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Agilent Analysis of flue gas desulfurization wastewaters by Agilent 7700x ICP-MS Manual

1. 0 1 5060 45 5121 08 1 2 5444 41 5340 90 1 9 60 Ni 25 17 20 08 20 2 19 00 23 07 21 4 20 53 19 39 5 5 63 Cu 19 26 19 53 1 4 19 45 18 73 3 7 19 22 19 23 0 1 66 Zn 21 44 21 27 0 8 20 47 21 73 6 1 21 02 18 23 13 3 75 As 25 71 22 84 11 2 24 07 24 08 0 0 24 18 22 80 5 7 107 Ag 6 02 2 87 52 3 5 75 8 30 44 3 5 22 6 02 15 2 111 Cd 17 69 20 06 13 4 17 48 18 19 4 0 19 00 18 71 1 5 121 Sb 21 42 22 69 5 9 21 61 21 65 0 2 22 38 21 82 2 5 205 TI 20 79 20 45 1 7 20 44 20 54 0 5 21 08 20 53 2 6 208 Pb 19 40 19 62 1 1 19 47 19 73 1 3 19 30 19 27 0 2 Conclusions Flue gas desulfurization FGD wastewater samples are extremely challenging due to their high and variable matrix composition and the fact that most of the required analytes can suffer from overlap from matrix based polyatomic interferences However the new EPA method development and validation has demonstrated that these difficult sample matrices can be routinely analyzed for trace metal contaminants using the Agilent 7700x ICP MS with optional ISIS DS discrete sampling accessory Based on extensive initial validation and strict ongoing EPA mandated quality control the new method has been shown to be simple robust and reliable Using the combined advantages of a highly robust plasma HMI aerosol dilution helium collision mode to eliminate interferences and discrete sampling this method has achieved performance comparable to that which would normally
2. be expected when analyzing much simpler samples such as waters and soil digests References 1 Technical Support Document for the Preliminary 2010 Effluent Guidelines Program Plan 40 CFR Part 423 10 WWW epa gov www agilent com chem Agilent Technologies Inc 2011 Published May 30 2011 Publication Number 5990 8114EN Agilent Technologies
3. to typical EPA criteria Each group of 10 samples must include one laboratory control sample LCS of known concentration and one matrix spike matrix spike duplicate MS MSD pair in addition to 7 unknown samples After each block of 10 samples calibration and blank levels were verified through the analysis of a CCV and CCB standard Figure 1 Additionally internal standards were monitored for all samples and easily met the requirement to fall within 60 125 of the intensity measured in the calibration blank Figure 2 Internal standard recoveries provide information on sample specific matrix effects as well as long term instrument drift 140 0 130 0 78 Se e 51 V 120 0 POD ae 57 Cr 110 0 55 Mn eee 100 0 gt 60 Ni 63 Cu 90 0 de LE ELEE EEE EEEL EEE rr rr 66 Zn 80 0 75 As 70 0 107 Ag 111 Cd 60 0 121 Sb SES 205 TI 40 0 T T T T T T 208 Pb ccv1 ccv2 CCv3 ccv4 CCV5 CCV6 CCV7 CcCV8 Figure 1 CCV recoveries over a sequence of 88 analyses including real FGD samples all required OC samples and synthetic FGD matrix samples Control limits 85 115 are indicated in red Internal standard recoveries for the 88 sample validation sequence are shown in Figure 2 All samples met the ISTD OC requirements of 60 125 recovery and total instrument drift over the course of the sequence was less than 10 as indicated by the ISTD response for the fi
4. Authors Richard Burrows TestAmerica Laboratories Inc USA Steve Wilbur Agilent Technologies Inc USA Analysis of flue gas desulfurization wastewaters by Agilent 7700x ICP MS Application Note Environmental Introduction The U S Environmental Protection Agency USEPA is in the process of revising effluent guidelines for the steam electric power generating industry due to increases in wastewater discharges as a result of Phase 2 of the Clean Air Act amendments These regulations require S02 scrubbing for most coal fired plants resulting in Flue Gas Desulfurization FGD wastewaters The revised effluent guidelines will apply to plants primarily engaged in the generation of electricity for distribution and sale which results primarily from a process utilizing fossil type fuel coal oil or gas or nuclear fuel in conjunction with a thermal cycle employing the steam water system as the thermodynamic medium 1 This includes most large scale power plants in the United States Effluents from these plants especially coal fired plants can contain several hundred to several thousand ppm of calcium magnesium manganese sodium boron chloride nitrate and sulfate Measurement of low ppb levels of toxic metals including As Cd Cr Cu Pb Se TI V and Zn in this matrix presents a challenge for ICP MS due os Agilent Technologies to the very high dissolved solids levels and potential interferences from matrix based po
5. V 51 0 05 He Sc 0 08 0 42 Cr 52 0 05 He Sc 0 17 Mn 55 0 05 He Sc 0 44 0 68 Ni 60 0 05 He Sc 0 17 0 45 Cu 63 0 05 He Sc 0 15 0 48 Zn 66 0 05 He Ge 0 94 2 04 As 75 0 1 He Ge 0 49 0 61 Se 78 0 05 H2 Ge 0 08 0 31 Ag 107 0 05 He In 0 02 0 29 Cd 111 0 05 He In 0 19 0 59 Sb 121 0 05 He In 0 05 0 36 TI 205 0 05 He Ho 0 02 0 23 Pb 208 0 05 He Ho 0 03 0 36 Quality control The quality control used for the new FGD wastewater method was based on the typical protocols used in other EPA methods Prior to commissioning for routine operation initial method validation requires determination of method detection limits linear ranges and analysis of multiple single element interference check solutions to assess the effectiveness of polyatomic interference removal under the collision reaction cell conditions used in the method In routine use daily quality control in a typical analytical sequence includes the analyses outlined in Table 3 The new FGD wastewater method requires the analysis of two new QC samples a Synthetic FGD Matrix Sample and a Fortified FGD Matrix Sample Prior to preparing the synthetic FGD matrix samples each potential matrix component was analyzed as a separate single element standard in order to determine the source and magnitude of any potential contaminants and the effectiveness of He mode at removing matrix based interferences Results are shown in Table 4 Nearly all contaminants and interferences were sub ppb The mos
6. boratory Control Sample MS MSD Matrix Spike Matrix Spike Duplicate Analytical Sequence Warm up Tune instrument Perform mass calibration check Perform resolution check Validate tuning criteria Calibration blank Calibration standard 1 Calibration standard 2 S D Calibration standard 3 n ICV a ICB o Method Reagent Blank Synthetic FGD Matrix Interference Check Laboratory Fortified Synthetic FGD Matrix Reporting Limit verification standard CCV CCB 10 Samples which can include all sample types Must include 1 LCS and 1 MS MSD pair CCV CCB Table 4 Initial demonstration of interference removal in single element matrix solutions Analyte concentrations ppb for each matrix sum of analyte impurity and residual spectral interference Mass Analyte 10 000 ppm Ca 10 000 ppmS 10 HCI 2 HNO 51 V 0 631 0 236 1 934 52 Cr 0 771 0 000 0 171 55 Mn 0 019 0 137 0 647 60 Ni 1 115 0 740 0 078 63 Cu 0 095 0 187 0 178 66 Zn 2 706 0 160 0 126 75 As 0 689 0 154 0 271 78 Se 0 029 0 213 0 320 107 Ag 0 012 0 040 0 002 111 Cd 0 005 0 031 0 044 121 Sb 0 656 0 028 0 542 205 TI 0 062 0 013 0 003 208 Pb 0 058 0 135 0 037 Table 5 Composition of Synthetic FGD Matrix Sample Laboratory Fortified Synthetic FGD Sample is spiked with 40 ppb of each of the target elements 400 ppb for zinc and 4000 ppb for aluminum Matrix component Concentration Chloride 5000 mg L Calcium 2000 mg L Mag
7. ision mode eliminates matrix based polyatomic interferences regardless of sample composition without the need for time consuming sample specific or analyte specific optimization The optional ISIS DS discrete sampling system significantly reduces run time while further reducing both matrix exposure and carryover Sample preparation The samples were collected in HDPE containers and acidified with trace metal grade nitric acid to pH lt 2 Sample preparation was performed according to EPA 1638 Section 12 2 for total recoverable analytes by digestion with nitric and hydrochloric acid in a covered Griffin beaker on a hot plate All calibrations were prepared in 2 HNO3 0 5 HCI v v as described in the method Analytical method A standard Agilent 7700x ICP MS with Micromist nebulizer and optional ISIS DS was used HMI aerosol dilution was set to medium using the MassHunter ICP MS software to automatically optimize the plasma parameters and robustness Ce0 Ce ratio 0 2 MassHunter uses HMI optimization algorithms that take into account the type of nebulizer used to ensure reproducible conditions from run to run and from instrument to instrument Operating parameters are shown in Table 1 Table 1 Instrument parameters used illustrating simple consistent instrument settings used for all analytes and all sample matrices Parameter Helium Mode Hydrogen Mode Instrument conditions HMI mode Robust plasma medium aerosol di
8. l limits 60 125 are indicated by red dashed lines Table 7 Matrix spike MS and matrix spike duplicate MSD results and relative percent differences RPD for the seguence of 88 analyses Spike concentration 20 ppb except silver which was 5 ppb Element Spike 1 Spike Duplicate RPD Spike 2 Spike Duplicate RPD Spike 3 Spike Duplicate RPD 78 Se 21 60 22 05 2 1 8425 29 8478 66 0 6 1927 89 1948 11 1 0 51 V 21 93 21 65 1 3 493 85 501 30 1 5 25 07 24 92 0 6 52 Cr 20 04 20 62 2 9 506 40 518 59 2 4 20 26 20 32 0 3 55 Mn 148 52 151 49 2 0 34308 04 34217 28 0 3 33316 73 33152 16 0 5 60 Ni 18 25 18 90 3 6 674 91 679 58 0 7 486 75 489 42 0 5 63 Cu 17 97 19 28 7 3 537 18 545 67 1 6 33 96 34 80 2 5 66 Zn 19 66 20 96 6 6 666 47 675 99 1 4 69 48 66 64 4 1 75 As 23 74 21 64 8 8 97 51 95 70 1 9 26 40 25 67 2 8 107 Ag 19 67 19 75 0 4 2 58 2 52 2 7 4 97 9 97 100 5 111 Cd 20 58 19 31 6 1 23 73 24 12 1 6 19 93 21 46 1 1 121 Sb 20 51 20 32 0 9 52 84 51 56 2 4 22 79 23 79 4 4 205 TI 20 24 20 07 0 8 20 68 20 25 2 1 24 87 25 82 3 8 208 Pb 19 79 20 14 1 8 150 09 150 06 0 0 20 27 19 74 2 6 Element Spike 4 Spike Duplicate RPD Spike 5 Spike Duplicate RPD Spike 6 Spike Duplicate RPD 78 Se 1056 43 1064 35 0 8 1038 18 1049 50 1 1 1100 59 1076 18 2 2 51 V 21 43 21 99 2 6 22 20 21 85 1 6 21 31 22 08 3 6 52 Cr 20 08 20 19 0 5 20 95 19 55 6 7 20 44 20 15 1 4 55 Mn 5093 08 5097 50
9. lution Forward RF power W 1550 Carrier gas flow L min 0 56 Dilution gas flow L min 0 33 Extraction lens 1 V 0 Kinetic energy 4 discrimination V Cell gas flow mL min 4 He 4 H2 Acguisition conditions Number of isotopes inc 25 3 ISTDs Number of replicates Total acquisition time sec ISIS parameters Sample loop volume uL Online dilution factor 80 total for both ORS modes 600 1 2 The ORS was operated in two modes helium collision mode He mode for all analytes except Se which was measured in hydrogen reaction mode H2 mode Twenty five masses including internal standards were acquired with typical integration times of 50 ms per replicate and three replicates per sample Instrument detection limits IDL were automatically calculated by the MassHunter software based on the precision of the calibration blank measurement and the slope of the calibration plots Table 2 Method detection limits MDL 30 were calculated from 7 replicate analyses of a low level spike of the synthetic FGD matrix solution Table 2 Analytes and analytical figures of merit MDL calculated as 35 of low level spike into synthetic FGD matrix sample n 7 MDL not calculated for chromium due to significant contamination in the synthetic FGD matrix solution Additional isotopes were acquired for internal confirmation but not reported Element Mass Int ORS ISTD IDL 3 sigma time Mode ppb MDL sec ng L
10. lyatomic ions Furthermore FGD wastewater can vary significantly from plant to plant depending on the type and capacity of the boiler and scrubber the type of FGD process used and the composition of the coal limestone and make up water used As a result FGD wastewater represents the most challenging of samples for ICP MS it is very high in elements known to cause matrix interferences and also highly variable To address this difficult analytical challenge in 2009 the EPA commissioned the development of a new ICP MS method specifically for FGD wastewaters This method was developed and validated at TestAmerica Laboratories Inc using an Agilent 7700x ICP MS equipped with an Agilent ISIS DS discrete sampling system Methods and materials Instrumentation The Agilent 7700x ICP MS with ISIS DS is uniquely suited to the challenge of developing a simple robust analytical method for the analysis of regulated metals in uncharacterized high matrix FGD wastewaters Three attributes of the 7700x system are particularly critical and work together to enable reliable routine analysis of large batches of variable high matrix samples Agilent s unique High Matrix Introduction HMI system enables controlled reproducible aerosol dilution which increases plasma robustness and significantly reduces exposure of the interface and ion lenses to undissociated sample matrix The Octopole Reaction System ORS operating in helium coll
11. nal CCV sample In the complete sequence a total of six MS MSD pairs were analyzed and the relative percent difference RPD calculated for each pair is shown in Table 7 The method limit for RPD is lt 20 which includes both measurement and sample prep errors Only silver proved to be problematic late in the sequence most likely due to chemical stability solubility problems in samples containing high and variable levels of chloride CPS Recovery I 72 ce 1 I 165 Ho 2 118 In 2 IE 115 In 2 E 72 ce 2 E 45 Sc 2 150 N NNN NNN N NNN NN NNN OQ N NNN OQ NNN SS 9088888883082 80388 8 8 30883 58888 D 88888 D OG 2 2 P Zypo 9 9 3 wo P 2 33 3 5 9 uv 2 39 9 P 3 v 9 9 5 o 9 2 USEZEN 5 0 dn A A A i D A A A D K A A Tv A A OM A A A mh A k pA kA v 53 o MN ww M O OD OD N 80 o o 0 N NB O O SNN N Yuuh o o 23 38 5 LS 3 4 34 3 4 OS G HHT 0 88 A AR O P 8 A R 90 o o q 58 93 2 IEEE BTTr S 8 D PD gt PA nn dan Non n na ATA RAAT onononan D nn h S g DS SN b KA PR LZ pS aa LL 5 O DB LAN a a D D D D D D D S D PY P One eR Oa RY a v 1 AT TT o VY NI PP D a x s mono gt 0 gt z 0 m o 9 XY gt TE BG S see S D o v o o Z T 3 28858 3838 RERBS Dis Por SEER SSBB o 8 y ey a O 0 o ka Figure 2 Internal standard recoveries for entire 88 sample seguence Contro
12. nesium 1000 mg L Sulfate 2000 mg L Sodium 1000 mg L Butanol 2 mL L Table 6 Analysis of mixed matrix FGD interference check sample and spiked FGD matrix solution CCV expected value 50 ppb Cr contamination verified by secondary isotope Mass FGD Fortified Carryover CCV CCB Analyte Matrix FGD Check ppb ppb Check Recovery 51 V 0 187 102 2 0 068 48 885 0 101 52 Cr 12 699 96 6 0 015 48 851 0 117 55 Mn 0 101 94 3 0 328 48 435 0 100 60 Ni 0 247 88 4 0 009 48 535 0 154 63 Cu 0 094 91 6 0 096 47 316 0 115 66 Zn 3 181 86 1 0 302 49 804 0 100 75 As 0 107 110 0 0 043 48 205 0 009 78 Se 0 538 120 2 0 144 49 605 0 186 107 Ag 0 145 94 3 0 010 47 632 0 003 111 Cd 0 039 98 9 0 017 48 695 0 017 121 Sb 0 181 98 4 0 015 50 806 0 031 205 TI 0 021 90 3 0 000 48 108 0 008 208 Pb 0 436 92 1 0 003 48 381 0 008 Results Initial performance verification indicated that the 7700x with HMI was able to analyze the very high matrix samples and He mode successfully eliminated matrix based spectroscopic interferences while the use of ISIS DS helped to minimize memory effects Table 6 Accuracy both in terms of calibration stability CCV and for spike recoveries in the matrix spiked FGD solution were well within the standard operating procedure SOP requirements CCV 15 Matrix Spike Recoveries 30 When running real FGD samples in a long sequence continuing instrument performance must be monitored according
13. t significant contaminants were Cr Ni and Zn in the 10 000 ppm Ca solution confirmed by measuring secondary or qualifier isotopes for the analytes Approximately 2 ppb of V was detected in the 10 HCI solution This was either due to contamination a small residual interference from 35C1160 or a combination of the two but at less than 2 ppb it did not present a problem for this analysis After each matrix component was characterized individually a mixed synthetic FGD solution was prepared with the composition shown in Table 5 together with a second solution with the same matrix components but additionally spiked with all the analyte elements at 40 ppb These new FGD matrix samples are analogous to the interference check solutions ICS A and ICS AB required by EPA method 6020 except the synthetic FGD samples are much higher in total dissolved solids TDS than the ICS A and AB solutions and contain those matrix elements that are commonly high in actual FGD samples The detailed composition of the FGD Matrix Samples which contain a total of gt 1 10 000 ppm TDS is listed in Table 5 and results from the analysis of the synthetic FGD matrix blank and synthetic FGD matrix spike are shown in Table 6 Table 3 Typical FGD analytical sequence including all required quality control ICV Initial Calibration Verification ICB Initial Calibration Blank CCV Continuing Calibration Verification CCB Continuing Calibration Blank LCS La

Agilent Analysis of flue gas desulfurization wastewaters by Agilent 7700x ICP-MS Manual

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