of pancre-

atic adenocarcinoma remains elusive due to the asymptom-

atic development of the disease and the advanced disease

state required for radiological and histopathologic determi-

nation. However, a proof-of-principle immunoassay panel

using SERS has been developed. The SERS assay uses gold

nanoparticles conjugated with both a secondary antibody

and a Raman reporter molecule as the assay label. Matrix

metallopeptidase 7 (MMP-7), a relevant and well-estab-

lished marker for pancreatic adenocarcinoma, was used to

develop the proof-of-concept marker panel. We will discuss

the design and implementation of this first generation SERS

array for pancreatic adenocarcinoma and its comparison to

current clinical diagnostics.

For questions, contact Kristen Farrell

at [email protected]


Presenters:

Dr. Jennifer Granger

Research Scientist

Nano Institute of Utah

Dr. Michael Kayat

Vice President

B&W Tek

Moderator:

Meg Evans

Managing Editor

Spectroscopy


colleagues who will reflect on the connec-tion between basic knowledge and appli-cations of magnetic resonance. Anant K. Paravastu of Florida State University will speak on multidimensional NMR and 13C-13C nuclear dipolar couplings for the structural characterization of designer self-assembling proteins that form biomedi-cally important nanofiber matrices. Alexej Jerschow of New York University will dis-cuss newly discovered long-lived magnetic resonance signals in solids, which may en-able new approaches for the analysis and imaging of hard tissues (such as bone) as well as battery materials. Cecil Dybowski of the University of Delaware will report on NMR of heavy metals with enormous chemical shift ranges, and how measure-ments can be applied to problems such as elucidating the properties of formulations of artists’ paints or the nature of semicon-ducting materials.

Advances in NMR hardware and tech-niques are allowing increasingly rapid identification of metabolites. Two areas are key: first, the development of hyphen-ated techniques such as LC–MS–NMR, and second, the introduction of cryogenic probes. Dr. Steve Cheatham of DuPont Crop Protection has assembled a session entitled “NMR Techniques for Metabolite ID.” The session focus is on applications of these tools toward metabolite identifica-tion. The first two talks in the session will focus on the use of hyphenated techniques, as representatives from both Bruker and Agilent provide perspective and results of the latest technology in the field.

The second two speakers in this session are representatives of the pharmaceutical industry and will provide insight into the practical aspects of metabolite identifica-tion using NMR techniques. While focus-ing on metabolite identification, the struc-ture elucidation techniques to be discussed in the session should prove relevant to a variety of areas including natural product chemistry, food chemistry, and mixture analysis.

Surface Science

Dan Strongin of Temple University has organized a session titled “Environmen-tal Surface Chemistry” that will highlight recent research on redox transformations in the environment. Redox chemistry that occurs between mineral surfaces and

aqueous organic and inorganic species con-tributes to geochemical cycling of metals, to remediation of toxic aqueous environ-mental pollutants, and to processes such as the sequestration of CO2. One talk will focus on the reactivity of ferrous iron with aluminum oxide and montmorillonite clay and the reactivity of these systems toward redox-active species such as hexavalent Cr and U. Another will concentrate on the redox chemistry of Cr(VI) as it applies to the photochemistry of the mineral phases of the small-band-gap semiconductor

FeOOH. A further talk will spotlight how mixtures of binary metal oxides drive redox chemistry relevant to the removal of pollutants from wastewaters. Research on potential redox chemistry involving min-eral phases will highlight the potential of metal carbonation that is relevant to CO2 sequestration.

“Surface Spectroscopy,” organized by Lars Gundlach of the University of Dela-ware, will turn attention to the interaction of molecular adsorbates and solid surfaces. Piotr Piotrowiak of Rutgers University will


show the sensitivity of spectroscopy of a titanate cluster to every atom, although other properties like the density of states show bulk-like characteristics. Graphene, a hybrid between a molecular and a solid state material (being atomically thin in one dimen-sion), is the focus of X-ray photoelectron spectroscopy (XPS) and reflected electron energy loss spectroscopy (REELS) investiga-tions by Brian Strohmeier of Thermo Fisher Scientific. With these techniques, he addresses chemical surface modification, surface impurities, and substrate interaction. Hsuan Kung of the Univer-sity of Delaware will report on a novel, highly controlled route for depositing metal nanoparticles on zinc oxide particles that allows precise control of the surface morphology. Eric Borguet of Temple University will present time-resolved infrared measurements on the water–silica interface to allow for the study of these important materials. Laurel Kegel of the University of Delaware, in discuss-ing studies of plasmonic nanostructures, will emphasize the im-portance of penetration depth and resonance wavelength for the sensitivity of surface plasmon resonance sensors.

Vibrational SpectroscopyAs a workhorse analytical technique in so many industries for such a long time, vibrational spectroscopy might possibly be in danger of being taken for granted. In the session “Bringing Home the Bacon — Vibrational Spectroscopy Gets the Job Done,” or-ganized by Linda Kidder of Malvern Instruments, presentations about out-of-the-box applications of mid-infrared, near-infrared, and Raman spectroscopy will show that there are many new ways

to analyze materials with vibrational spectroscopy. Nancy Jestel of Sabic Innovative Plastics will provide an industrial perspective for using vibrational spectroscopy’s unique capabilities to solve critical analytical problems. The proliferation of multivariate algorithms and their increasingly “routine” application to spectroscopic data has been critical in enabling development of vibrational spectros-copy. Katherine Bakeev of Camo Software will explore data vi-sualization and analysis. Cutting-edge vibrational spectroscopic tools and their applications to chiral drugs and biotherapeutics will be the topic of a presentation by Rina Dukor of BioTools. As Raman spectroscopy has become more “mobile,” it has assumed a new dimension, as will be seen in the presentation focusing on Raman five-component identification from Edita Botonjic-Sehic of Morpho Detection.

A Coblentz Society–sponsored session entitled “Spectroscopy in the Palm of your Hand,” organized by Heinz Siesler of the Univer-sity of Duisburg-Essen (Germany), will provide a new perspective on spectroscopic control of drug-product production and analysis. For example, Benoit Igne of Duquesne University will present a case study in which specific algorithms and analyses of on-line blend data were evaluated to determine their ability to provide quality control of tablets. Douglas Both of Bristol-Myers Squibb (BMS) will describe an approach to designing real-time-release (RTR) testing–based control strategies for commercial manufac-turing and how it relates to and evolves from the quality-by-design (QbD) work performed during development, where the funda-mental understanding of the product’s critical quality attributes were established. Like BMS, Pfizer has also received regulatory approval for RTR-based control strategies, and Steve Hammond will demonstrate why it is beneficial to measure one’s process in real-time. Martin Warman of Vertex will describe a systematic approach to defining the critical steps in making an acceptable product, defining the process space within which we should op-erate to ensuring the process stays within that defined space. His talk will provide a wide range of examples in which spectroscopic techniques have supported QbD and RTR.

ConclusionSpectroscopy is a vast field with diverse uses and results — both fundamental and applied. EAS 2012 offers a full range of spectros-copy sessions, both theoretical and applied. A trip to EAS 2012 will be rewarded with ideas, understanding, and learning, but more importantly with the atmosphere to make connections to others who work at the cutting edge of these spectroscopic technologies. The EAS 2012 full technical program, list of short courses, and registration is available at the following website: www.eas.org


Mary Ellen McNally is the Program Chair of EAS 2012

and a Technical Fellow at Dupont Crop Protection in Newark,

Delaware. Please direct correspondence to: Mary-Ellen.

[email protected]. ◾

www.piketech.com

[email protected]

tel: 608-274-2721

Accessories for analysis of

gas, solid, and liquid samples.

Contact us with your

application requirements.

Complete list of products

available in the new catalog.

Call, or download

your free copy on-line.

Spectroscopy Sampling Solutions

FTIR, NIR and UV-Vis sampling made easier

ON-DEMAND WEBCAST

Register Free at http://www.spectroscopyonline.com/analytical

For questions, please contact Kristen Farrell at [email protected]

Combined Spectroscopy Methods for GeneralAnalytical Services

EVENT OVERVIEW

FT-IR spectroscopy is relied upon in analytical support and

research laboratories for identification of a variety of unknown

materials or characterization analysis. Within these analyses,

however, there are many difficult questions you are probably

being challenged with such as:

n Why didn’t this material pass our quality standards?

n What is the source of the contamination?

n What is the best formulation for this new product?

n Why are these two materials performing differently?

During this webinar, we will show you how you can combine mul-

tiple sampling and spectroscopic techniques in a single, easy to

use, and compact platform. We will also show you how you can

solve your challenges faster and more efficiently, with the trust

and confidence you need on your most critical analysis tools.

Key Learning Objectives

nIdentify materials using FT-IR, FT-Raman and NIR

nIsolate differences between materials quickly and easily

nInvestigate product failures and competitive analyses

nPerform deformulation to check compositional and

processing operations

Who Should Attend

nAnalysts working in

- Pharmaceuticals

- Polymer/plastics

- Forensics

- Art conservation

- Inks/paints/coatings

- Foods/flavors/oils

nAnalytical services/

contract labs/academics

Presenters

Mike Bradley, Ph. D.

Product Manager for FT-IR

Thermo Fisher Scientific

Laura Bush

Editorial Director

Spectroscopy



Product resourcesFluorescence and UV–vis systemHoriba’s Dual-FL system reportedly combines a CCD-based benchtop fluorometer with a built-in UV–vis spectrophotometer. According to the company, the instrument provides spectral rates as fast as 80,000 nm/s and a signal-to-noise ratio of greater than 20,000:1 RMS.Horiba Scientific,Edison, NJ;www.horiba.com

IMS analyzer An ion mobility spectrom-etry (IMS) analyzer from Photonis is designed for simple integration with most mass spectrometers. According to the company, the compact system can be scaled or customized to interface with a variety of instruments to provide simple IMS analysis that can be performed at room temperature. Photonis, Sturbridge, MA;www.photonis.com

Microwave digestionMilestone’s UltraWAVE micro-wave digestion system uses the company’s single reaction chamber technology for use in metals digestions. According to the company, the system uses a single pressurized vessel for all samples, allowing for simul-taneous digestion of up to 22 samples. The system reportedly can accommodate a maximum temperature of 300 °C and pressure of 199 bar. Milestone, Inc., Shelton, CT; www.milestonesci.com/ultrawave.

ICP-MS systemThermo Fisher Scien-tific’s iCAP Q ICP-MS sys-tem is designed to provide increased throughput to enable laboratories to cut analysis times by up to 50%. According to the company, the system features an inter-face that enables one-click setup and allows users to go from standby to perfor-mance-qualified analysis with the push of a button. Thermo Fisher Scientific, Inc., San Jose, CA; www.thermoscientific.com

Analysis of sulfur in gypsumAn application note from Rigaku describes the use of the company’s NEX QC energy dispersive X-ray fluorescence spectrometer in the monitoring of gypsum for quality control during the cement production process. According to the publication, other elements in the gypsum, includ-ing calcium, can also be measured. Applied Rigaku Technologies,Austin, TX;www.rigakuedxrf.com

USP 232 standardsSPEX CertiPrep’s con-sumer safety compliance standards now include USP 232 elemental impu-rities standards. Accord-ing to the company, the standards can be used as a calibration or check standard to verify oral daily dose PDE, parenteral component limit, or parenteral daily dose PDE.SPEX CertiPrep,Metuchen, NJ;www.spexcertiprep.com

Silicon drift detectorEDAX’s thermoelectrically cooled 50-mm2 silicon drift detector is designed for use in its Orbis micro-XRF elemental analyzer system for high-resolution spectral acquisition. According to the company, the system can be useful for those who make measurements on small frag-ments, coatings and deposits on thin substrates (such as ink on paper). biological samples, and trace element analysis using heavy filters to improve sensitivity.EDAX, Mahwah, NJ; www.edax.com

UV polarizersMoxtek’s UV wire-grid polarizers are designed for use at wavelengths as low as 250 nm with high transmission, extinc-tion, and angular aper-ture. According to the company, the product’s materials are metal and glass, making it suitable for harsh environments and demanding applications.Moxtek, Orem, UT; www.moxtek.com

Getting the Most From

Your ICP-MS Instrument

LIVE WEBCAST: Thursday, October 18, 2012 at 8:00 am PST, 11:00 am EST, 15:00 GMT

Register Free at www.spectroscopyonline.com/icpms-software

For questions, please contact Kristen Farrell at [email protected]

EVENT OVERVIEW

Sample analysis is not all about having just good technology. Software

is the most user-interactive feature of an instrument package and as

such greatly influences staff morale, performance, and throughput

capabilities. This complimentary webinar will demonstrate how new

software for ICP-MS can improve laboratory performance by enabling

simple operation and fast start up, full workflow solutions via seam-

less integration with different inlet systems, rapid evaluation of results

from clear and flexible presentation of the analytical data, and reduced

operational costs.

Learn how to:

n Achieve rapid start up and intuitive method development

n Simplify workflow control and analytical reporting for all levels of

users

n Integrate control of different inlet systems and peripherals,

including laser ablation and chromatographic systems

n Build an approval workflow for compliance with regulations such

as 21CFR11

There will also be a 15 minute Q&A session where our Thermo Scientific

ICP-MS and software experts will answer your questions and queries.

Who Should Attend?

n Managers of contract,

government or

manufacturing

laboratories

n Those performing

environmental,

pharmaceutical or food

safety analyses

n Analysts using peripherals,

such as autodilutors,

autosamplers,

chromatographic

techniques, laser ablation

coupled with ICP-MS

instrumentation

Presenters

Lothar Rottmann

ICP-MS Product Manager.

Thermo Fisher Scientific,

Bremen

Julian Wills

Applications Specialist.

Thermo Fisher Scientific,

Bremen

Moderator:

Steve Brown

Technical Editor.

Spectroscopy



ICP-MS systemThe Agilent 8800 triple-quadrupole ICP-MS system is designed to provide improved performance compared with single-quadrupole ICP-MS and to provide MS-MS opera-tion for interference removal in reaction mode. According to the company, the system can be used to analyze elements in life-science, soil, rock, and plant materials. The system reportedly also can be set up to operate like a single-quadrupole ICP-MS system.Agilent Technologies, Santa Clara, CA; www.agilent.com

Long-path gas cellsPIKE’s long-path IR gas cells are designed for analysis of air contami-nants, pure gases, and gas mixtures. According to the company, the fixed-path cells range from 2.4 m to 20 m, and the variable model can be adjusted from 1 m to 16 m. All of the cells reportedly mount rigidly to the baseplate of an FT-IR spectrometer.PIKE Technologies,Madison, WI; www.piketech.com

Microvolume UV spectrophotometerShimadzu’s BioSpec-nano spectro-photometer is designed for fast, reproducible concentration determi-nation of nucleic acids and proteins. The instrument reportedly requires a sample volume of 1 μL (0.2-mm pathlength) or 2 μL (0.7-mm path-length), which is pipetted onto its measurement plate. No standard rectangular cell is needed, although a rectangular cell adapter is available. According to the company, sample mounting, measurement, and cleaning are performed automatically by the instrument, and measurement time is 3 s. Shimadzu Scientific Instruments, Columbia, MD; www.ssi.shimadzu.com

FT-IR microscopeThe Lumos stand-alone FT-IR micro-scope from Bruker Optics is designed for visible inspection and infrared spectral analysis. According to the company, all internal moveable components are motorized and the instrument’s software guides operate stepwise through the process of data acquisition. Bruker Optics,Billerica, MA;www.brukeroptics.com/lumos.html

STATEMENT OF OWNERSHIP, MANAGEMENT, AND CIRCULATION

(Requester Publications Only)

(Required by 39 USC 3685)

1. Publication Title: Spectroscopy

2. Publication Number: 0887-6703

3. Filing Date: 9/28/12

4. Issue Frequency: Monthly

5. Number of Issues Published Annually: 12

6. Annual Subscription Price (if any): $79.95

7. Complete Mailing Address of Known Office of Publication: 131 West First Street, Duluth,

St. Louis County, Minnesota 55802-2065

Contact Person: Peggy Olson

Telephone: (218) 740-6359

8. Complete Mailing Address of Headquarters or General Business Office of Publisher:

2501 Colorado Avenue, Suite 280, Santa Monica, CA 90404.

9. Full Names and Complete Mailing Addresses of

Publisher: Michael J. Tessalone, 485F US Highway 1 S., Ste. 100, Iselin, NJ 08830-3009

Editorial Director: Laura Bush, 485F US Highway 1 S, Ste. 100, Iselin, NJ 08830-3009

Managing Editor: Megan Evans, 485F US Highway 1 S., Ste. 100, Iselin, NJ 08830-3009

10. This publication is owned by: Advanstar Communications Inc., 2501 Colorado Avenue, Suite 280,

Santa Monica, CA 90404. The sole shareholder of Advanstar Communications Inc. is: Advanstar,

Inc., whose mailing address is 2501 Colorado Avenue, Suite 280, Santa Monica,

CA 90404.

11. Advanstar Communications Inc. is a borrower under Credit Agreements dated May 31, 2007,

with various lenders as named therein from time to time. As of June 12, 2012, the agent for the

lenders is: Credit Suisse, Administrative Agent, 11 Madison Avenue, New York, NY 10010.

12. Does Not Apply

13. Publication Title: Spectroscopy

14. Issue Date for Circulation Data Below: August 2012

15. Extent and Nature of Circulation

Average

No. Copies No. Copies of

Each Issue Single Issue

During Published

Preceding Nearest to

12 Months Filing Date

A. Total Number of Copies 22,453 22,715

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Mail Subscriptions Stated on PS Form 3541 20,698 18,196

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(Sum of 15b (1), (2), (3), and (4) 20,718 18,214

D. Non-requested Distribution

1. Outside County Non-requested Copies

Stated on PS Form 3541 1,068 3,534

2. In-County Non-requested Copies

Stated on PS Form 3451 0 0

3. Non-requested Copies Distributed

Through the USPS by Other Classes of Mail 0 0

4. Non-requested Copies Distributed

Outside the Mail 337 686

E. Total Non-requested Distribution

(Sum of 15d (1), (2), (3) and (4)) 1,405 4,220

F. Total Distribution (Sum of 15c and e) 22,124 22,434

G. Copies not Distributed 330 281

H. Total (Sum of 15f and g) 22,453 22,715

I. Percent Paid and/or Requested Circulation 93.65% 81.19%

16. Publication of Statement of Ownership for a Requester Publication is required and will be

printed in the October issue of this publication.

17. Name and Title of Editor, Publisher,

Business Manager, or Owner: Anne Brugman, Audience Development Director

Date: 9/28/2012

I certify that the statements made by me above are correct and complete.

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Bruker Optics 3, 41

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Spectroscopy 1012 2012