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Uppsala University
Bachelor project 15hp
Vt15
Determination of trace and major elements in oil by
ICP-AES after microwave digestion
Amalia Lundholm
Supervisor: Jean Pettersson
2
Table of content Abbreviations .......................................................................................................................................... 2
Introduction ............................................................................................................................................. 3
Material and method .............................................................................................................................. 4
Chemicals and glassware ..................................................................................................................... 4
Apparatus ............................................................................................................................................ 4
Calibration curves ................................................................................................................................ 4
Samples and sample preparation ........................................................................................................ 4
ICP-AES measurements ....................................................................................................................... 6
Method validation ............................................................................................................................... 6
Results and discussion ............................................................................................................................. 7
Standard oils ........................................................................................................................................ 7
Lignin oils ............................................................................................................................................. 8
Conclusion and further testing .......................................................................................................... 14
References ............................................................................................................................................. 15
Appendix ................................................................................................................................................ 16
Standard oils ...................................................................................................................................... 16
Lignin oils ........................................................................................................................................... 18
Abbreviations ICP-AES Inductively coupled plasma atomic emission spectroscopy
JL JL166DV, liquid lignin oil
BO 161 botton, liquid lignin oil
RF RAFAP 2e91, solid lignin oil
STDAV Standard deviation
RSD Relative standard deviation
LOQ Limit of quantification
3
Introduction A company called RenFuel got its laboratories at BMC, Uppsala University. Their business plan is to
convert lignin, which is a by-product in the forest industry, into a biochemical oil that later can be used
as fuel to reduce our dependence on fossil fuel. (RenFuel, 24-05-2015) RenFuel sends their oils for
analysis to the analytical chemistry department at Uppsala University, to measure trace and major
elements in the lignin oils.
Lignin can be found in plant cell walls, as the essential glue between the cellulose microfibrilis. Lignin
is a large aromatic polymer that makes up 15-30% of the plants weight. The paper industry produces
large amount of lignin, but most of it are not being used for anything, but is burned as low value fuel.
(Zakzeski, Bruijnincx, Jongerius, & Weckhuysen, 2010)
Lignin oil or LIGNOL® is produced at atmospheric pressure, below the boiling point with low use of
energy, 1 ton lignin becomes 1 m3 oil. This is made by a catalytic process on the lignin that takes a
couple of hours. (Zakzeski, Bruijnincx, Jongerius, & Weckhuysen, 2010)
The method of analysing Lignin oil currently being used at Uppsala University are open vessel digestion
followed by inductively coupled plasma atomic emission spectroscopy (ICP-AES). Quantitative
measurements of various different elements can be made with sufficient accuracy, but the method is
considered to be too slow. This is because of the open vessel digestion, which takes approximately
four days.
The reason why oil need to be digested prior to analysing it with ICP-AES are so that the large organic
compounds wont clog up the system, also, the sample need to be water soluble for the ICP-
measurements. (Harris, 2010)
Open vessel digestion uses acid and heat to break down the oil, which can take time since the oil isn’t
soluble in the water soluble reagents, and therefore have a small reaction surface. Furthermore, the
temperature can’t be too high since this would lead to losses of the volatile elements, also, the
temperature need to be below the boiling point of the reagents. Microwave digestion can be used as
a closed system, and can therefore use both temperature and pressure to break down the oil. Since
the system is closed there are less risk of contamination and losses of volatile product, which means
that the temperatures can be higher than in an open system, and that the pressure can be varied also
speeds up the digestion process. (Harris, 2010)
Microwave digestion were suggested as a replacement for the open vessel digestion, and several
articles describing the method of microwave digestion to make oil samples ready for ICP-AES analysis
have been published, and the ones that are closest to this project studied different kinds of edible oils.
In one study the authors had determined trace elements in pumpkin oil, and were successful in
detecting Ca, Cd, Co, Cr, Cu, Fe, K, Mg, Mn, Mo, Na, Ni, Pb, Ti, V and Zn, but could not measure Al, Cr,
P, since limit of detection was too high and the concentrations too low. The recoveries for all elements
were >95% with exception for S, that only had a recovery of <50%. They used nitric acid and hydrogen
peroxide for the microwave digestion. (Juranovic, Breinhoelder, & Steffan, 2003)
Other articles that have given good results with the microwave digestion are a study to determine
trace elements in olive oil (Zeinera, Steffana, & Cindric, 2005), a quantitative study on metals in virgin
olive oil (Llorent-Martı´nez, Co´rdova, Ortega-Barrales, & Ruiz-Medina, 2014) and analysis of nickel in
cottonseed oil. (Menga & Zhang, 2011) All of these mentioned articles use nitric acid and hydrogen
peroxide for the digestion.
4
The theory where that microwave digestion could be used as a replacement for the open vessel
digestion, and after searching after articles on the subject of oil analysis this seemed to be a valid guess.
The purpose of this project where to optimize and validate a method to determine trace and major
elements in Lignin oil using microwave digestion to break down the oil and make it water soluble, and
then make quantitative measurements of the elements using ICP-AES.
Material and method
Chemicals and glassware The chemicals being used during this project where nitric acid (HNO3, 65%) and hydrogen peroxide
(H2O2, 30%). The nitric acid where sub-boiled before being used, to remove traces of metals.
Two different oil analysis standards were used for method validation, CONSTAN Sulphur (0,5% Wt.)
and CONSTAN S-21+K (300 ppm Wt.), a multi-element oil containing Au, Al, B, Ba, Ca, Cd, Cr, Cu, Fe, K,
Mg, Mn, Mo, Na, Ni, P, Pb, Si, Sn, Ti, V and Zn.
To calibrate the ICP-AES calibration solutions were prepared from a multi-element standard solution
(5% HNO3) containing 10 ppm of As, B, Ba, Cd, Co, K, Li, Mg, Mn, Mo, Na, P, Rb, Sr, Ti, V and Y, and 9.7
ppm of Ag, Al, Bi, Ca, Cr, Cu, Fe, Ni, Pb, S, Se, Zn.
Glassware used during the open vessel digestion were volumetric flasks made of quartz glass.
All standards and samples were diluted with Milli-Q water in sterile Polypropylene Conical Falcon
tubes.
Apparatus The ICP-AES used was a SPECTRO CIROSCCD whit a Modified Lichte nebulizer spraychamber and
SPECTRO Smart Analyzer Vision Software.
The microwave digestion was done using a Titan MPSTM 16 position microwave sample preparation
system, with 75mL (40 Bar) TFM digestion vessels.
During the open vessel digestion the samples were heated with a programmable EUROTHERM heater
in an aluminium block.
Calibration curves The ICP regression lines for the different elements were calculated by the smart analyser program from
measurements on standard solutions. Three solutions were prepared from a multi element standard
and diluted with nitric acid and Milli-Q water to 0, 1 and 5 ppm. The amount of nitric acid varied
depending on the acid concentration in the digested and diluted samples. The ICP were recalibrated
with new standard solutions before each set of measurements.
Samples and sample preparation During this project three different Lignin oils have been studied, and in table 1 follows a short
description of the samples.
Table 1: Description of lignin oil samples.
Sample name Abbreviation State Comment
JL166DV JL Liquid Viscous, difficult to work whit
161 Botton BO Liquid More fluid than JL, not as thick and viscous
RFAP 2e91 RF Solid Solid, but soft, pieces could be removed whit spatula
5
Open vessel digestion
The Glassware used during the open vessel digestion where thoroughly rinsed with Milli-Q water and
nitric acid. Before adding the samples and reagents the glassware where dried in an oven set to 80°C
and then cooled at room temperature.
Approximately 0.2000g of the oils where weighed directly into volumetric flasks. 4.00mL HNO3 and
2.00ml H2O2 where added to each sample, and at the same time two blanks were prepared with the
same amount of HNO3 and H2O2.
The samples got two hours to react in room temperature, then the temperature was raised to 80°C for
a couple of hours. The samples were left over night at 105°C, and then raised again to 150°C. The
solutions were monitored during the days, and if they started to boil to much the flasks were removed
from the aluminium block to cool, and then slowly heated to 150°C again.
The oils were completely digested after approximately four days, but more often than not the samples
were left at 150°C over the weekend, and then found to be digested on Monday, so it is difficult to say
how long time it actually took. The solutions were transferred to 14ml Falcon tubes quantitative, which
means that the flasks were rinsed with an amount Milli-Q water three times, so that more of the oil
could be transferred to the tubes. Finally the oils were diluted with Milli-Q water to 14ml.
After measurements with the ICP, some of the oils were diluted further, because that the sulphur
concentrations were too high, and therefore not in the linear range. 500µl of the sample were
transferred to a 14ml Falcon tube, 5ml HNO3 was added and the solution was diluted with Milli-Q
water.
Microwave digestion
Before using the Tritan MPSTM the digestion vessels had to be cleaned properly, this was done by filling
the vessels with 5ml HNO3 and 3ml H2O2, which is the amount of reagents later being used for digesting
the samples, and then running the temperature program described in table 2. After the program was
done, the vessels were left in the microwave for 20 minutes, so they wouldn’t be too hot. Finally, the
vessels were rinsed with Milli-Q water before adding the samples.
The digestion vessels for the microwave digestion were quite large, 1kg each, and were therefore too
heavy for the analytical scale, so the oils could not be weighed directly into the vessels. Several
different ways of deciding the exact amount of oil were tried. Two methods were most efficient for
the liquid oils, the first were some of the oil was transferred to a plastic, one use only, container, the
oil was weighted and then poured into the vessel, the container was then weighted again to see how
much of the oil that had stuck to the walls, this was subtracted from the result. The other method was
to drop the oil on a filter paper, the filter paper could be weighted at the same time as the oil was
added, which gave more control over how much sample that was put into the digestion vessels.
Approximately 0.2400g of oil was used for each sample. An oil-free paper was added to the blanks.
Then 5ml HNO3 and 3ml H2O2 were added to the oils, and three blanks were prepared using 5ml HNO3
and 3ml H2O2. The vessels were left open for 10-15min before being closed and put into the microwave.
The microwave was programed with the temperature program found in table 2.
After the digestion all samples were transferred to 14ml Falcon tubes and diluted with Milli-Q water
the same way as described for the open vessel digestion. Some of these samples also had a too high
sulphur concentration, and was diluted further for more measurements.
6
Table 2: Temperature program, microwave digestion
Step Temperature [°C] Pressure [bar] Ramp time [min] Hold time [min] Power [%]
1 170 40 2 5 60
2 190 40 2 10 80
3 210 40 2 15 100
4 50 40 1 10 0
The temperature program was found in the reference notebook of microwave applications, belonging
to the microwave. The pressures was however altered, they had to be reduced since the temperature
program was originally made for the 100ml digestion vessels, not the 75ml that was used during this
project.
ICP-AES measurements Table 3 shows the ICP-AES settings.
Table 3: ICP-AES settings
Coolant Flow 14L/min
Auxiliary Flow 0.9L/min
Nebulizer Flow 0.9l/min
Pump Flow Rate 2.5ml/min
It took approximately three minutes to measure one sample, and that includes preflush. The ICP
measures three times on each sample, before calculating a mean value. The RSD-values for the ICP are,
however, not discussed in this report.
In the SPECTRO Smart Analyzer Vision Software recommended wavelengths for measurements on the
different elements can be found, most elements have been measured with two different wavelengths.
In the results, however, are only one presented. The one that has been selected is less interfered by
other elements, or is proven better at detecting low concentrations.
Method validation In order to analyse the methods ability to give correct values measurements were made on standard
oils with a known concentration of different elements. The open vessel digestion as well as the
microwave digestion was done as described in the sample preparation, but the oils wasn’t weighted
on filter papers for the microwave digestion, instead, the first method was used, where a tube
containing the oil were weighted before and after.
From the data obtained the standard deviation, STDAV, as well as the relative standard deviation, RSD,
could be calculated for each element and method respectively, so that the methods could be
compared. LOQ, limit of quantification, was calculated from the measurements on the blanks as seen
in eq1, and made it easier to see if the measured element concentrations could be distinguished from
the blanks.
𝐿𝑂𝑄 = 3 × 𝑆𝑇𝐷𝐴𝑉(𝑏𝑙𝑎𝑛𝑘𝑠) × 3.3 (𝑒𝑞1)
7
Results and discussion
Standard oils In table 4 below are the results from the ICP-AES measurements made on the multi-element standard
oil. Two replicate samples was made with the open vessel digestion and three replicate samples was
made with the microwave digestion, table 3 shows the mean value of the calculated concentrations.
In appendix A1 the original measurements for all the replicates are presented, before they were
recalculated with regard to the dilution and weight of the oil sample. The recalculated values can be
found in appendix A2.
Table 4: Mean values of ICP-AES measurements on multi-element oils (300ppm), using the two different digestion methods, microwave digestion (Micro) and open vessel digestion (Open).
Element Wavelength [nm]
Al 396.152
Ag 338.289
Ba 455.404
Ca 393.366
K 766.491
Mg 279.553
Mo 202.030
MV Micro [ppm] 276 302 298 325 189 333 304
MV Open [ppm] 289 326 326 341 210 346 288
Element Wavelength [nm]
Na 589.592
Ni 231.604
Pb 220.353
Zn 213.856
Cu 324.754
Fe 259.941
Cr 267.716
MV Micro [ppm] 228 323 313 290 322 318 309
MV Open [ppm] 245 344 328 322 330 273 314
Element Wavelength [nm]
B 208.959
Cd 214.438
Mn 257.611
P 177.495
Ti 334.941
V 292.464
MV Micro [ppm] 252 296 334 320 318 307
MV Open [ppm] 282 319 342 207 149 310
The result are also presented in the bar chart below, figure 1. The black line shows 300ppm.
Figure 1: Mean values of ICP-AES measurements on multi-element oils (300ppm), using the two different digestion methods, microwave digestion (Micro) and open vessel digestion (Open).
It seems that the microwave digestion gives good recovery for all elements except potassium and
sodium. Boron also seems to be a tricky element. The concentrations for the other elements only
deviates from 300ppm with a few %. The open vessel digestion have similar results compared to the
microwave digestion, except for phosphorus and titanium that gives low recoveries.
0
50
100
150
200
250
300
350
400
[pp
m]
Micro Open
8
The reason why sodium and potassium can be difficult to measure in oil often depends on that they
are easily ionized, which means that the ICP can’t decide the correct value. (Harris, 2010)
The measurements after microwave digestion was made on three samples, but the open vessel
digestion only had two. The results therefore have a degree of uncertainty, especially for the open
vessel digestion. By looking in appendix A2 one can see that the deviation between some of the
replicates are quite large, as for example Ba that in the first sample, M1, had a concentration of
326ppm, and a concentration of 384ppm for the second sample, M2.
But the overall trend appears to be that the open vessel digestion give slightly larger values than the
microwave digestion. The reason for this is difficult to say, it might be a coincidence, since some of the
values for the open vessel digestion differs so much for some elements. More tests are needed.
More measurements needs to be done to be sure, but it seems like the microwave digestion gives
better results, both in recovery, but also better standard deviation for the replicates.
The results from measurements on the standard oil with 5000ppm sulphur can be found in table 5
below. For the full data, se appendix A3 and A4.
Table 5: Mean values of ICP-AES measurements on standard oil with 5000ppm sulphur, using the two different digestion methods, microwave digestion (Micro) and open vessel digestion (Open).
Element Wavelength [nm]
S 182.034
Micro S [ppm] 5858
Open S [ppm] 6542
The results from this measurements are high, both for the microwave digestion and the open vessel
digestion. This probably depends on that it was difficult to get good regression lines for sulphur during
the ICP-calibration. But also here can a higher value for the open vessel digestion be seen.
Lignin oils Even for the samples, only elements present in the multi-element oil can be found in the results, i.e.
Au, Al, B, Ba, Ca, Cd, Cr, Cu, Fe, K, Mg, Mn, Mo, Na, Ni, P, Pb, Si, Sn, Ti, V and Zn.
In the following three tables 6, 7 and 8, ICP-results after the microwave digestion on the three lignin
oils can be found. Only elements that gave signals over the limit of quantification, LOQ, and therefore
was distinguishable from the blanks, are presented. The concentrations have been recalculated to take
account of the dilution and weight of the oil sample. For all the measurements, see appendix A5, A6
and A7.
9
Table 6: Oil JL166DV, microwave digestion on three replicates. Mean value (MV), standard deviation (STDEV) and relative standard deviation (RSD).
Element Wavelength [nm]
Mg 279.553
Zn 213.856
Cr 267.716
B 208.959
Cd 214.438
Micro JL1 [ppm] 0.131 0.113 0.050 0.925 0.029
Micro JL2 [ppm] 0.057 0.076 0.084 0.847 0.021
Micro JL3 [ppm] 0.040 0.167 0.060 0.681 0.028
MV JL [ppm] 0.076 0.119 0.065 0.818 0.026
STDEV [ppm] 0.05 0.05 0.02 0.12 0.004
RSD [%] 64 39 27 15 17
Element Wavelength [nm]
P 177.495
Ti 334.941
V 292.464
S 182.034
Micro JL1 [ppm] 8.13 0.139 0.014 834
Micro JL2 [ppm] 4.74 0.101 0.026 832
Micro JL3 [ppm] 5.71 0.133 -0.010 805
MV JL [ppm] 6.19 0.124 0.010 824
STDEV [ppm] 1.7 0.02 0.02 16
RSD [%] 28 16 183 1.9
For the JL166DV oil, only nine out of twenty elements gave a high enough concentration-signal to be
distinguished from the blanks, but the relative standard deviation is quite high for all the elements.
This is probably because the concentrations are quite low, which gives high uncertainty while
measuring with the ICP-AES.
Magnesium and vanadium have really high RSD-values, this is due to that the magnesium
concentration measured in JL1 is too high and the vanadium concentration measured in JL3 is too low,
relative the other replicates. They can probably be seen as outliners, but to be sure more
measurements needs to be made.
Table 7: Oil 161 Botton, microwave digestion on three replicates. Mean value (MV), standard deviation (STDEV) and relative standard deviation (RSD).
Element Wavelength [nm]
Al 396.152
Mg 279.553
Mo 202.030
Na 589.592
Ni 231.604
Zn 213.856
Fe 259.941
Micro BO1 [ppm] 55.9 0.435 0.202 8.01 2.33 0.656 0.921
Micro BO2 [ppm] 0.543 0.312 0.068 7.60 2.35 0.457 0.679
Micro BO3 [ppm] 0.515 0.472 0.092 9.03 2.71 0.806 1.03
MV BO [ppm] 19.0 0.406 0.121 8.21 2.46 0.639 0.878
STDEV [ppm] 32 0.08 0.07 0.74 0.21 0.17 0.18
RSD [%] 168 21 59 9.0 8.6 27 21
Element Wavelength [nm]
Cr 267.716
B 208.959
Cd 214.438
P 177.495
Ti 334.941
V 292.464
S 182.034
Micro BO1 [ppm] 0.082 1.18 0.038 20.9 0.333 0.553 4814
Micro BO2 [ppm] 0.085 0.831 0.041 21.3 0.172 0.504 4522
Micro BO3 [ppm] 0.114 1.32 0.042 17.2 0.237 0.502 4758
MV BO [ppm] 0.093 1.11 0.040 19.8 0.247 0.519 4698
STDEV [ppm] 0.02 0.25 0.002 2.3 0.08 0.03 155
RSD [%] 19 23 4.9 11 33 5.6 3.3
For the 161 botton oil more elements could be quantified, the concentrations are higher as well, which
probably is the main reason for the better RSD-results. The high RSD-values for aluminium and
10
molybdenum are due to the high values measured in the first replicate, and are marked in blue in the
table, they can probably be seen as outliners if more measurements were to be made.
Table 8: Oil RAFAP 2e91, microwave digestion on three replicates. Mean value (MV), standard deviation (STDEV) and relative standard deviation (RSD).
Element Wavelength [nm]
Al 396.152
Ba 455.404
Ca 393.366
K 766.491
Mg 279.553
Mo 202.030
Micro RF1 [ppm] 3.15 5.69 191 37.0 9.09 1.14
Micro RF2 [ppm] 2.34 5.74 191 43.3 8.92 1.14
Micro RF3 [ppm] 3.07 5.44 223 39.3 9.17 1.09
MV RF [ppm] 2.85 5.62 202 39.9 9.06 1.12
STDEV [ppm] 0.45 0.16 18 3.2 0.13 0.03
RSD [%] 16 2.9 9.1 8.0 1.4 2.5
Element Wavelength [nm]
Na 589.592
Zn 213.856
Cu 324.754
Fe 259.941
Cr 267.716
B 249.773
Micro RF1 [ppm] 479 11.3 0.09 3.26 0.655 17.7
Micro RF2 [ppm] 507 10.9 0.55 3.49 0.592 17.3
Micro RF3 [ppm] 486 10.3 0.73 3.57 0.868 17.1
MV RF [ppm] 491 10.8 0.46 3.44 0.705 17.4
STDEV [ppm] 14 0.52 0.33 0.16 0.14 0.31
RSD [%] 2.9 4.8 72 4.6 21 1.8
Element Wavelength [nm]
Cd 214.438
Mn 257.611
P 177.495
Ti 334.941
V 292.464
S 182.034
Micro RF1 [ppm] 0.276 8.65 53.3 0.171 13.7 7116
Micro RF2 [ppm] 0.258 8.54 52.8 0.079 13.5 6348
Micro RF3 [ppm] 0.303 8.73 59.4 0.176 13.3 7107
MV RF [ppm] 0.279 8.64 55.2 0.142 13.5 6857
STDEV [ppm] 0.02 0.10 3.6 0.05 0.18 441
RSD [%] 8.1 1.1 6.6 38 1.3 6.4
For the solid oil RAFAP 2e91 it was only nickel and lead that gave signals below LOQ, and the RSD-
values looks better.
In table 9 and 10 below, are the results from the ICP-AES measurements made with the open vessel
digestion. The concentrations have been recalculated to take into account the dilution and weight of
the oil sample. For all the measurements, see appendix A8, A9 and A10.
Table 9: Oil JL166DV, open vessel digestion on three replicates. Mean value (MV), standard deviation (STDEV) and relative standard deviation (RSD).
Element Wavelength [nm]
Na 589.592
Fe 259.941
P 177.495
Ti 334.941
S 182.034
Open JL1 [ppm] 5.57 0.023 18.4 0.130 1326
Open JL2 [ppm] 5.38 7.18 54.2 50.2 1374
Open JL3 [ppm] 4.49 0.707 28.4 33.7 1793
MV JL [ppm] 5.14 2.64 33.7 28.0 1498
STDEV [ppm] 0.6 4.0 18 26 257
RSD [%] 11 150 55 91 17
A different set of elements could be quantified in JL166DV when using the open vessel digestion
compared with the microwave digestion. Only phosphorus, titanium and sulphur could be quantified
in both. The values are lower for the microwave, but the RSD, however, are better. This becomes
11
strange when the results are compared to the measurements on the multi-element oil, since they gave
too low values on both phosphor and titanium for the open vessel digestion, but good recovery with
the microwave digestion.
The 161 botton oil sample weren’t analysed using the open vessel digestion, but the results from the
solid oil RAFAP 2e91 can be found in table 10 below.
Table 10: Oil RAFAP 2e91, open vessel digestion on three replicates. Mean value (MV), standard deviation (STDEV) and relative standard deviation (RSD).
Element Wavelength [nm]
Al 396.152
Ba 455.404
Ca 393.366
K 766.491
Mg 279.553
Mo 202.030
Na 589.592
Open RF1 [ppm] 5.93 11.9 281 62.5 13.0 0.609 795
Open RF2 [ppm] 6.91 9.66 234 82.1 15.2 8.11 946
Open RF3 [ppm] 5.72 13.7 309 71.9 14.4 0.326 891
MV RF [ppm] 6.19 11.8 275 72.2 14.2 3.01 877
STDEV [ppm] 0.63 2.0 38 9.8 1.1 4.4 77
RSD [%] 10 17 14 14 7.7 146 8.7
Element Wavelength [nm]
Ni 231.604
Zn 213.856
Cu 324.754
Fe 259.941
Cr 267.716
B 208.959
Cd 214.438
Open RF1 [ppm] 0.315 17.8 0.510 6.17 0.396 26.6 0.182
Open RF2 [ppm] 0.371 21.6 0.649 10.9 1.90 32.5 0.185
Open RF3 [ppm] 0.273 20.1 0.544 6.80 0.467 29.4 0.242
MV RF [ppm] 0.320 19.8 0.568 7.94 0.920 29.5 0.203
STDEV [ppm] 0.05 1.9 0.07 2.5 0.85 2.9 0.03
RSD [%] 15 9.6 13 32 92 10 17
Element Wavelength [nm]
Mn 257.611
P 177.495
Ti 334.941
V 292.464
S 182.034
Open RF1 [ppm] 12.6 72.1 1.30 20.3 17351
Open RF2 [ppm] 14.4 116 15.5 25.1 15945
Open RF3 [ppm] 14.3 79.3 -0.044 23.1 16781
MV RF [ppm] 13.8 89.0 5.57 22.9 16692
STDEV [ppm] 1.0 23 8.6 2.4 707
RSD [%] 7.4 26 154 10 4.2
All elements except for lead could be found using the open vessel digestion, but compared to the
microwave digestion, the open vessel digestion gives higher values on the standard deviation as well
as the RSD. For some of the elements, Mo, Cr and Ti, the RSD-values can be blamed on outliners, which
are marked in blue in the table. But the RSD are also higher for almost all the other elements as well.
The measured concentrations are higher for the open vessel compared to the microwave digestion,
but this will be discussed more below.
In figure 2, 3 and 4 below are bar charts comparing the mean values of the elements for the microwave
digestion and the open vessel digestion. The standard deviation-values are presented as well. The
reason that the results are divided in three different bar charts is because the concentrations of the
elements vary. Figure 3 shows the highest concentration, figure 4 the lowest and figure 2 the rest.
12
Figure 2: Oil RAFAP 2e91, ICP-AES measurements made after microwave digestion and open vessel digestion, with standard deviation for the methods on respective element.
Figure 3: Oil RAFAP 2e91, ICP-AES measurements made after microwave digestion and open vessel digestion, with standard deviation for the methods on respective element. Elements with relative high concentrations.
-5
0
5
10
15
20
25
30
35
Al 396,152 Ba 455,404 Mg 279,553 Zn 213,856 Fe 259,941 B 249,773 Mn 257,611 Ti 334,941 V 292,464
MV Micro RF MV Open RF
0
200
400
600
800
1000
1200
Ca 393,366 K 766,491 Na 589,592 P 177,495
MV Micro RF MV Open RF
13
Figure 4: Oil RAFAP 2e91, ICP-AES measurements made after microwave digestion and open vessel digestion, with standard deviation for the methods on respective element. Elements with relative low concentrations.
In the three figures it is easy to see the trend that concentrations measured after open vessel digestion
are higher than those measured after microwave digestion. But what also can be seen is that the
microwave digestion gives lower standard deviation for the elements, which means that the
microwave digestion gives better repeatability. For the low-concentration elements the uncertainty of
the values are considerably larger, especially for the open vessel digestion. Which probably is due to
that the low concentrations, almost as low as the blank, give less accuracy for the results.
It is difficult to say why the concentrations are systematically lower after microwave digestion
compared with the open vessel digestion. Since it is for all elements, one can rule out contamination
of the open vessel. Losses due to vaporization in the microwave bombs are also quite unlikely, since it
is a closed system, but there could still be losses in the sense that the oil have not been completely
digested. If the sample did not have enough time to digest, this would mean that some elements are
still bound in molecules and complexes, and could not be measured by the ICP.
The multi-element standard oils did, on the other hand, not seem to suffer from this problem, since
the recovery for the most elements were good, see results from standard oils. However, one credible
guess is that the lignin oils are more difficult to digest than the standard oil, since the lignin polymer
probably is bigger than the oil-molecule present in the multi-standard, which would make it more
difficult to break down.
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-1
0
1
2
3
4
5
6
7
8
Mo 202,030 Cu 324,754 Cr 267,716 Cd 214,438
MV Micro RF MV Open RF
14
Table 11 below shows the final compilation of the results.
Table 11: LOQ-values for the microwave digestion and open vessel digestion. Mean values from measurements on three different kinds of lignin oil after microwave digestion, and two oils after open vessel digestion.
Element Wavelength [nm]
Al 396.152
Ba 455.404
Ca 393.366
K 766.491
Mg 279.553
Mo 202.030
Na 589.592
Micro LOQ [ppm] 0.187 0.103 0.052 0.204 0.004 0.004 0.324
Micro JL [ppm] <0.187 <0.103 <0.052 <0.204 0.076 <0.004 <0.324
Micro BO [ppm] 0.529 <0.103 <0.052 <0.204 0.406 0.121 8.21
Micro RF [ppm] 2.85 5.62 202 39.9 9.06 1.12 491
Open LOD [ppm] 0.054 0.017 0.025 0.556 0.010 0.064 0.307
Open JL [ppm] <0.054 <0.017 <0.025 <0.556 <0.010 <0.064 5.14
Open RF [ppm] 6.19 11.8 275 72.2 14.2 3.01 877
Element Wavelength [nm]
Ni 231.604
Pb 220.353
Zn 213.856
Cu 324.754
Fe 259.941
Cr 267.716
B 208.959
Micro LOQ [ppm] 0.020 0.089 0.063 0.028 0.101 0.002 0.044
Micro JL [ppm] <0.020 <0.089 0.119 <0.028 <0.101 0.065 0.818
Micro BO [ppm] 2.46 <0.089 0.639 <0.028 0.878 0.093 1.11
Micro RF [ppm] <0.020 <0.089 10.81 0.458 3.44 0.705 17.4
Open LOD [ppm] 0.013 0.067 0.245 0.543 0.017 0.014 0.119
Open JL [ppm] <0.013 <0.067 <0.245 <0.543 2.64 <0.014 <0.119
Open RF [ppm] 0.320 0.121 19.8 0.568 7.94 0.920 29.5
Element Wavelength [nm]
Cd 214.438
Mn 257.611
P 177.495
Ti 334.941
V 292.464
S 182.034
Micro LOQ [ppm] 0.002 0.002 0.279 0.009 0.004 3.33
Micro JL [ppm] 0.026 <0.002 6.19 0.124 0.020 824
Micro BO [ppm] 0.040 <0.002 19.8 0.247 0.519 4698
Micro RF [ppm] 0.279 8.64 55.2 0.142 13.5 6857
Open LOD [ppm] 0.014 0.013 0.108 0.014 0.023 1.523
Open JL [ppm] <0.014 <0.013 33.7 28.0 <0.023 1498
Open RF [ppm] 0.203 13.8 89.0 5.57 22.9 16692
As can be seen in table 11, the LOQ-values are for the most part lower for the microwave digestion
compared with the open vessel, this is due to the lower standard deviation for the microwave
Conclusion and further testing Using microwave digestion as sample preparation shows good promise, since it gives good
repeatability, and low RSD- and LOQ-values, but more tests are needed, especially to decide the reason
for the elevated concentrations measured with the open vessel digestion compared with the
microwave digestion.
A recovery-test on the lignin oils using the method of spiking the sample with a known amount of an
element could give useful information about the microwave digestion.
If the multi-element standard oil were to be tested again, an ionization suppressor could be added, to
see if recovery for sodium and potassium can get better. CsCl could work, since Cs is more easily ionized
than K. (Harris, 2010)
15
References Cindric, I. J., Zeiner, M., & Steffan, I. (2007). Trace elemental characterization of edible oils by ICP–AES
and GFAAS. Microchemical Journal, 85(1):136-139.
Harris, D. C. (2010). Quantitative Chemical Analysis, Eighth Edition. USA: W.H. Freeman and Company.
Juranovic, I., Breinhoelder, P., & Steffan, I. (2003). Determination of trace elements in pumpkin seed
oils and pumpkin seeds by ICP-AES. Journal of analytical atomic spectrometry, 18(1):54-58.
Llorent-Martı´nez, E. J., Co´rdova, M. L.-d., Ortega-Barrales, P., & Ruiz-Medina, A. (2014). Quantitation
of Metals During the Extraction of Virgin Olive Oil from Olives Using ICP-MS after Microwave-
assisted Acid Digestion. Journal of the American Oil Chemists' Society, 91(10):1823-1830.
Mello, P. d., Pereira, J. S., Moraes, D. P., Dressler, V. L., Flores, E. M., & Knap, G. (2009). Nickel,
vanadium and sulfur determination by inductively coupled plasma optical emission
spectrometry in crude oil distillation residues after microwave-induced combustion. Journal of
analytical atomic spectrometry, 24(7):911-916.
Menga, Z., & Zhang, N. (2011). Rapid Analysis of Trace Nickel in Hydrogenated Cottonseed Oil by
Microwave Digestion Prior to Its Inductively Coupled Plasma Mass Spectrometry
Determination. Spectroscopy letters, 45(4):296-300.
RenFuel. (24-05-2015). RenFuel. Retrieved from http://renfuel.se/
Zakzeski, J., Bruijnincx, P. C., Jongerius, A. L., & Weckhuysen, B. M. (2010). The Catalytic Valorization of
Lignin for the Production of Renewable Chemicals. Chemical reviews, 110(6):3552–3599.
Zeinera, M., Steffana, I., & Cindric, I. J. (2005). Determination of trace elements in olive oil by ICP-AES
and ETA-AAS:. Microchemical Journal, 82(2):171-176.
‘
16
Appendix
Standard oils A 1: ICP-AES measurements made on multi-element standard oil after open vessel digestion and microwave digestion.
Al
167.078 Al
396.152 Ag
328.068 Ag
338.289 Ba
455.404 Ba
233.527 Ca
396.847 Ca
393.366 K
766.491 Mg
279.553
Open Blank 1 -0.05055 0.023031 0.000489 -0.00263 -0.01576 -0.01146 -0.08765 -0.12001 0.12255 -0.03394
Open Blank 2 -0.05072 0.021304 -0.00089 -0.00421 -0.01581 -0.0117 -0.08786 -0.1202 0.08442 -0.03444
Open M1 1.354681 1.193474 1.332566 1.333714 1.31388 1.26493 1.318221 1.334951 0.99131 1.39177
Open M2 1.369916 1.224087 1.337959 1.333038 1.57232 1.5262 1.310461 1.337879 0.94043 1.38559
Micro Blank 1 -0.04559 0.02619 -0.00064 -0.0046 -0.01578 -0.01183 -0.09021 -0.12279 -0.03906 -0.03516
Micro Blank 2 0.03856 0.0869 -0.00158 -0.0056 -0.01587 -0.01199 -0.09113 -0.12375 -0.06741 -0.03531
Micro M1 2.397804 2.042126 1.551448 1.556547 1.52032 1.48296 1.583912 1.554438 0.93438 1.6873
Micro M2 1.520471 1.32971 1.417117 1.388987 1.36853 1.32618 1.413593 1.387732 0.82646 1.51586
Micro M3 1.667136 1.444374 1.517623 1.510682 1.47979 1.44752 1.542816 1.561219 0.88257 1.61934
Mg
280.270 Mo
202.030 Mo
281.615 Na
589.592 Na
588.995 Ni
231.604 Pb
220.353 Pb
168.215 Zn
213.856 Zn
206.191
Open Blank 1 -0.02233 -0.00853 0.00723 0.09836 0.08151 -0.02251 -0.01279 -0.01895 -0.01326 -0.03359
Open Blank 2 -0.02277 -0.01221 0.00294 0.09426 0.07649 -0.0225 -0.01312 -0.01974 -0.01339 -0.03391
Open M1 1.31143 1.11661 1.10095 1.05961 1.09167 1.390384 1.322199 1.274455 1.335975 1.343646
Open M2 1.32127 1.23203 1.2057 1.05475 1.07741 1.392609 1.497671 1.457599 1.278513 1.306465
Micro Blank 1 -0.02344 -0.00859 0.00889 0.06467 0.04536 -0.02269 -0.01124 -0.02164 -0.01185 -0.03245
Micro Blank 2 -0.02357 -0.01255 0.00514 0.06501 0.0455 -0.02235 -0.01047 -0.0193 -0.01338 -0.03422
Micro M1 1.60309 1.55943 1.53398 1.18621 1.21984 1.642931 1.612772 1.566861 1.490223 1.559947
Micro M2 1.43132 1.39078 1.35889 1.07439 1.10152 1.468171 1.445603 1.384644 1.323943 1.378984
Micro M3 1.53926 1.51372 1.48615 1.16164 1.18571 1.602333 1.53996 1.480193 1.435956 1.495491
Cu
324.754 Cu
327.396 Fe
259.941 Fe
238.204 Cr
267.716 Cr
205.552 B
249.773 B
208.959 Cd
214.438 Cd
226.502
Open Blank 1 -0.01322 -0.01326 -0.01079 -0.01649 -0.00462 -0.01711 -0.02593 -0.02785 -0.00826 -0.00859
Open Blank 2 -0.01322 -0.01351 -0.0115 -0.01724 -0.00484 -0.01693 -0.02819 -0.03047 -0.0083 -0.00873
Open M1 1.32664 1.296365 1.102427 1.095059 1.281592 1.265841 1.13585 1.13601 1.31511 1.31444
Open M2 1.359869 1.337559 1.420569 1.427778 1.29188 1.282856 1.14683 1.12487 1.28441 1.30333
Micro Blank 1 -0.01302 -0.01265 -0.00957 -0.01557 -0.00418 -0.01701 -0.02788 -0.03291 -0.00825 -0.00899
Micro Blank 2 -0.01304 -0.01351 -0.01095 -0.01661 -0.00468 -0.01696 -0.03122 -0.03619 -0.00836 -0.00895
Micro M1 1.636292 1.611535 1.639505 1.639104 1.59791 1.576926 1.31125 1.27003 1.53544 1.52412
Micro M2 1.48733 1.470547 1.458764 1.457403 1.416031 1.395358 1.17948 1.13531 1.35695 1.35597
Micro M3 1.605359 1.579356 1.582551 1.587997 1.539399 1.507816 1.27879 1.2261 1.46072 1.47499
Mn
257.611 Mn
259.373 P
177.495 P
178.287 Ti
334.941 Ti
336.121 V
292.464 V
311.071
Open Blank 1 -0.01938 -0.01579 0.00607 -0.04315 -0.02109 -0.01928 -0.00692 -0.00175
Open Blank 2 -0.01948 -0.01588 0.00576 -0.04222 0.03646 0.03839 -0.00695 -0.00115
Open M1 1.38297 1.37093 0.64194 0.49628 0.304 0.3033 1.24085 1.27415
Open M2 1.3902 1.37536 0.86392 0.78089 0.62387 0.62511 1.2881 1.32598
Micro Blank 1 -0.0194 -0.01575 0.00117 -0.03563 -0.02083 -0.01866 -0.00737 -0.00125
Micro Blank 2 -0.0195 -0.01593 0.00104 -0.03667 -0.02104 -0.01894 -0.00747 -0.0011
Micro M1 1.69817 1.68153 1.63863 1.70861 1.61297 1.62395 1.58114 1.64054
Micro M2 1.53892 1.52226 1.50326 1.57182 1.45942 1.46007 1.40152 1.49336
Micro M3 1.65254 1.64156 1.59184 1.68437 1.56534 1.56946 1.53479 1.58511
17
A 2: ICP-AES measurements made on multi-element standard oil after open vessel digestion and microwave digestion, recalculated by subtracting the blank and taking dilution and weight of the sample into account.
Al
167.078 Al
396.152 Ag
328.068 Ag
338.289 Ba
455.404 Ba
233.527 Ca
396.847 Ca
393.366 K
766.491 Mg
279.553
Open M1 344.95 287.51 327.14 328.21 326.38 313.33 345.11 357.16 217.92 350.01
Open M2 343.13 290.32 323.23 322.82 383.60 371.44 337.73 352.17 202.16 342.94
Micro M1 466.64 385.85 301.70 303.47 298.51 290.49 325.41 326.02 191.92 334.73
Micro M2 325.92 272.28 303.30 298.14 296.06 286.16 321.70 323.14 188.13 331.71
Micro M3 335.88 279.02 305.33 304.74 300.69 293.41 328.40 338.66 188.14 332.64
MV Open 344.04 288.91 325.18 325.51 326.38 313.33 341.42 354.66 210.04 346.48
MV Micro 330.90 275.65 303.45 302.12 298.42 290.02 325.17 329.27 189.40 333.03
Mg
280.270 Mo
202.030 Mo
281.615 Na
589.592 Na
588.995 Ni
231.604 Pb
220.353 Pb
168.215 Zn
213.856 Zn
206.191
Open M1 327.44 276.63 268.99 236.45 248.57 346.81 327.72 317.57 331.20 338.09
Open M2 324.59 300.10 290.00 231.51 241.16 341.82 364.88 356.75 312.04 323.72
Micro M1 316.09 305.09 296.73 217.91 228.22 323.64 315.51 308.46 292.04 309.61
Micro M2 311.13 299.69 289.11 215.90 225.85 318.80 311.48 300.50 285.83 302.03
Micro M3 314.19 306.45 297.37 220.51 229.25 326.67 311.78 301.70 291.23 307.36
MV Open 326.02 288.36 279.50 233.98 244.87 344.31 327.72 317.57 321.62 330.91
MV Micro 313.80 303.74 294.40 218.11 227.77 323.03 312.92 303.55 289.70 306.34
Cu
324.754 Cu
327.396 Fe
259.941 Fe
238.204 Cr
267.716 Cr
205.552 B
249.773 B
208.959 Cd
214.438 Cd
226.502
Open M1 328.88 321.49 273.34 272.93 315.74 314.89 285.45 286.00 324.84 324.77
Open M2 331.66 326.31 345.82 348.95 313.19 313.98 283.55 278.75 312.24 316.91
Micro M1 320.51 315.70 320.59 321.65 311.38 309.74 260.55 253.51 299.99 297.92
Micro M2 320.86 317.29 314.16 315.12 303.78 302.04 258.56 250.18 291.97 291.90
Micro M3 325.37 320.15 320.23 322.49 310.38 306.55 263.04 253.45 295.34 298.34
MV Open 330.27 323.90 273.34 272.93 314.47 314.44 284.50 282.38 318.54 320.84
MV Micro 322.25 317.71 318.33 319.75 308.51 306.11 260.72 252.38 295.77 296.06
Mn
257.611 Mn
259.373 P
177.495 P
178.287 Ti
334.941 Ti
336.121 V
292.464 V
311.071
Open M1 344.23 340.39 156.12 132.29 72.73 72.10 306.28 313.11
Open M2 340.49 336.04 207.25 198.93 148.84 148.68 312.81 320.64
Micro M1 333.78 329.84 318.21 339.05 317.51 319.23 308.70 319.03
Micro M2 333.27 328.93 321.25 343.88 316.59 316.27 301.31 319.62
Micro M3 336.15 333.21 319.81 345.90 318.91 319.31 310.05 318.92
MV Open 342.36 338.22 207.25 198.93 148.84 148.68 309.55 316.87
MV Micro 334.40 330.66 319.76 342.94 317.67 318.27 306.69 319.19
A 3: ICP-AES measurements made on sulphur standard oil after open vessel digestion and microwave digestion.
S
180.731 S
182.034
Open S1 2.9667 2.7664
Open S2 3.0489 2.9147
Micro S1 2.6935 2.5602
Micro S2 2.6585 2.4907
Micro S3 2.6744 2.4709
18
A 4: ICP-AES measurements made on sulphur standard oil after open vessel digestion and microwave digestion, recalculated by subtracting the blank and taking dilution and weight of the sample into account.
S 180.731 S 182.034
Open S1 6965.8 6584.0
Open S2 6716.8 6500.8
Micro S1 6147.7 5958.9
Micro S2 6049.6 5783.9
Micro S3 6182.5 5831.2
Lignin oils A 5: ICP-AES measurements made on JL166DV, 161 botton and RAFAP 2e91 after microwave digestion.
Al
167.078 Al
396.152 Ba
455.404 Ba
233.527 Ca
396.847 Ca
393.366 K
766.491 Mg
279.553 Mg
280.270 Mo
202.030
Micro Blank 1 0.04551 0.11631 -0.02243 -0.02199 0.09291 0.09068 -0.06535 -0.0371 -0.00672 -0.00362
Micro Blank 2 -0.01079 0.07852 -0.03462 -0.03412 0.09393 0.09227 -0.10661 -0.03766 -0.00723 -0.01167
Micro Blank 3 0.0143 0.09616 -0.04314 -0.04268 0.10254 0.10102 -0.08757 -0.03795 -0.00751 -0.01315
Micro JL1 0.0123 0.0972 -0.05105 -0.04807 0.10604 0.10504 -0.14206 -0.03531 -0.00496 -0.01317
Micro JL2 -0.00985 0.07746 -0.05756 -0.05547 0.07919 0.07475 -0.17752 -0.0366 -0.00615 -0.01299
Micro JL3 0.05474 0.12333 -0.06268 -0.06062 0.08267 0.07966 -0.19077 -0.03689 -0.00651 -0.01352
Micro BO1 1.43296 1.05342 -0.07119 -0.06996 0.08404 0.08 -0.1656 -0.03013 -0.00002 -0.00603
Micro BO2 0.00798 0.10613 -0.07449 -0.07403 0.07065 0.06739 -0.17426 -0.03233 -0.00227 -0.00833
Micro BO3 0.01228 0.10578 -0.07705 -0.07465 0.26512 0.26911 -0.1655 -0.02953 0.00059 -0.00791
Micro RF1 0.06643 0.14893 0.06032 0.06709 3.24369 3.20804 0.52361 0.1123 0.13356 0.00935
Micro RF2 0.03458 0.13637 0.0632 0.06464 3.312 3.33006 0.64295 0.11248 0.13267 0.00969
Micro RF3 0.05837 0.14789 0.0569 0.06446 3.79593 3.80191 0.56588 0.11457 0.13365 0.00864
Mo
281.615 Na
589.592 Na
588.995 Ni
231.604 Pb
220.353 Pb
168.215 Zn
213.856 Zn
206.191 Cu
324.754 Cu
327.396
Micro Blank 1 0.00327 0.20564 0.19244 -0.01288 -0.02833 -0.22374 0.02459 0.00775 0.00273 0.00251
Micro Blank 2 -0.00246 0.23229 0.22058 -0.01594 -0.03901 -0.31529 0.01304 -0.00398 0.00298 0.00289
Micro Blank 3 -0.00417 0.27076 0.26332 -0.01677 -0.04627 -0.34014 0.01433 -0.00268 0.00768 0.00723
Micro JL1 -0.00387 0.20229 0.18856 -0.02015 -0.04392 -0.46199 0.01927 0.00213 0.00023 -0.00072
Micro JL2 -0.00511 0.19657 0.18154 -0.01374 -0.0478 -0.38476 0.01862 0.00095 -0.00074 -0.00126
Micro JL3 -0.00409 0.19464 0.17986 -0.01542 -0.05335 -0.42953 0.02015 0.00289 -0.0016 -0.00237
Micro BO1 0.00509 0.37331 0.37301 0.02463 -0.05961 -0.76794 0.02854 0.01371 0.00092 0.00015
Micro BO2 0.00387 0.36392 0.36116 0.02435 -0.06306 -0.77291 0.025 0.00986 -0.00139 -0.00148
Micro BO3 0.00217 0.39014 0.39471 0.03092 -0.06455 -0.67403 0.03105 0.01623 -0.00103 -0.0018
Micro RF1 0.02604 8.13018 7.85625 -0.02306 -0.05445 -0.60707 0.20374 0.26489 0.006 0.0055
Micro RF2 0.02522 8.7659 8.3354 -0.0279 -0.05848 -0.67349 0.20004 0.25605 0.01374 0.01265
Micro RF3 0.02573 8.30986 7.97432 -0.02956 -0.05523 -0.67874 0.18782 0.26192 0.01656 0.01583
Fe
259.941 Fe
238.204 Cr
267.716 Cr
205.552 B
249.773 B
208.959 Cd
214.438 Cd
226.502 Mn
257.611 Mn
259.373
Micro Blank 1 0.0111 0.00427 0.00503 -0.01235 0.00348 0.00831 -0.01172 -0.00094 -0.01281 -0.00971
Micro Blank 2 0.0303 0.02356 0.00546 -0.01167 0.00199 0.00366 -0.01174 -0.00103 -0.0127 -0.0097
Micro Blank 3 0.01486 0.00727 0.00521 -0.01223 -0.00263 -0.00058 -0.012 -0.00096 -0.01234 -0.00938
Micro JL1 0.01478 0.00769 0.0061 -0.01191 0.02271 0.0197 -0.01132 -0.00165 -0.01291 -0.01004
Micro JL2 0.02376 0.01619 0.00668 -0.01141 0.01858 0.01833 -0.01146 -0.0017 -0.01296 -0.01017
Micro JL3 0.01411 0.00669 0.00624 -0.01173 0.0158 0.01531 -0.01134 -0.00164 -0.01276 -0.00993
Micro BO1 0.03452 0.02763 0.00663 -0.01267 0.03329 0.02398 -0.01117 -0.00156 -0.01269 -0.00988
Micro BO2 0.03016 0.02384 0.00666 -0.01246 0.03102 0.01777 -0.01113 -0.00158 -0.01286 -0.01
Micro BO3 0.03639 0.02885 0.00717 -0.01155 0.03288 0.02634 -0.01111 -0.00146 -0.01268 -0.00989
Micro RF1 0.07251 0.07239 0.01603 -0.01555 0.31561 0.29538 -0.00728 -0.00585 0.12998 0.12535
Micro RF2 0.07747 0.0767 0.0152 -0.01577 0.31846 0.29463 -0.00747 -0.00554 0.13104 0.12797
Micro RF3 0.07798 0.07878 0.01965 -0.01622 0.3148 0.28739 -0.00679 -0.00803 0.13223 0.12709
19
P
177.495 P
178.287 Ti
334.941 Ti
336.121 V
292.464 V
311.071 S
180.731 S
182.034
Micro Blank 1 0.13738 0.12534 0.00256 0.00485 -0.0046 0.01187 -1.10561 -1.32242
Micro Blank 2 0.18028 0.16312 0.00183 0.00422 -0.0053 0.01128 -1.45734 -1.77339
Micro Blank 3 0.19062 0.16509 0.0007 0.00265 -0.00529 0.01056 -1.67594 -1.98134
Micro JL1 0.30917 0.26215 0.00408 0.00655 -0.00483 0.0108 13.0052 12.6443
Micro JL2 0.2507 0.20305 0.00343 0.00604 -0.00461 0.01075 12.9093 12.5814
Micro JL3 0.2659 0.22136 0.00395 0.00653 -0.00523 0.01025 12.3708 11.9233
Micro BO1 0.52733 0.45658 0.00739 0.00966 0.0044 0.02012 85.6114 86.2401
Micro BO2 0.528 0.46373 0.00459 0.00706 0.0034 0.0197 83.8525 84.0457
Micro BO3 0.46309 0.40771 0.00574 0.0084 0.00349 0.01975 86.5369 87.1792
Micro RF1 1.048 1.09058 0.00452 0.01206 0.21993 0.24877 119.445 121.804
Micro RF2 1.05867 1.10276 0.00303 0.00988 0.2215 0.25111 118.849 120.711
Micro RF3 1.15496 1.20064 0.00461 0.01341 0.21571 0.24989 117.827 119.806
A 6: ICP-AES measurements made on further diluted sampels of 161 botton and RAFAP 2e91 after microwave digestion.
S
180.731 S
182.034
Blank 1d -1.57374 -1.5991
Blank 2d -1.3493 -1.35288
Blank 3d -0.8492 -0.87703
BO1d 1.76321 1.66622
BO2d 1.52024 1.43785
BO3d 1.72428 1.62
RF1d 2.99316 2.91166
RF2d 2.57286 2.53881
RF3d 2.971 2.93729
A 7: ICP-AES measurements made on JL166DV, 161 botton and RAFAP 2e91 after microwave digestion, recalculated by subtracting the blank and taking dilution and weight of the sample into account.
Al
396.152 Ba
455.404 Ca
393.366 K
766.491 Mg
279.553 Mo
202.030 Na
589.592 Ni
231.604
Micro LOQ 0.18720 0.10305 0.05237 0.20444 0.00428 0.00428 0.32411 0.02028
Micro Blank 0.09700 -0.03340 0.09646 -0.08651 -0.03757 -0.00948 0.23623 -0.01520
Micro JL1 0.01183 -1.02678 0.55721 -3.23099 0.13145 -0.21462 -1.97408 -0.28810
Micro JL2 -1.13822 -1.40777 -1.00616 -5.30229 0.05651 -0.20449 -2.31061 0.08487
Micro JL3 1.55753 -1.73201 -0.81563 -6.16662 0.04022 -0.23895 -2.45991 -0.01321
Micro BO1 55.88450 -2.20829 -0.72571 -4.62129 0.43472 0.20159 8.00968 2.32710
Micro BO2 0.54342 -2.44499 -1.53566 -5.22099 0.31177 0.06842 7.59737 2.35297
Micro BO3 0.51537 -2.56139 9.89623 -4.63479 0.47175 0.09212 9.03076 2.70592
Micro RF1 3.15157 5.68718 190.98925 37.02505 9.09484 1.14270 479.04335 -0.47719
Micro RF2 2.33967 5.74004 191.07623 43.34652 8.91638 1.13913 506.85645 -0.75487
Micro RF3 3.06586 5.43956 222.85964 39.30060 9.16506 1.09157 486.36325 -0.86526
Pb
220.353 Zn
213.856 Cu
324.754 Fe
259.941 Cr
267.716 B
208.959 Cd
214.438 Mn
257.611
Micro LOQ 0.08934 0.06266 0.02761 0.10073 0.00214 0.04402 0.00155 0.00243
Micro Blank -0.03787 0.01732 0.00446 0.01875 0.00523 0.00380 -0.01182 -0.01262
Micro JL1 -0.35189 0.11342 -0.24623 -0.23110 0.05041 0.92500 0.02908 -0.01706
Micro JL2 -0.57853 0.07574 -0.30315 0.29169 0.08428 0.84672 0.02097 -0.02000
Micro JL3 -0.91559 0.16738 -0.35863 -0.27464 0.05954 0.68097 0.02839 -0.00848
Micro BO1 -1.27028 0.65559 -0.20704 0.92126 0.08161 1.17933 0.03798 -0.00428
Micro BO2 -1.49877 0.45695 -0.34826 0.67868 0.08488 0.83139 0.04105 -0.01448
Micro BO3 -1.56547 0.80562 -0.32232 1.03484 0.11364 1.32274 0.04166 -0.00372
20
Micro RF1 -1.00616 11.31287 0.09325 3.26222 0.65519 17.69470 0.27551 8.65346
Micro RF2 -1.22470 10.85772 0.55125 3.48911 0.59225 17.28212 0.25849 8.53647
Micro RF3 -1.04578 10.27108 0.72871 3.56787 0.86847 17.08394 0.30301 8.72570
P
177.495 Ti
334.941 V
292.464 S
182.034
Micro LOQ 0.27948 0.00928 0.00397 3.3348
Micro Blank 0.16943 0.00170 -0.00506 -1.6924
Micro JL1 8.12799 0.13862 0.01357 833.8744
Micro JL2 4.73503 0.10098 0.02641 831.5979
Micro JL3 5.70607 0.13328 -0.00986 805.3214
Micro BO1 20.91255 0.33267 0.55295 4814.1996
Micro BO2 21.33458 0.17215 0.50356 4521.7219
Micro BO3 17.23087 0.23725 0.50187 4758.4408
Micro RF1 53.31611 0.17133 13.6537 7116.1452
Micro RF2 52.84128 0.07923 13.4630 6347.7822
Micro RF3 59.36948 0.17550 13.2996 7107.3221
A 8: ICP-AES measurements made on JL166DV and RAFAP 2e91 after open vessel digestion.
Al
167.078 Al
396.152 Ba
455.404 Ba
233.527 Ca
396.847 Ca
393.366 K
766.491 Mg
279.553 Mg
280.270 Mo
202.030
Open Blank1 -0.03929 0.04548 -0.01034 -0.01173 -0.01911 -0.04506 -0.05402 -0.03882 -0.01775 -0.00361
Open Blank2 -0.04684 0.03777 -0.01277 -0.01319 -0.01561 -0.04146 -0.13346 -0.03746 -0.01648 -0.0127
Open JL1 -0.06303 0.04517 -0.01357 -0.01316 -0.019 -0.04504 -0.139 -0.03893 -0.01791 -0.01396
Open JL2 -0.02914 0.06965 -0.00519 -0.00658 -0.02472 -0.05103 -0.15371 -0.03596 -0.01516 0.06996
Open JL3 -0.07526 0.04455 -0.01437 -0.01407 -0.02417 -0.05022 -0.21038 -0.03959 -0.01857 -0.01416
Open RF1 0.04021 0.12881 0.15606 0.15526 3.89832 3.90428 0.78405 0.14478 0.15438 0.00039
Open RF2 0.05326 0.14119 0.12311 0.12265 3.15119 3.2146 1.05091 0.17372 0.183 0.1049
Open RF3 0.03918 0.13209 0.18586 0.18492 4.4121 4.39767 0.93997 0.16891 0.17688 -0.00346
Mo
281.615 Na
589.592 Na
588.995 Ni
231.604 Pb
220.353 Pb
168.215 Zn
213.856 Zn
206.191 Cu
324.754 Cu
327.396
Open Blank1 0.00431 0.01709 -0.00343 -0.0102 -0.00498 -0.02075 0.05123 0.02555 0.07519 0.07584
Open Blank2 -0.00204 0.06101 0.04369 -0.01209 -0.01461 -0.02187 0.01624 -0.00828 -0.00239 -0.00417
Open JL1 -0.00052 0.12015 0.10517 -0.0206 -0.0201 -0.45756 0.01606 -0.00715 -0.00521 -0.00883
Open JL2 0.08213 0.11427 0.09799 -0.01886 -0.01956 -0.45584 0.01806 -0.00425 -0.00448 -0.00826
Open JL3 0.00177 0.10063 0.08389 -0.02786 -0.01997 -0.6577 0.01561 -0.00735 -0.00582 -0.00942
Open RF1 0.01763 11.1928 10.4313 -0.00672 -0.01001 -0.40894 0.28363 0.29464 0.00477 0.00111
Open RF2 0.11964 13.2252 12.233 -0.00597 -0.00962 -0.43727 0.33452 0.34724 0.00666 0.00328
Open RF3 0.01456 12.8609 11.809 -0.00722 -0.00452 -0.47446 0.32335 0.35041 0.00544 0.00283
Fe
259.941 Fe
238.204 Cr
267.716 Cr
205.552 B
249.773 B
208.959 Cd
214.438 Cd
226.502 Mn
257.611 Mn
259.373
Open Blank1 -0.00244 -0.00777 -0.00504 -0.0138 0.00191 0.01998 0.00573 0.00543 -0.03094 -0.0211
Open Blank2 -0.00488 -0.00962 -0.00703 -0.01568 -0.01246 0.003 0.00366 0.00412 -0.03283 -0.02282
Open JL1 -0.00332 -0.00885 -0.00735 -0.01728 -0.01802 -0.0132 0.00346 0.00446 -0.03287 -0.02269
Open JL2 0.09685 0.091 0.02782 0.01976 -0.01975 -0.0121 0.0034 0.00456 -0.02979 -0.01913
Open JL3 0.00604 0.00084 -0.00686 -0.0173 -0.00741 -0.00934 0.00349 0.00419 -0.03289 -0.02273
Open RF1 0.08296 0.08056 -0.00048 -0.01324 0.4159 0.3853 0.00725 0.00579 0.14476 0.15234
Open RF2 0.14763 0.14579 0.02043 0.00729 0.49503 0.46478 0.00727 0.00596 0.16882 0.17712
Open RF3 0.0941 0.09219 0.00069 -0.01343 0.47896 0.43475 0.00818 0.00567 0.1735 0.18124
P
177.495 P
178.287 Ti
334.941 Ti
336.121 V
292.464 V
311.071 S
180.731 S
182.034
Open Blank1 -0.02002 0.01861 -0.00938 -0.01176 0.00054 0.00439 -4.01893 -4.07807
Open Blank2 -0.00456 -0.00049 -0.01134 -0.01422 -0.00271 0.00178 -3.67654 -3.86047
Open JL1 0.25514 0.23081 -0.00847 -0.01256 -0.00323 0.0033 15.4605 15.3447
Open JL2 0.74597 0.76292 0.69159 0.68592 0.02006 0.0335 15.5089 15.262
Open JL3 0.37741 0.35292 0.45206 0.44963 -0.00288 0.00856 21.5686 20.6183
21
Open RF1 1.00008 1.10833 0.00782 0.00575 0.28451 0.29996 220.819 225.657
Open RF2 1.59862 1.79457 0.20527 0.20321 0.34885 0.37141 263.381 272.12
Open RF3 1.12855 1.25937 -0.01099 -0.01175 0.33194 0.34923 240.078 244.907
A 9: ICP-AES measurements made on further diluted sampels of RAFAP 2e91 after open vessel digestion.
S
180.731 S
182.034
Open R1d 1.3859 0.90152
Open R2d 1.0046 0.47708
Open R3d 1.4048 0.85882
A 10: ICP-AES measurements made on JL166DV and RAFAP 2e91 after open vessel digestion, recalculated by subtracting the blank and taking dilution and weight of the sample into account.
Al
396.152 Ba
455.404 Ca
393.366 K
766.491 Mg
279.553 Mo
202.030 Na
589.592 Ni
231.604 Pb
220.353 Zn
213.856
Open LOQ 0.00386 0.00122 0.00180 0.03972 0.00068 0.00455 0.02196 0.00095 0.00482 0.01750
Open JL1 -1.37082 -0.13835 -0.12222 -3.10760 -0.05424 -0.39858 5.56842 -0.64919 -0.70755 -1.21359
Open JL2 0.99515 0.45487 -0.55528 -4.28576 0.15579 5.58249 5.37560 -0.55135 -0.69786 -1.12021
Open JL3 -2.34755 -0.20526 -0.50750 -8.50500 -0.10573 -0.43786 4.49021 -1.21880 -0.74193 -1.32161
Open RF1 5.9331 11.9420 281.2497 62.5397 13.0325 0.60880 794.669 0.31527 -0.01532 17.80422
Open RF2 6.9086 9.6584 233.6580 82.0958 15.1949 8.10845 945.728 0.37116 0.01255 21.57269
Open RF3 5.7171 13.7230 308.7042 71.8567 14.3928 0.32637 891.290 0.27284 0.36668 20.13213
Cu
324.754 Fe
259.941 Cr
267.716 B
208.959 Cd
214.438 Mn
257.611 P
177.495 Ti
334.941 V
292.464 S
182.034
Open LOQ 0.03879 0.00122 0.00100 0.00849 0.00104 0.00095 0.00773 0.00098 0.00163 0.10880
Open JL1 -0.19362 0.02334 -0.09029 -1.69524 -0.08480 -0.06763 18.36204 0.12977 -0.14728 1326.119
Open JL2 -0.14936 7.18295 2.41945 -1.68586 -0.09255 0.14972 54.18908 50.16488 1.51113 1374.363
Open JL3 -0.25010 0.70729 -0.06016 -1.51885 -0.08786 -0.07328 28.41563 33.71813 -0.13089 1792.844
Open RF1 0.51013 6.17140 0.39578 26.63277 0.18204 12.58539 72.12814 1.29527 20.34774 17351.415
Open RF2 0.64908 10.85072 1.89810 32.51055 0.18468 14.39483 115.53658 15.46527 25.09780 15944.903
Open RF3 0.54429 6.79563 0.46748 29.42224 0.24225 14.27701 79.30367 -0.04379 23.14970 16780.849
