New Strategies for Environmental Water Analysis
Bin HuDepartment of Chemistry, Wuhan University,
Wuhan 430072, China
2009.03.03
Outline► Introduction
► Microextraction techniques combined with atomic spectrometry for trace/ultratrace elements analysis in environmental water
► Microextraction combined with chromatographic techniques for environmental water analysis
► Conclusion
The nature water cycle Water covers 70% of the earth's surface and is vital to all living things. Water is always circulating between the earth's surface and the atmosphere in the water cycle.
To well serve sustainable development strategy of utilizing and protecting water resource, it is very important to monitor the quantity of environmental water.
However, water quality monitoring is a difficult task, as the scope of water analysis is inherently broad, encompassing analytical studies involving organic and inorganic contaminants.
Introduction
Environmental Water AnalysisFor studies of inorganic contaminants in water samples, trace elements analysis and elemental speciation protocols for elements such as As, Cr, Hg, Sb, Se and Sn have been receiving considerable attention.
As for organic pollutants, they encompass a diverse group of compounds, including pharmaceuticals, drugs of abuse, personal-care products (PCPs), steroids and hormones, surfactants, perfluorinated compounds (PFCs), flame retardants, industrial additives and agents, and gasoline additives, as well as their transformation products (TPs).
The development of simple, inexpensive, sensitive and rapid analytical methodologies for the quantitative analysis of inorganic contaminants, organic pollutants, their metabolites, and their TPs in environmental waters is very mandatory.
Inorganic contaminants◆Atomic absorption spectrometry► Flame atomic absorption spectrometry (FAAS)► Graphite furnace atomic absorption spectrometry (GFAAS)
◆Atomic emission spectrometry► Inductively coupled plasma optical emission spectrometry (ICP-OES)► Microwave induced plasma optical emission spectrometry (MIP-OES)► Direct current plasma optical emission spectrometry (DCP-OES)► Glow discharge optical emission spectrometry (GD-OES)
◆ Atomic fluorescence spectrometry (AFS)◆ Atomic mass spectrometry► Inductively coupled plasma mass spectrometry (ICP-MS)► Microwave plasma mass spectrometry (MW-MS)► Glow discharge mass spectrometry (GD-MS)◆ Electrochemical methods
Instrumental Methods for Water Analysis
Organic pollutants
◆ Chromatography► Gas chromatography (GC)► high performance liquid chromatography (HPLC)► Super-critical fluid chromatography (SFC)► Electrophoresis
◆ Molecular spectroscopy► Ultraviolet –visible spectrophotometry (UV-VIS)► Fluorescence spectrometry ► Chemiluminescence……
◆ Mass spectrometry
◆……
Instrumental Methods for Water Analysis
Hyphenated Techniques for Elemental Speciation
• The most powerful and effective approach for the elemental speciation.
• These involve the coupling a selective separation with sensitive and element-specific detection.
• For increased quality control, molecule-selective detection can be coupled to separation device.
Why Sample Pretreatment?
Powerful instruments The purpose of sample pretreatment:The purpose of sample pretreatment:
●● Removal of coexisting interferencesRemoval of coexisting interferences●● Preconcentration of the target analytesPreconcentration of the target analytes
Problems:► Very low concentration of analytes► Analyte species highly dependent on time and
space► Complicated matrix, severe matrix effect
One of the key step to the whole analytical procedure
Sample pretreatment
Why Microextraction?
◆Convention methods for sample pretreatment
►high reproducibility, easy to use
► requiring large amount of high-purity organicsolvents
► easily contamination
► prone to be analyte loss
► time-consuming
The development of faster, simpler, inexpensive and more environmentally friendly sample-preparation techniques is an important issue in analytical chemistry
Trends for sample pretreatment
Solventless and Environmental benign
MiniaturizationMiniaturizationVery small amount of Very small amount of sample available sample available
Solid phase extraction (SPE)Solid phase microextraction
(SPME)Liquid phase microextraction
(LPME)Stir bar sorptive extraction
(SBSE)Supercritical fluid extraction
(SFE)……
SPMELPME
SPME, LPME and SBSE are the most attractive ones
Single drop microextraction (SDME)
Sampling modes: direct and head space
LPME Hollow fiber liquid phase microextaction (HF-LPME)
◆LPME is a environmental benign sample preparation techniques
◆High preconcentration factors
◆ Since LPME was first proposed by Liu and his colleagues in 1996,it was accepted immediately by the analytical community. More and more papers was published in different scientific journals in recent years
Liquid Phase Microextraction
Dispersive liquid phase microextraction (DLPME)
MALDI-TOFMSESI-MS (MS)
ICP-IDMS
Schematic representation of direct single-drop microextraction system
Schematic representation of head space single-drop microextraction system
SDME
Popular apparatus
ICP-AESICP-MS
ICP-IDMS
Technical set-up for LPME based on U-shaped fiber
Technical set-up for LPME based on fiber
Membrane based LPME
Dispersive liquid phase microextraction
Sample solution
Extraction solvent,dispersive solvent
Chelating reagentCloudy solution
Organic phase with small volume
Clear aqueous solution
Centrifugation
Detection
Capillary Microextraction
◆CME is a environmental benign sample preparation techniques
◆ CME integrates a number of sample handling operations such as extraction, preconcentration, and sample introduction for instrumental analysis that follows the sample preparation step
◆ Like solid-phase microextraction (SPME), CME is also a simple, inexpensive, easy-to-automate, portable, and time-efficient sample preparation technique
ICP-AESICP-MS
R. Eisert, J. Pawliszyn, Anal. Chem., 1997, 69, 3140H. Kataoka, J. Pawliszyn, Anal. Chem., 1999, 71, 4237
On-line CME-HPLC
On-line CME-ICP-MS
Simple
Rapid
Less sample required
Solvent-free
automation
ICP-AESICP-MS
ICP-IDMS
Extraction materials for CMEGC capillary commercially availableGC capillary commercially availablePPY Coated CapillaryPPY Coated CapillarySolSol--gel Coated Capillarygel Coated Capillary
Capillary packed with stainless steel wire Capillary packed with stainless steel wire or fiber /PEEKor fiber /PEEK tubetubeParticle packed capillary /PEEKParticle packed capillary /PEEK tube (MIP, tube (MIP, AlkylAlkyl--diol silica)diol silica)
C18 silica monolithic capillaryC18 silica monolithic capillary
Polymer monolithic capillaryPolymer monolithic capillary
Coated capillaryCoated capillary
Packing materialsPacking materials
Monolithic materialsMonolithic materials
◆ Sol-gel CME, as a viable solventless or little solvent extraction technique, was first introduced in 2002 by Bigham and workers. More and more papers was published in different scientific journals in recent years
◆Most applications of CME were focused on the organic analysis, very few reports on its application in inorganic analysis
Extraction Mode
1.Cap;2.Vial;3.Sample; 4.PDMS stir bar;5.Stir
Text
Text
Text
Text
Direct Headspace
Stir bar sorptive extraction (SBSE) is derived from solid-phase microextraction (SPME), which was developed by Baltussen et al in 1999
The amount of sorbent in the stir bar is higher than the amount in the SPME fiber, so better reproducibility and higher sensitivity and recoveryare expected
Stir Bar Sorptive Extraction
Microextraction Techniques Combined with Atomic
Spectrometry for Trace/ultratrace Elements Analysis in Environmental Water
MALDI-TOFMSESI-MS (MS)
ICP-IDMS
Microextraction Techniques
Combined with Electrothermal
Vaporization-ICP-MS for
Trace/ultratrace Elements Analysis
Electrothermal Vaporization (ETV)One of the versatile sample introduction techniques currently employed in plasma optical emission spectrometry and mass spectrometry.
low sample consumption (μL or mg)high transport efficiency (~80%)low absolute detection limit (fg)the ability to directly analyze both liquid and solid samples.
◆ High sensitivity◆ Good precision◆ Simultaneous multielemental analysis◆ Isotopic information◆ A dynamic range exceeding five orders of magnitude
The Features of ICP-MS for Elemental Analysis
The ways to improve the analytical performance of ETV-ICP-MS
◆ The best set-up of ETV device
◆ The employment of chemical modifier
◆ Combined with separation /preconcentration techniques
Microextraction: miniaturized sample pretreatment technique
LPME/CME/SBSE-ETV-ICP-MS----a perfect coupling for inorganic analysis
ETV: micro amount sample introduction technique
System for Single Drop Microextraction
Single drop microextraction (SDME)-ETV-ICP-MS for the determination of Be, Co, Pd, and Cd
L. B. Xia, B. Hu, Z. C. Jiang, Y. L. Wu, Y. Liang, Anal. Chem., 76(2004)2910-2915.
Benzoylacetone (BZA)
can chelate with Be, Co,
Pd, and Cd to form
thermally stable and
volatile complexes.
BZA was used both as
the extractant and
chemical modifier.
SDME parametersAqueous volume, 1 mL; benzene drop volume, 4 μL; extraction time, 10 min; flow rate: 0.2 mL/min.
(A) 20 pg Be with 0.1 μmol BZA as chemical modifier vaporized at 900 oC. (A’) The residual signal of empty firing at 2500 oC.(B) 20 pg Co with 0.1 μmol BZA as chemical modifier vaporized at 900 oC.(B’) The residual signal of empty firing at 2500 oC.
ETV signal profiles
Analytical performance
Analytical applications
ICP-AESICP-MS
MALDI-TOFMSESI-MS (MS)
ICP-IDMS
Speciation of Inorganic Selenium
L. B. Xia, B. Hu, J. Anal. At. Spectrom., 21(2006)362-365.
Extraction:Extractant, ammonium pyrrolidine dithiocarbamate (APDC)/CCl4;aqueous volume, 2.5 mL; pH, 5.0; stirring, 800 rpm; extraction time, 20 min.
Basis: The Se(IV)-PDC chelate could be extracted by CCl4 under the pH range of 4-6.2, and Se(VI) remains in aqueous phase. The sum of selenite and selenate was determined after prereduction of selenate to selenite by gentle boiling in 5 M HCl mediums for 50 min
The schematic of experimental set-up for HF-LPME
Hollow fiber liquid phase microextraction (HF-LPME)-ETV-ICP-MS for trace analysis
CE –HPLC –
GC –
ICP-AESICP-MS
ICP-IDMS
Analytical performance of two modes of LPME
Species Detection limit Actual enrichment factor RSD (%)
Instrument(ng/mL)
Methoda
(pg/mL)Methodb
(pg/mL) Methoda Methodb Methoda Methodb
Selenite 0.20 0.50 2.7 410 75 7.1 13.2
Selenate 0.23 0.56 3.0 410 75 7.6 13.9
(a) HF-LPME-ETV-ICP-MS. (b) SDME-ETV-ICP-MS.
Sample Selenite +Selenate Selenite Selenate Total Se by
PN-ICP-MS
East lake water 1.35±0.09 1.12±0.08 0.23±0.03 1.39±0.03
Pool water 0.90±0.07 0.79±0.05 0.11±0.02 0.92±0.03
Yangtze river water 0.70±0.08 0.62±0.06 0.08±0.01 0.72±0.03
Analytical results (mean±s d, n=3) for selenite and selenate in real water samples (ng/mL)
Sample
Speciation of Vanadium
CDTAMasking V(IV)
APDC HF-LPME
ETV-ICP-OESV(V)
APDC
HF-LPME
ETV-ICP-OES
Total V
V(IV)=Total V-V(V)
L. Li, B. Hu, L. B. Xia, Z. C. Jiang, Talanta, 70(2007)468-473.
HF-LPME Setup
200 400 600 800 1000 1200 1400 1600 1800 200010
15
20
25
30
35
40
45
1700 oC
Si
gnal
inte
nsity
(pea
k he
ight
)
Temperature (oC)
Effect of Vaporization Temperature
0 200 400 600 800 1000 1200
20
40
60
80
100
270 OC
Wei
ght %
Temperature/ OC
TG Curve of V-APDC Chelate
APDC Chemical Modification
Signal profileETV parameters
Drying: 100oC,ramp 10s, hold 15s
Vaporization: 1700oC, hold 6s
Cleaning: 2500oC, hold 3s
HF-LPME Conditions
2 3 4 5 60
10
20
30
40
50
Sign
al in
tens
ity (p
eak
heig
ht)
pH of sample
V-APDC V(IV)-CDTA
Solvent: CCl4
pH: 5.0Extraction time: 8 min APDC: 6.0×10-3 mol/L CDTA: 5.0×10-5 mol/L
LOD: 86 pg/mL for V(IV); 71 pg/mL for V(V)RSD: 5.3% (C=2.0 ng/mL, n=7)Enrichment factor: 74Linear range: 0.75~75 ng/mL, r2>0.99
Merits of Figures
Environmental WatersVanadium (IV) Vanadium (V)
Sample Added (ng mL-1)
Found (ng mL-1)
Recovery (%)
Added (ng mL-1)
Found (ng mL-1)
Recovery (%)
0 N.D. a 0 4.20 ± 0.26 3.96 ± 0.11 b
Lake water
5 5.15 ± 0.23 103 5 8.93 ± 0.46 98
0 N.D. a 0 2.41 ± 0.19 2.27 ± 0.13 b
Tap water
5 4.93 ± 0.18 99 5 7.52 ± 0.40 103
0 N.D. a 0 2.80 ± 0.11 Sea water
5 4.71 ± 0.22 94 5 8.35 ± 0.56 107
a not detected. b total concentration of vanadium determined by ICP-MS.
Ref. Analytes/Sample
FeaturesExtraction Analytical Performance
1 Cd, Pb/Fresh water, human serum
8-Hydroxyquinoline/Chloroform SDME
LOD(pg mL-1): Cd 4.6, Pb 2.9; EF: Cd 140, Pb 190
2 Al species/natural waters and
drinks
8-Hydroxyquinoline/chloroform SDME
LOD(pg mL-1): Al 3.3; EF: 210
3 Co, Hg, Pb/Lake water, serum,
hair
PAN/ [C4MIM][PF6] SDME
LOD(pg mL-1): Co 5.5, Hg 6.4, Pb 11.3; EF: Co 350, Hg 50, Pb
60
4 La PMBP/benzene SDME LOD(pg mL-1): La 16; EF: 500
5 Cu, Zn, Pd, Cd, Hg, Pb, Bi/Peach leaves
sea water
DDTC/CCl4 HF-LPME LOD(pg mL-1): 1.6(Bi)-28.7(Zn); EF: 20(Hg)-305(Cu)
LPME-ETV-ICP-OES/MS for Trace Analysis. A Survey
1. L. Li, B. Hu, L. B. Xia, Z. C. Jiang, Talanta, 70(2007)468-473.2. L. B. Xia, B. Hu, Z. C. Jiang, Y. L. Wu, L. Li, R. Chen, J. Anal. At. Spectrom., 20(2005)441-446.3. L. B. Xia, X. Li, Y. L. Wu, B. Hu, R. Chen, Spectrochim. Acta, 63B(2008)1290-1296.4. 吴英亮,江祖成,胡斌,高等学校化学学报,24(2003)1793-1794. 5. L. B. Xia, Y. L. Wu, B. Hu, J. Mass Spectrom., 42(2007)803-810.
CE –HPLC –
GC –
ICP-AESICP-MS
MALDI-TOFMSESI-MS (MS)
ICP-IDMS
(i) The method provided much larger enrichment factor and thus a much lower detection limit
(ii) Chelating reagent could be used both as extracting reagent and as chemical modifier, and analytes could be vaporized and transported as gaseous chelates into the ICP, therefore, improved the analytical sensitivity
(iii) LPME technique combined with a micro-amount detection technique was proved to be a perfect coupling and 100% of sample after pretreatment could be introduced into the ICP for detection
Summary
CE –HPLC –
GC –
ICP-AESICP-MS
MALDI-TOFMSESI-MS (MS)
ICP-IDMS
LPME Combined with GFAAS for trace Elements Analysis
Similar to ETV-ICP-MS, LPME is also very suitable for combination with GFAAS for trace elements and their speciation by selection of appropriate extraction system
Ref. Analytes/Sample
FeaturesExtraction Analytical Performance
1 Cd, Pb/ Environmental
water
dithizone/toluene SDME LOD(pg mL-1): Cd 2.0, Pb 90; EF: Cd 118, Pb 90
2 As(III), As(V)/Environmental
waters and human hair extracts
APDC/toluene HF-LPME LOD(pg mL-1): As 120; EF: 78
3 MeHg+/Hair extracts, sludges
toluene/thiourea HF-LLLME
LOD(pg mL-1): MeHg+ 100, EF: 204
4 Co, Ni/Environmental
water, rice
PAN/CCl4-acetone DLPME
LOD(pg mL-1):Co 21, Ni 33; EF: Co 101; Ni 200
LPME-GFAAS for Trace Analysis. A Survey
1. H. M. Jiang, B. Hu, Microchim. Acta, 2008, in press.2. H. M. Jiang, B. Hu, B. B. Chen, Anal. Chim. Acta, accepted.3. H. M. Jiang, B. Hu, B. B. Chen, W. Q. Zu, Spectrochim. Acta, 63B(2008)770-776.4. H. M. Jiang, B. Hu, B. B. Chen, W. Q. Zu, Spectrochim. Acta, 63B(2008)770-776.
6 μm silica skeletons
8 μm
25 nm
LOD:1.6 ng L-1
Preconcentration factor:436RSD:6.2% Simple, rapid, sensitive, high tolerance for the interference
Monolithic Capillary Microextraction-ETV-ICP-MS for Al Speciation
Fei Zheng, Bin Hu, Spectrochim. Acta Part B, 63(2008)9-18.
Analytical results of Al fractionation (mean ± s.d., n = 3) in rainwater and fruit juice
Sample pH aAlT / μg L-1 All / μg L-1 Alo / μg L-1bAll fraction
(%)
Rainwater1
Rainwater2
Rainwater3
Tomato juice
Cucumber juice
Watermelon juice
5.46
5.38
5.62
4.24
5.21
5.33
3.23 ± 0.15
2.94 ± 0.20
3.76 ± 0.18
6.21 ± 0.21
18.56 ± 0.74
33.29 ± 1.77
2.60 ± 0.08
2.01 ± 0.08
3.27 ± 0.16
4.71 ± 0.13
12.89 ± 0.84
15.33 ± 0.78
0.63 ± 0.02
0.93 ± 0.04
0.49 ± 0.03
1.50 ± 0.07
5.67 ± 0.38
17.96 ± 0.89
80.5 ± 2.5
68.4 ± 2.7
87.0 ± 4.3
75.8 ± 2.1
69.5 ± 4.5
46.0 ± 2.3
a All : labile monomeric Al; Alo: non-labile monomeric Al; AlT: total monomeric Alb The percentage of labile monomeric Al in total monomeric Al of real samples
Sample introduction system from the graphite adsorption bar to the ETV and the ETV-ICPconnecting interface
Graphite bar micro-extraction device
Zirconia-coated graphite adsorption bar
Xuli Pu, Bin Hu*, et al., J. Mass Spectrom., 41(2006)887-893.
Sample introduction system from the graphite adsorption bar to the ETV and the ETV-ICPconnecting interface
Analytical performance
Analytical application
ICP-AESICP-MS
MALDI-TOFMSESI-MS (MS)
ICP-IDMS
Capillary Microextraction on-line Hyphenated with ICP-MS for Trace
Elements Analysis
Simultaneous speciation of inorganic As(III)/As(V) and Cr(III)/Cr(VI) in natural waters utilizing ordered mesoporous Al2O3 CME-ICP-MS
Wenling Hu, Fei Zheng, Bin Hu, et al., J. Hazedous. Mater., 151(2008)58-64.
Sample loading
Elution/eluent introduction
Scanning electron microscopic images of (A) enlarged surface view of hostile capillary, (B) enlarged surface view of ordered mesoporous Al2O3coated capillary.
A B
TEM micrographes of (C) ordered mesoporous Al2O3coating, magnification: 50,000 ×(D) non-mesoporous Al2O3 coating,magnification: 30,000 ×
C D
Effect of pH on the adsorption rate (%) of As(V), As(III), Cr(VI) and Cr(III)
Capillary: 40 cm × 320 µm i.d.Separation pH: pH 4.0Sample flow rate: 0.1 mL min-1
Eluent: 0.1 mL of 0.01mol l-1 NaOH at flow rate of 0.1 mL min-1
Separation conditions
Detection limits : 0.7 and 18 ng L-1 for As(V) and Cr(VI), and 3.4 and 74 ng L-1 for As(III) and Cr(III)
Enrichment factor: 5
RSDs: 3.1, 4.0, 2.8 and 3.9 % (C= 1 ng mL−1, n = 7) for As(V), As(III), Cr(VI) and Cr(III).
SEM for MPTS-silica monolithic capillary
SEM for AAPTS-silica monolithic capillary
600× 2400×
On-line dual silica monolithic CME-ICP-MS for sequential determination of inorganic arsenic and selenium species
1 2 3 4 5 6 7 8 90
20
40
60
80
100
Abso
rptio
n pe
rcen
tage
(%)
pH
As(III) Se(IV) As(V) Se(VI)
0 1 2 3 4 5 6 7 8 9 100
20
40
60
80
100
Adso
rptio
n pe
rcen
tage
(%)
pH
As(V) Se(VI) As(III) Se(IV)
Effect of pH
3-mercaptopropyltrimethoxysilane (MPTS)
AAPTS
Fei Zheng, Bin Hu, J. Anal. At. Spectrom., submitted. N-(2-aminoethyl)-3-aminopropyltrimethoxysilane
(AAPTS)
MPTS-silica monolithic capillary (-SH)As(III)/Se(IV) retained was eluted with 100 μL of 0.2 mol L-1 HNO3-3% thiourea (m/v)
AAPTS-silica monolithic capillary (-NH2)As(V)/Se(VI) retained was eluted with 100 μL of 0.5 mol L-1 HNO3
On-line dual silica monolithic CME-ICP-MS
SpeciesLinear range
(µg L-1)Linear equations
Linear coefficient
(R2)
R.S.D(C=1 μg L-1,
n=7)
Detectionlimits
(ng L-1)
Enrichmentfactor
As(III)Se(IV)As(V)Se(VI)
0.05-160.1-160.05-160.05-16
y = 80130x-2993y = 13706x-2759y = 84416x+422y = 14246x+5975
0.99830.99470.99780.9924
4.3%3.3%5.8%6.5%
10.931.16.211.6
34.337.536.139.0
Analytical performance of on-line dual-column CME-ICP-MS
Samples Element Certified(μg L-1)
Determined(μg L-1)
t-Testc
GSB Z50004-88
GBS Z50027-94
Total AsAs(III)As(V)
Total SeSe(IV)Se(VI)
59.3 ± 4.2--
23.8 ± 2.7--
54.0 ± 5.4a
3.4 ± 0.250.6 ± 5.225.3 ± 1.4b
3.3 ± 0.122.0 ± 1.4
1.701.86
a This total As is the sum of As(III) and As(V) determined through on-line dual silica monolithic CME-ICP-MS system; b This total Se is the sum of Se(IV) and Se(VI) determined through on-line dual silica monolithic CME-ICP-MS system; c t0.05,2 = 4.30
Analytical results of As(V), As(III), Se(IV) and Se(VI) in CRM environmental water (mean ± s.d., n=3)
CE –HPLC –
GC –
ICP-AESICP-MS
MALDI-TOFMSESI-MS (MS)
ICP-IDMS
Microextraction Combined with
Chromatographic Techniques
for Environmental Water
Analysis
CE –HPLC –
GC –
ICP-AESICP-MS
MALDI-TOFMSESI-MS (MS)
ICP-IDMS
Determination of organophosphorus pesticide residues using SDME-GC-FPD
Q. Xiao, B. Hu, Talanta, 41(2006)887-893.
The factors affecting the extraction efficiencyOrganic drop volume: 1.5 µL toluene Extraction time: 20 minStirring rate: 600 rpm Sample pH: pH 5-6 (natural pH for waters)Salt concentration: No salt addition Extraction temperature: Room temperature
Analytes A B R2 Enrichment factors
LODs(ng/ml)
dichlorvos -0.02824 0.10859 0.99949 23 0.58phorate -0.04029 0.40819 0.99993 97 0.22fenitrothion 0.00332 0.45375 0.99984 109 0.35malathion 0.03596 0.30824 0.99967 99 0.26parathion 0.02198 0.39791 0.99976 99 0.21quinalphos 0.02985 0.35295 0.99953 97 0.37
Analytical Performance
OPPs Added/ng·ml-1
Found/ ng·ml-1
Recovery/% RSD/%
dichlorvos 25
1.974.62
98.692.4
0.72.4
phorate 25
1.815.32
90.7106.5
8.52.7
fenitrothion 25
1.814.94
90.898.9
5.43.3
malathion 25
1.824.89
91.497.7
4.62.7
parathion 25
1.834.84
91.796.9
6.12.7
quinalphos 25
1.914.97
95.599.4
6.80.6
Six OPPs recoveries in East Lake water samples
Fruit juice analysis: No OPPs was detected in pear juice, organge juice and apple juice. The recoveries for all spiked fruit juice samples(analysed after dilution) were between 77.7% and 113.6% with an RSD of less than 13.4.
HS-SDME Coupled with GC-ICP-MS for Butyltin Compounds Speciation
GC-ICP-MS
Schematic of experimental set-up of HS-SDME
4.0 4.5 5.0 5.5 6.0 6.5 7.0
0
250000
500000
750000
1000000
1250000
1500000
1750000
Sign
al in
tens
ity
Time (min)
STD solution
PACS-2 sediment
MBT
TPrT(I.S.)
DBT TBT
Chromatograms for sample
Q. Xiao, B. Hu, M. He, J. Chromatogr. A, 1211(2008)135-141.
NaBEt4derivatization HS-SDMESolvent: 2.0 µL decane; 0.5%NaBEt4: 20 µL; pH: 5; stirring: 600 rpm, 5 min
NaBH4derivatization HS-SDMESolvent: 2.0 µL decane; 3%NaBEt4: 0.2 mL; pH: 3; stirring: 600 rpm, 5 min
Analytical performance data by HS-SDME-GC-ICP-MS
Comparison of detection limits for butyltins
Analysis of butyltins in seawater sample ( n = 3)
Determination of butyltins in PACS-2 sediment (mean±s.d., n=3)
Analysis of butyltins in shellfish samples ( n = 3)
Chemical structures of PBDEs
HF-LPME-GC-ICP-MS for the Analysis of Polybrominated Diphenyl Ethers
Qin Xiao, Bin Hu, et al., J. Am. Soc. Mass Spectrom., 18(2007)1740-1748.
Microextraction conditionsExtraction solvent: decane 30% methanol was added to avoid the adsorption of apolar compounds on the glass walls Stirring rate: 1000 rpmExtraction time: 20 minExtraction temperature: 40 oCIon strength: no salt addition
Monitoring isotope79Br and 81Br
Analyte Enrichment factors of HF-LPME
BDE28 83
BDE47 54
BDE100 37.5
BDE99 30.5
Enrichment factors
AnalyteLinearity/
ng/mL R Detection Limit/ ng/L RSD/%
BDE28 0.2-20 0.9999 15.2 6.8BDE47 0.2-20 0.9999 32.8 5.1
BDE100 0.2-20 0.9999 24.5 9.1
BDE99 0.2-20 0.9990 40.5 8.3
Analytical performance
Real sampleSample
preparationaExtraction
timeDetection technique
Injection volume
LODs Ref.
human serum,water, soil, and
dust
HF-LPME 20 min GC-ICP-MS 1 μL 15.2-40.5 ng/L This work
sewage sludge LLE 18 h GC-ICP-MS 2 μL 90-200b ng/L [22]
water samples HF-MMLLE 60 min GC-MS 2 μL 0.3-1.1 ng/L [20]
water samples SBSE 25 h GC-MS - 0.3-7.8 ng/L [9]
food samples SPE-HPLC fractionation
- GC-MS-MS 4 μL 80-680 ng/L [30]
water samples HS-SPME 30 min GC-MS-MS - 0.02-0.06 ng/L [8]
solid samples HS-SPME 60 min GC-MS-MS - 5.4-109 pg/g [31-32]
sediments MAE 24 min GC-ITMS 70 μL 4-20 pg/g [33]
birds SPE - GC-MS - 0.1 and 0.4 ng/g [34]
a: HF-LPME, hollow fibre liquid phase microextraction; LLE, liquid liquid extraction; HF-MMLLE, hollow-fiber microporous membrane liquid–liquid extraction; SBSE, stir bar sorptive extraction; SPE, solid phase extraction; HS-SPME: headspace-solid phase microextraction; MAE, microwave-assisted extraction.b: instrument detection limits.
Comparison of the methods for the determination of PBDEs
COLLEGE OF CHEMISTRY AND MOLECULAR SCIENCES, WUHAN UNIV.
HF-LPME-GC-ICP-MS chromatograms for soil (a), dust (b), water (c) and serum (e)
• Soil, dust, water and serum
0 2 4 6 8 10 12
0
50000
100000
150000
200000
Sign
al in
tens
ity (C
PS)
Time (min)
BDE28
BDE47
BDE100
BDE99I. S.
abcdefg
a: Soilb: Dustc: East Lake waterd: East Lake water spiked 1 ng/mLe: Human serum (10-fold dilution)f: Human serum spiked 10 ng/mL (10-fold dilution)g: Human serum spiked 50 ng/mL (50-fold dilution)
HS-SDME-HPLC for Polycyclic Aromatic Hydrocarbons (PAHs)
HS-SDME conditions
Extraction solvent: 10 μL saturated β-cyclodextrin solution; pH: 5.0
Addition salt: 0.2 g/mL NaCl; Temperature: 40oC
Extraction time: 10 min; Stirring speed: 1000 rpm
Y. L. Wu, L. B. Xia, R. Chen, B. Hu, Talanta, 74(2008)470-477.
PAH Instrument(ng/mL)
Method(ng/mL)
Actualenrichment factor
RSD (%) DLR
nap 6.0 0.097 30 6.1 0.3-50
phe 3.8 0.016 53 7.1 0.05-5
ant 1.5 0.004 18 5.6 0.01-1.25flu 28.0 0.247 50 6.7 0.7-50Pyr 11.6 0.098 20 6.1 0.3-50
Analytical performance
Determination of PAHs in waters
Inclusion precedure
β-cyclodextrin
3 4 5 6 7 8 9 10 11 12
23
24
25
26
27
28
29
30pyr
flu
ant
phe
nap
fluor
esce
nce
inte
nsity
/LU
time/min
with ß-CD without ß-CD
•Extract PAHs effectively by forming inclusion complex•Enhance the fluorescence intensity in HPLC analysis
β-cyclodextrin
PAHs Added (ng/mL) Determined (ng/mL) Recovery (%)
NAP
0 0.71 -
2 2.88±0.05 108.5±5.1
5 5.68±0.17 99.4±8.1
10 10.83±0.09 101.2±2.1
PHE
0 0.38 -
0.2 0.57±0.01 95±5.1
0.5 0.89±0.02 102±6.5
1 1.35±0.04 97±8.5
ANT
0 0.08 -
0.05 0.127±0.002 94±4.7
0.125 0.217±0.006 109.6±8.0
0.25 0.332±0.008 100.8±6.9
FLU
0 n.d.a -
2 2.21±0.05 110.5±6.5
5 5.23±0.11 104.6±6.1
10 10.34±0.24 103.4±6.7
PYR
0 0.33 -
2 2.48±0.06 107.5±7.0
5 5.48±0.09 103±4.8
10 10.35±0.25 100.2±7.0
Analytical results of PAHs in real water sample (Mean±sd, n=3)
CE –HPLC –
GC –
ICP-AESICP-MS
MALDI-TOFMSESI-MS (MS)
ICP-IDMS
LLLME-HPLC-UV for Organomercury
CE –HPLC –
GC –
ICP-AESICP-MS
MALDI-TOFMSESI-MS (MS)
ICP-IDMSSpecies LOD Actual enrichment factor (fold)
RSD (%) method (n=7)
Equation Correlation coefficient
Linearity (ng mL-1)
Instrument (µg mL-1)
Method (ng mL-1)
MeHg 0.45 3.8 120 8.9 y=0.9+0.05857x 0.9920 5-100
EtHg 0.15 0.7 215 6.4 y=0.6+0.155x 0.9862 1-100
PhHg 0.10 0.29 350 6.6 y=-3.7+0.39143x 0.9976 1-100
Analytical performance for the analysis of organomercury by LLLME-HPLC
LLLME-HPLC-UV for Organomercury
L. B. Xia, Y. L. Wu, B. Hu, J. Chromatogr. A, 1173(2007)44-51.
SampleSpecies
East lake water Synthetic water sample
Added (ng/mL)
5 10 20 5 10 20
Determined MeHg 5.92±0.56 10.88±1.02 20.86±1.33 4.90±0.52 10.11±0.88 20.09±1.22
EtHg 4.98±0.43 10.09±0.65 19.88±1.07 5.03±0.49 9.92±0.54 20.13±0.98
PhHg 5.02±0.43 9.97±0.63 19.90±1.01 4.98±0.45 9.97±0.55 19.88±1.03
Analytical results of water samples (mean±sd, n=3)
CE –HPLC –
GC –
ICP-AESICP-MS MALDI-TOFMS
ESI-MS (MS)
ICP-IDMS
Methylmercury (as Hg) in DORM-2 was found to be 4.42±0.41 μg g−1, which was in good agreement with the certified value (4.47± 0.32 μg g−1) for methylmercury.
Certified reference material
Standard mixture
HPLC mobile phase, 70% methanol, 30% 0.02M NaAc-Ac, (PH6.0, containing 0.1 mM 2-mercaptoethanol), 0.01M Na2S2O3
Organic solvent:Toluene
Stirring speed: 1500 rpm
Extraction time: 20 min
Acceptor:0.05M Na2S2O3
LLLME parameters
Headspace single drop and hollow fiber liquid phase microextractions for HPLC determination of phenols
HS-SDMEDonor phase: 0.05 mol L-1 HNO3 Acceptor phase: 0.05 mol L-1 NaOHMicrodrop volume: 10 µL Sample-to-headspace volume ratio: 3:1Extraction temperature: 70 oCStirring rate: 1000 rpmExtraction time: 15 minSalt addition: 0.25 g mL-1 NaCl
HS-HF-LPMEDonor phase: 0.05 mol L-1 HNO3 Acceptor phase: 0.05 mol L-1 NaOHMicrodrop volume: 10 µL Sample-to-headspace volume ratio: 1:1Extraction temperature: 60 oCStirring rate: 900 rpmExtraction time: 20 minSalt addition: 0.25 g mL-1 NaCl
Experimental set-up for HS-HF-LPME
Y. L. Wu, B. Hu, Y. L. Hou, J. Sep. Sci., published online.
Analytical performance data for phenols
Analytes Linearity range
Correlationcoefficient
(r2)
Limits of detection
(LODs, ng mL-1)
Enrichment factor
RSD (%)(n=7)
HS-SDME
Ph 10-1000 0.9944 2.1 15.8 3.7
CP 1-500 0.9981 0.2 198.9 4.0
DCP 5-500 0.9979 0.8 159.7 9.8
TCP 5-500 0.9935 1.1 194.8 6.7
HS-HF-LPME
Ph 10-1000 0.9962 4.2 9.2 6.3
CP 5-500 0.9980 0.4 149.9 3.6
DCP 5-500 0.9989 0.4 301.9 3.1
TCP 5-500 0.9996 0.4 411.1 4.8
Honey and three real environmental water samples including East Lake water, Yangtz River water, and tap water were analyzed and no target analytes in honey and all the three water samples were detected. The content of phenol (Ph) in toner obtained by HS-SDME-HPLC-UV and HS-HF-LPME- HPLC-UV was found to be 2.92 ±0.19 and 2.76 ± 0.24 µg g -1, respectively.
Chromatograms of HS-HF-LPME-HPLC-UV and HS-SDME-HPLC-UV for the toner sample and spiked toner sample
Ph
CP
DCPTCP
HS-HF-LPME-HPLC-UV for toner
HS-SDME-HPLC-UV for toner
HS-HF-LPME-HPLC-UV for spiked toner
HS-SDME-HPLC-UV for spiked toner
◆ Since there was no direct contact with the sample matrix, both HS-SDME and HS-HF-LPME were performed without interference.
◆ HS-SDME is simpler than HS-HF- LPME, while HS-HF-LPME is more robust than HS-SDME and can tolerate a relatively higher stirring rate.
◆ Compared to HS-SDME, HS-HF-LPME has larger specific extraction interface that makes the volatile compounds especially the less volatile compounds reach the equilibrium in a short time.
◆ Either HS-SDME or HS-HF-LPME combined with HPLC-UV has been demonstrated to be an effective method for the analysis phenols in real world samples with different matrix.
Summary
CE –HPLC –
GC –
ICP-AESICP-MS
MALDI-TOFMSESI-MS (MS)
ICP-IDMS
(i) Three microextraction techniques, LPME, CME and SBSE, are faster, simpler, inexpensive and more environmentally friendlysample-preparation techniques;
(ii) The device of LPME is quite simple, and no sample carry-overassociated with it, but its reproducibility should be improved;
(iii) The volume and surface area of the extraction phase for SBSE are larger than those of CME, thus, a better reproducibility and higher sensitivity than CME are expected when SBSE is used.
(iv) Compared with LPME, SBSE is more robust;(v) Several unsolved problems associated with CME and SBSE,
such as the physical damage of the coating, limited SBSE coatings available;
(vi) Microextraction techniques combined with different detection methods are simple and robust, suitable for the implementation of trace metals (including speciation) and organic pollutants analysis in routine protocols for environmental water.
Conclusions
Acknowledgments
◆ National Nature Science Foundation of China
◆ Excellent Young Scientist Foundation of Hubei Province
◆ NCET, MOE of China
◆ Wuhan Municipal Science & Technology Committee
Thank you for your attention!