a p p l i c at i o n N o t e ICP-OES Authors Paul Krampitz Stan Smith PerkinElmer, Inc. Shelton, CT 06484 USA Increased Laboratory Productivity for ICPOES Applied to U.S. EPA Method 6010C Abstract The use of an ESI SC FAST autosampler coupled to a Perkin Elmer Optima 7300 DV ICP can dramatically improve productivity for the analysis of environmental samples using EPA SW-846 Method 6010C. Sample throughput, as determined by sample-to-sample run time can be improved by as much as 100% as compared to traditional sample introduction systems and autosampler configurations. Both sample analysis time and rinse out time are significantly reduced, allowing for a doubling of overall productivity. In addition, stability of the plasma and instrument is very robust allowing for long, unattended run times while meeting calibration and method QC requirements. Valuable man hours spent on instrument maintenance and recalibration are reduced. This paper will demonstrate that these productivity enhancement claims can be accomplished for implementation SW-846 Method 6010C. Introduction Since 1980, the EPA has maintained a publication entitled SW-846 Test Methods for Evaluating Solid Waste, Physical/ Chemical Methods, more commonly referred to simply as SW-846. Currently, SW-846 is in its third edition and includes several updates. Since the third edition was released in 1986, there have been 9 updates (Updates I, II, IIA, IIB, III, IIIA, IIIB, IVA, and IVB), the most recent of which was dated February, 2007. Included in SW-846 are over 200 documents related to quality control practices, analytical test methods, sampling methods, and other topics related to the United States Environmental Protection Agency (EPA) Resource Conservation and Recovery Act (RCRA). Essentially, SW-846 is the official compendium of analytical and sampling methods that have been evaluated and approved by the EPA for use in complying with RCRA regulations. As indicated by the EPA, the analytical methods in SW-846 are intended to be guidance documents and are not intended to be overly prescriptive except in the cases where a particular analyte or parameter is considered method defined. Such method-defined parameters are where the analytical result is wholly dependent on the process and conditions of the test or preparation method such as the Toxicity Characteristic Leaching Procedure (TCLP), Method 1311, where the conditions specified in the method directly affect the concentration of analytes extracted into the leaching solution. However, despite this clear indication from the EPA that SW-846 methods are intended as guidance documents, many regulatory agencies invoke these methods with no permissible changes or modifications. The analytical test methods found in SW-846 are commonly used by laboratories for the analysis of a wide range of sample matrices including, but not limited to: groundwater, surface water, leachates, soils, and a whole host of other solid and liquid wastes, both organic and aqueous. The RCRA regulatory programs for which SW-846 is most commonly used can be found in the U.S. Code of Federal Regulations (CFR), specifically Title 40 CFR Parts 122-270. One of the methods found in SW-846 that is commonly used by most environmental laboratories for the analyses of elements in environmental samples is 6010C Inductively Coupled Plasma-Atomic Emission Spectrometry (ICP-AES). Method 6010C is the fourth version of this method and was released as part of SW-846 Update IV in February, 2007. As indicated in the method, all samples other than filtered, preserved groundwaters require acid digestion prior to analysis. There are more than 8 acid digestion methods applicable to ICP-AES found in SW-846 and some of those that are commonly used for the preparation of environmental samples include: • 3005A Acid Digestion of Waters for Total Recoverable or Dissolved Metals for Analysis by FLAA or ICP Spectroscopy • 3010A Acid Digestion of Aqueous Samples and Extracts for Total Metals for Analysis by FLAA or ICP Spectroscopy • 3015A Microwave Assisted Acid Digestion of Aqueous Samples and Extracts • 3050B Acid Digestion of Sediments, Sludges, and Soils • 3051A Microwave Assisted Acid Digestion of Sediments, Sludges, Soils, and Oils Summary of Method Figure 1. Schematic of FAST sample introduction system coupled to an Optima 7300 DV ICP spectrometer. 2 Method 6010C is a general analytical method that is applicable to a wide variety of liquid and solid samples and that provides specific procedures and references for sample collection, preservation, and preparation (i.e., acid digestion), in addition to recommended instrument procedures for calibration, detection limits, and interference correction. In addition, SW-846 6010C also contains procedures for the preparation, analysis, and acceptance limits for quality control samples needed for each batch of samples to be analyzed. While the method is intended only as a guidance document and is subject to interpretation and modification, implementation of the QC criteria as stated in the method was followed for the work performed and summarized in this paper. The EPA has approved this method for the analysis of 31 elements and Table I includes all the elements analyzed and their associated wavelengths. Following is a summary of the procedure from SW-846 6010C as performed in this work. Table I. Wavelengths Monitored and Viewing Modes Used for SW-846 6010C. Summary of Method 6010C Establish Initial Demonstration of Performance Wavelength Analyte Symbol Monitored (nm) View 2. Determine Linear Dynamic Range (LDR) Aluminum Al 308.215 Radial Antimony Sb 206.836 Axial a. Recovery of elements must be ±10% of the known values for each element Arsenic As 188.979 Axial 3. Determine whether interelement corrections are needed by Barium Ba 233.527 Axial Beryllium Be 234.861 Radial Routine Analysis Boron B 249.677 Radial Cadmium Cd 226.502 Axial 1. Light plasma and warm up instrument, allow 15-30 minutes Calcium Ca 315.887 Radial Chromium Cr 267.716 Axial Cobalt Co 228.616 Axial Copper Cu 327.393 Axial Iron Fe 238.204 Radial Lead Pb 220.353 Axial Lithium Li 670.784 Radial 4. Verify calibration by analyzing the Initial Calibration Verification (ICV) standard Magnesium Mg 285.213 Radial Manganese Mn 257.610 Axial a. ICV standard must be from a separate source as used for calibration standards Molybdenum Mo 202.035 Axial Nickel Ni 231.604 Axial b. Recovery of elements must be ±10% of the known values for each element Phosphorus P 213.617 Axial 5. Verify the lowest quantification limit by analyzing the Lower Limit of Quantitation Check Sample (LLQC) Potassium K 766.490 Radial Selenium Se 196.026 Axial a. LLQC standard should be from the same source as the calibration standards Silicon Si 251.611 Radial Silver Ag 328.068 Axial b. Recovery of elements must be ±30% of the known values for each element Sodium Na 589.592 Radial Strontium Sr 407.771 Radial Thallium Tl 190.801 Axial Tin Sn 189.927 Axial Titanium Ti 334.940 Axial Vanadium V 292.402 Axial 8. After every 10 samples, verify calibration by analyzing the Continuing Calibration Verification (CCV) standard Zinc Zn 206.200 Axial a. CCV standard should be from the same source as the calibration standards Yttrium Y 371.029 Radial/Axial b. Recovery of elements must be ±10% of the known values for each element Tellurium Te 214.281 Radial/Axial 1. Perform Instrument Detection Limits (IDL) Internal Standards analysis of an Interference Check Solution (ICS) 2. Optimize instrument and plasma conditions per instrument manufacturer 3. Calibrate ICP using blank and minimum of one standard a. Rinse with blank between each standard b. Use the average of multiple readings (3 replicates in this study) for all standards and samples 6. Analyze the Initial Calibration Blank (ICB) a. Target elements should not be detected at or above the Lower Limit of Quantitation 7. Analyze test samples along with appropriate batch quality control samples 9. Immediately following the analysis of each CCV, analyze the Continuing Calibration Blank (CCB) a. Target elements should not be detected at or above the Lower Limit of Quantitation 10. The LLCCV must be analyzed at the end of each analytical batch but is also recommended to be analyzed after every 10 samples a. Recovery of elements must be ±30% of the known values for each element 11. At the end of the run, analyze the CCV and CCB a. Acceptance limits are the same as in steps 8 and 9 3 Batch Quality Control Samples 1. Analyze the Method Blank a. Target elements should not be detected at or above 10% of the Lower Limit of Quantitation 2. Analyze the Laboratory Control Sample (LCS) a. Recovery of elements must be ±20% of the spiked values for each element 3. Analyze the Matrix Spike a. Recovery of elements must be ±25% of the spiked values for each element 4. Analyze the Sample Duplicate or Matrix Spike Duplicate a. The precision criterion for duplicates is a relative percent difference of no greater than 20% Experimental Initial Performance Demonstration Instrument Detection Limits The Instrument Detection Limits (IDL) for all elements were determined using a reagent blank solution according the procedures in Section 9.3 of SW-846 6010C. Specifically, a reagent blank was analyzed seven consecutive times, with routine rinsing procedures between each analysis, for all elements three times on non-consecutive days. The IDLs were then estimated by calculating the average of each element’s standard deviation. The obtained IDLs are presented in Table III. Evaluation of Interferences Interferences were evaluated according to Section 4.2.10 of Method 6010C. An interference check solution containing 500 mg/L of Al, Ca, Mg, Na, 200 mg/L of Fe and 50 mg/L of K was used for evaluation. Instrument An Optima 7300 DV (PerkinElmer, Shelton, CT) was used in conjunction with an SC-FAST (Elemental Scientific Inc., Omaha, NE) for the analysis of all samples described in this work. The FAST sample introduction system is controlled through the Optima WinLab32™ software and a schematic of the FAST is shown in Figure 1. The elements, wavelengths, and plasma viewing modes used are listed in Table I. The instrument conditions for both the Optima ICP-OES and the SC-FAST as well as the experimental parameters used are provided in Table II. Experimental Parameters. Optima 7300 DV Parameters RF Power 1450 watts Plasma Gas Flow 15 L/min Auxiliary Gas Flow 0.2 L/min Nebulizer Gas Flow 0.6 L/min Peristaltic Pump Speed 0.85 mL/min Nebulizer/Spray Chamber Sea Spray/Glass cyclonic Torch Cassette Position -3 Standards Purge Normal All calibration standards and non-sample solutions were prepared with ASTM Type I (i.e., >18MΩ-cm) deionized water and trace metals grade or better nitric acid. Resolution Normal Integration Time 2 s min/5 s max Read Delay 14 s Wash Time 1s Number of Replicates 3 Internal Standards All samples were spiked with 1.5 mg/L of yttrium and 2.5 mg/L of tellurium. The spiking solution was made from 1000 mg/L single element stock solutions. FAST Parameters Calibration The calibration blank and standards were prepared in 1% nitric acid. Calibration was performed using a calibration blank and a single standard containing all elements at 1 mg/L. The calibration standard was prepared from a combination of single element and multi-element stock solutions, all containing elements at 1000 mg/L. Monitored Wavelengths As previously mentioned, the monitored elements, wavelengths, and plasma viewing modes used are listed in Table I. 4 Table II. FAST-Optima 7300 DV Instrumental Conditions and Sample Loop Volume 2 mL Sample Loop Fill Rate 27 mL/min Carrier Pump Tubing Black/Black (0.76 mm i.d.) Sample Load Time 7s Rinse 1s Analysis Time (total) 75 s (sample-to-sample) Experimental Parameters Carrier Solution 1% HNO3 plus 0.05% surfactant Rinse Solution 1% HNO3 Acidity of Stds/Samples 1% HNO3 Table III. Instrument Detection Limit (IDL) Data and Linear Dynamic Ranges (LDR). Analyte Wavelength IDL IDL IDL 6010C, LDR, RUN 1 RUN 2 RUN 3 IDL, ug/L mg/L Ag 0.159 0.103 0.172 0.14 100 328.068 Al 308.215 1.732 0.630 1.898 1.42 2000 As 188.979 0.349 0.415 0.774 0.51 100 B 249.677 4.504 1.400 1.109 2.34 2000 Ba 233.527 0.056 0.016 0.034 0.04 25 Be 234.861 0.034 0.018 0.075 0.04 50 Ca 317.933 0.544 0.550 0.783 0.63 900 Cd 226.502 0.041 0.037 0.073 0.05 100 Co 228.616 0.076 0.092 0.078 0.08 250 Cr 267.716 0.086 0.099 0.071 0.09 100 Cu 327.393 0.062 0.047 0.158 0.09 300 Linear Range The Linear Dynamic Range (LDR) was determined for each element and met the criterion in Section 10.4 of SW-846 6010C as found in Table III. That is, the upper linear range was established by analyzing standards against the same calibration used for analyzing samples and obtaining recoveries within ±10% of the known concentration value. The Lower Limit of Quantitation was confirmed through the analysis of the Lower Level Check Standard (LLICV and LLCCV) and obtaining recoveries within ±30% of the known concentration value. The LLICV and LLCCV were run at a concentration of 500 ug/L for this study. Fe 259.939 0.256 0.230 0.168 0.22 400 K 766.49 7.269 5.270 5.499 6.01(0.24) 2000 Mg 279.077 1.763 2.030 3.108 2.30 700 Memory Effects Mn 257.61 0.005 0.009 0.018 0.01 40 Memory effect studies were performed to obtain the rinse time needed between sample measurements using the ESI FAST system. The elements studied were the most likely elements to be high for environmental samples run under SW 846: Al, Ca, Fe, K, Mg, and Na. All of the data can be found in Figure 2. Five blanks were run, then five standards, then five blanks again to obtain the rinse out profiles. Al, Ca, Mg, and Na were run at 500 mg/L. Fe was run at 200 mg/L and K was run at 50 mg/L. The FAST parameters used were the same as listed in Table II above. Mo 202.031 0.132 0.097 0.180 0.14 125 Na 589.592 1.147 2.364 1.609 1.71(0.2) 900 Ni 231.604 0.178 0.188 0.161 0.18 125 Pb 220.353 0.427 0.229 0.368 0.34 100 P 213.617 1.543 1.091 1.249 1.29 3000 Li 670.784 0.214 0.176 0.364 0.25(0.03) 200 Sb 206.836 0.662 0.586 0.226 0.49 100 Se 196.026 0.875 0.953 0.485 0.77 100 Si 251.611 2.546 0.569 1.080 1.40 2500 Sr 421.552 0.025 0.029 1.139 0.40(0.01) 50 Sn 189.927 1.928 1.218 0.095 1.08(0.35) 2000 Ti 334.94 0.017 0.018 1.863 0.63 50 Tl 190.801 0.574 0.568 0.114 0.42 100 V 292.402 0.070 0.059 0.781 0.30 50 Zn 206.2 0.051 0.039 0.086 0.06 100 ( ) = Axial 5 Figure 2. Above figures show the rinse out time using the ESI FAST system. Al, Ca, Mg, and Na were run at 500 mg/L. Fe was run at 200 mg/L and K was run at 50 mg/L. Samples were rinsed out to near baseline in 7 seconds. Quality Control and Sample Analysis The accuracy and precision of the implementation of Method 6010C was demonstrated through the analysis of several reference materials and a local filtered, treated surface water sample (Lake Michigan). The quality control procedures specified in SW-846 were followed throughout the work performed. Immediately following calibration, the ICV (second source), LLICV, and ICB were analyzed and all results were determined to be within method-specified criteria, ±10%, ±30%, and <LLQC respectively. Following the analysis of each sequence of ten samples, the CCV, LLCCV, and CCB were analyzed and found to be within the method-specified criteria (same as for ICV, LLICV, and ICB). In additional to the sequential run QC (10% frequency), batch QC samples were also prepared and analyzed. As all 6 samples analyzed were synthetic or natural water samples with no detectable turbidity or suspended solids, no acid digestion procedures were performed. The batch QC consisted of a method blank, a sample duplicate (DUP), a Laboratory Control Sample (LCS), a Matrix Spike (MS), and a Matrix Spike Duplicate (MSD). A natural surface water sample was used to prepare the DUP, MS, and MSD. Results of all batch QC samples were found to be within method-specified criteria. That is, no elements were detected within 10% of the LLQC, all elements detected in the sample and the sample DUP above the LLQC had relative percent differences of less than 20, all elements in the LCS were recovered within 20% of the known spike concentration, all elements in both the MS and MSD recovered within 25% of the known spike concentration, and all spiked elements in the MS and MSD had relative percent differences of less than 20. Figure 3. Four hour CCV stability. Table IV. NIST 1640 Trace Elements in Natural Water. Run 1 Run 2 Average Certified mg/L units % REC. Ag 328.068 0.007683478 0.007578301 0.00763089 0.0076 100 As 188.979 0.027794979 0.027058423 0.027426701 0.027 102 In addition to the batch QC samples, several reference materials were analyzed and included two Standard Reference Materials® (SRM) from the National Institute of Standards & Technology (NIST), one Certified Reference Material (CRM) from the National Research Council Canada (NRCC), and two commercially available water Proficiency Test (PT) samples. The NIST samples included SRM 1643e Trace Elements in Water and SRM 1640 Trace Elements in Natural Water. The NRCC sample was SLRS-4 River Water Reference Material for Trace Metals. This CRM is typically used for ICP-MS instrumentation due to the low concentrations of elements, however, it has been included to show the excellent sensitivity of the Optima 7300 DV. The two commercial PT samples included WP Trace Metals and WS Trace Metals. Results of all five reference materials are presented in Table IV – Table VIII. B 249.677 0.321778774 0.31648758 0.319133177 0.3 106 Stability Ba 233.527 0.148039192 0.146252596 0.147145894 0.148 99 Ca 317.933 7.287467245 7.29179424 7.289630743 7.045 103 Cd 226.502 0.02461 0.024202 0.024406 0.0228 107 The Continuing Calibration Verification (CCV) standard was analyzed repeatedly throughout each analytical run and no less frequently than after every 10 samples. The recoveries for each of the CCVs obtained have been plotted against time for a period of four hours. The results are shown in Figure 3. All 30 elements monitored in this study were well within the method-specified acceptance criterion of ±10% of the known value. Typical drift for most elements was less than 3%. Co 228.616 0.022373993 0.022173326 0.02227366 0.022 101 Cr 267.716 0.041212275 0.040675621 0.040943948 0.0386 106 Cu 327.393 0.090707058 0.088824718 0.089765888 0.0852 105 Fe 259.939 0.034529324 0.033692193 0.034110759 0.0343 99 K 766.490 1.015084221 1.007176206 1.011130214 0.994 102 Mg 279.077 5.648166692 5.633282915 5.640724804 5.819 97 Mn 257.610 0.124362054 0.122821057 0.123591555 0.1215 102 Mo 202.031 0.049788978 0.049545748 0.049667363 0.04675 106 Na 589.592 29.22808031 28.92173556 29.07490794 29.35 99 Ni 231.604 0.029560106 0.029416086 0.029488096 0.0274 108 Pb 220.353 0.027413987 0.027680616 0.027547302 0.02789 99 Li 670.784 0.05139438 0.050218507 0.050806444 0.0507 100 Se 196.026 0.023501 0.023504 0.0235025 0.022 107 Si 251.611 4.747666191 4.644475617 4.696070904 4.73 99 Sr 421.552 0.12522384 0.125293217 0.125258528 0.124 101 V 292.402 0.013012505 0.012822827 0.012917666 0.013 99 Zn 206.200 0.057402 0.056602 0.057002 0.0532 107 Be 234.861 0.036510499 0.036158461 0.03633448 0.035 104 Data Handling All data obtained from the Optima 7300 DV was collected using the WinLab32 software loaded on a desktop PC attached to the instrument. Analytical results were computed using the WinLab32 software and exported into Microsoft® Excel®. The text and data tables used in this report were created using Microsoft® Excel® and Word. 7 8 Table V. NIST 1643e Trace Elements in Water. Run 1 Run 2 Average Certified mg/L units % REC. Ag 328.068 0.00082799 0.000982703 0.000905346 0.001 Al 308.215 0.14958319 0.145968533 0.147775861 0.142 Table VI. National Reasearch Council Canada 91 Riverine Water. Run 1 Certified mg/L units % REC. 104 Ca 317.933 6.088272145 6.2 98 As 188.979 0.05863297 0.060202348 0.059417659 0.0605 98 Fe 259.939 0.108512603 0.103 105 Ba 233.527 0.526201428 0.53185025 0.529025839 0.544 97 K 766.490 0.671190352 0.68 99 Ca 317.933 31.36350994 31.38490986 31.3742099 32.3 97 Mg 279.077 1.544935545 1.6 97 Cd 226.502 0.006803606 0.006802601 0.006803103 0.00657 104 Na 589.592 2.189781306 2.4 91 Co 228.616 0.027229571 0.027465911 0.027347741 0.02706 101 Sn 189.927 0.028264829 0.0263 107 Cr 267.716 0.021901845 0.021954832 0.021928339 0.0204 107 K 766.490 0.000887947 0.00093 95 Cu 327.393 0.022717423 0.022755897 0.02273666 0.02276 100 Mg 279.077 0.661790584 0.68 97 Fe 259.939 0.09995466 0.10046584 0.10021025 0.0981 102 Na 589.592 1.660975302 1.6 104 2.193887808 2.4 91 0.058305976 0.054 108 K 766.490 2.115235445 2.134464228 2.124849837 2.034 104 Li 670.784 Mg 279.077 7.594261315 7.676997678 7.635629497 8.037 95 Be 234.861 Mn 257.610 0.036795431 0.037161031 0.036978231 0.03897 95 Mo 202.031 0.127822547 0.128341294 0.128081921 0.1214 106 Na 589.592 19.36434423 19.37433937 19.3693418 20.74 93 Ni 231.604 0.062047849 0.062322707 0.062185278 0.0624 100 Pb 220.353 0.017716846 0.018946104 0.018331475 0.01963 93 Li 670.784 0.018412973 0.018762553 0.018587763 0.0174 107 Sb 206.836 0.056414629 0.057170312 0.05679247 0.0583 97 Se 196.026 0.011186647 0.012221246 0.011703946 0.01197 98 Sr 421.552 0.313265799 0.31293833 0.313102065 0.323 97 Tl 190.801 0.006104 0.00703 0.006567 0.007445 88 V 292.402 0.036212595 0.036634849 0.036423722 0.03786 96 Zn 206.200 0.074767001 0.075143809 0.074955405 0.0785 95 Be 234.861 0.014348862 0.014500296 0.014424579 0.014 103 Table VII. WP Trace Metals. Run 1 Run 2 Average Conclusion Certified mg/L units % REC. Ag 328.068 0.415039553 0.415691157 0.415365355 0.4 104 Al 308.215 2.161214156 2.178741769 2.169977963 2.25 96 As 188.979 0.206215282 0.211098072 0.208656677 0.198 105 Be 313.107 0.104177959 0.104164917 0.104171438 0.107 97 Cd 226.502 0.162228771 0.162383871 0.162306321 0.162 100 Co 228.616 0.596703569 0.596119333 0.596411451 0.575 104 Cr 267.716 0.172615602 0.172950538 0.17278307 0.162 107 Cu 327.393 0.405182422 0.405208121 0.405195272 0.378 107 Fe 259.939 1.392941099 1.392462656 1.392701878 1.41 99 Mn 257.610 1.925099213 1.927471996 1.926285605 1.95 99 Ni 231.604 0.325614799 0.326326585 0.325970692 0.317 103 Pb 220.353 0.475584088 0.478602286 0.477093187 0.496 96 Se 196.026 0.752168839 0.766870842 0.75951984 0.721 105 Sr 421.552 0.122143791 0.122530301 0.122337046 0.122 100 Tl 190.801 0.65022971 0.657954117 0.654091913 0.633 103 V 292.402 1.122841516 1.12365243 1.123246973 1.13 99 Zn 206.200 0.610901508 0.611869781 0.611385645 0.613 100 Be 234.861 0.101283259 0.101227224 0.101255241 0.107 95 Table VIII. WS Trace Metals. Run 1 Run 2 Average The FAST system coupled with the Optima 7300 DV has been shown to produce results that meet the requirements outlined in U.S. EPA Method SW-846 while doubling sample productivity when compared to analyses with conventional introduction systems. Since the FAST system eliminates virtually all of the rinse and read delay times, most of the time is now spent running samples, therefore increasing productivity. The user will also have much less torch and injector maintenance since the system will see the sample matrix for a much shorter period of time. Also, since the FAST reaches a steady state signal much more quickly than conventional sample introduction, instrument detection limits are improved almost 2-fold for many analytes. Consequently, the Optima 7300 DV when used in conjunction with the SC-FAST autosampler provides a rugged, automated sample introduction system that can significantly reduce labor costs and improve laboratory productivity. Certified mg/L units % REC. Ag 328.068 0.205841482 0.206784064 0.206312773 0.201 103 Al 308.215 1.503360942 1.509021475 1.506191209 1.5 100 As 188.979 0.04707919 0.048926848 0.048003019 0.0485 99 Ba 233.527 0.67227925 0.67399818 0.673138715 0.647 104 Be 313.107 0.009084418 0.009042679 0.009063548 0.0087 104 Cd 226.502 0.00998403 0.01004741 0.01001572 0.00927 108 Cr 267.716 0.136730412 0.137652362 0.137191387 0.132 104 Cu 327.393 0.715153403 0.720991073 0.718072238 0.677 106 Fe 259.939 0.913585704 0.915318141 0.914451923 0.93 98 Mn 257.610 0.358912563 0.357960513 0.358436538 0.366 98 Mo 202.031 0.043977706 0.044482171 0.044229939 0.0437 101 Ni 231.604 0.109153638 0.109458221 0.109305929 0.107 102 Pb 220.353 0.068196964 0.06857344 0.068385202 0.0668 102 Sb 206.836 0.043471699 0.042509311 0.042990505 0.0432 100 Se 196.026 0.074839851 0.074040603 0.074440227 0.0747 100 Tl 190.801 0.006336361 0.006970729 0.006653545 0.00717 93 V 292.402 0.480020599 0.481743476 0.480882038 0.456 105 Zn 206.200 0.712322194 0.711716612 0.712019403 0.706 101 PerkinElmer, Inc. 940 Winter Street Waltham, MA 02451 USA P: (800) 762-4000 or (+1) 203-925-4602 www.perkinelmer.com For a complete listing of our global offices, visit www.perkinelmer.com/ContactUs Copyright ©2009, PerkinElmer, Inc. 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