1、Designation:D680002 (Reapproved 2007)1Designation: D6800 12Standard Practice forPreparation of Water Samples Using Reductive PrecipitationPreconcentration Technique for ICP-MS Analysis of TraceMetals1This standard is issued under the fixed designation D6800; the number immediately following the desi
2、gnation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope Scope*1.1 Toxic elements may be p
3、resent in ambient waters and may enter the food chain via uptake by plants and animals; the actualconcentrations of toxic metals are usually sub-ng/mL. The U.S. EPA has published its Water Quality Standards in the U.S. FederalRegister 40 CFR 131.36, Minimum requirements for water quality standards s
4、ubmission, Ch. I (7-1-00 Edition), see Annex, TableA1.1. The U.S. EPA has also developed Method 1640 to meet these requirements, see Annex, Table A1.2.1.2 Inductively Coupled Plasma Mass Spectroscopy (ICP-MS) is a technique with sufficient sensitivity to routinely measuretoxic elements in ambient wa
5、ters, both fresh and saline (Test Method D5673). However saline and hard water matrices poseanalytical challenges for direct multielement analysis by ICP-MS at the required sub-ng/mL levels.1.3 This standard practice describes a method used to prepare water samples for subsequent multielement analys
6、is usingICP-MS. The practice is applicable to seawater and fresh water matrices, which may be filtered or digested. Samples prepared bythis method have been analyzed by ICP-MS for the elements listed in Annex, Table A1.3).1.41.4 The values stated in SI units are to be regarded as standard. No other
7、units of measurement are included in this standard.1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety and health practices and determine the applicability of r
8、egulatorylimitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D1129 Terminology Relating to WaterD1193 Specification for Reagent WaterD5673 Test Method for Elements in Water by Inductively Coupled PlasmaMass SpectrometryD5810D5810 Guide for Spiking into Aqueous SamplesD5847 Practice f
9、or Writing Quality Control Specifications for Standard Test Methods for Water Analysis2.2 Other Documents:U.S. Federal Register 40 CFR 131.36, Minimum Requirements for Water Quality Standards Submission, Ch. I (7-1-00 Edition)3U.S. EPA Method 1640, Determination of Trace Elements in Water by Preconc
10、entration and Inductively Coupled Plasma-MassSpectrometry (1997)4U.S. EPA Method 1669, Sampling Ambient Water for Trace Metals at EPA Water Quality Criteria Levels43. Terminology3.1 DefinitionsFor definitions of terms used in this test method refer to Terminology D1129.3.2 Definitions of Terms Speci
11、fic to This Standard:3.2.1 dissolvedthe concentration of elements determined on a filtered fraction of a sample. Samples are filtered through a 0.451This practice is under the jurisdiction of ASTM Committee D19 on Water and is the direct responsibility of Subcommittee D19.05 on Inorganic Constituent
12、s in Water.Current edition approved Aug.March 1, 2007.2012. Published September 2007.March 2012. Originally approved in 2002. Last previous edition approved in 20022007 asD6800 02(2007)e01. DOI: 10.1520/D6800-02R07E01.10.1520/D6800-12.2For referencedASTM standards, visit theASTM website, www.astm.or
13、g, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.3Available from DODSSP, Bldg. 4, Section D, 700 Robbins Ave., Philadelphia, PA 191115098.4Available from United States Environm
14、ental Protection Agency (EPA), Ariel Rios Bldg., 1200 Pennsylvania Ave., NW, Washington, DC 20460, http:/www.epa.gov.1This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Becauseit may
15、 not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current versionof the standard as published by ASTM is to be considered the official document.*A Summary of Changes section appears at the
16、 end of this standard.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.m membrane filter before acid preservation. intermediate stock-standard solution, na diluted solution prepared from one ormore of the stock-standard solutions.3.2.2
17、 intermediate stock standard solutiona diluted solution prepared from one or more of the stock standard solutions.laboratory control sample (LCS), nan aliquot of solution with known concentrations of method analytes.3.2.2.1 DiscussionThe LCS should be obtained from a reputable source or prepared at
18、the laboratory from a separate sourcefrom the calibration standards. The LCS is analyzed using the same sample preparation, analytical method and QA/QC procedureused for test samples. Its purpose is to determine whether method performance is within accepted control limits.3.2.3 laboratory control sa
19、mple (LCS)an aliquot of solution with known concentrations of method analytes. It should beobtained from a reputable source or prepared at the laboratory from a separate source from the calibration standards. The LCS isanalyzed using the same sample preparation, analytical method and QA/QC procedure
20、 used for test samples. Its purpose is todetermine whether method performance is within accepted control limits. laboratory duplicate (LD), na second sample aliquotthat is analyzed using the same sample preparation, analytical method and QA/QC procedure used for test samples.3.2.3.1 DiscussionThe pu
21、rpose of the LD is to determine whether method performance is within accepted control limits.3.2.4 laboratory duplicate (LD)a second aliquot of a sample should be analyzed using the same sample preparation, analyticalmethod and QA/QC procedure used for test samples. Its purpose is to determine wheth
22、er method performance is within acceptedcontrol limits.3.2.5matrix spike (MS)a second aliquot of a sample to which known concentrations of target analyte(s) are added in thelaboratory and should be analyzed using the same sample preparation and analytical method used for test samples. Its purpose is
23、to determine whether the sample matrix contributes bias to the analytical results. The background concentration of the matrix mustbe determined in a separate aliquot and the measured values in the MS corrected for the concentrations found. Recommended spikelevels are listed in Annex, matrix spike (M
24、S), na second sample aliquot to which known concentrations of target analyte(s) areadded in the laboratory and which are analyzed using the same sample preparation and analytical method used for test samples.3.2.4.1 DiscussionThe purpose of the MS is to determine whether the sample matrix contribute
25、s bias to the analytical results.The background concentration of the matrix must be determined in a separate aliquot and the measured values in the MS correctedfor the concentrations found. Recommended spike levels are listed in Annex, Table A1.3.3.2.5 method blank (MB), nsuitable reagent-water aliq
26、uots that are analyzed using the same sample preparation, analyticalmethod, and QA/QC procedure used for test samples.3.2.5.1 DiscussionThe MB is used to determine if method analytes or other interferences are present in the laboratoryenvironment, the reagents or apparatus.3.2.6 method blank (MB)sui
27、table aliquots of reagent water are analyzed using the same sample preparation technique,analytical method and QA/QC procedure used for test samples. The MB is used to determine if method analytes or otherinterferences are present in the laboratory environment, the reagents or apparatus. method dete
28、ction limit (MDL), na limitdetermined as described in the U.S. Federal Register (see 40 CFR Part 136, Appendix B).3.2.7 method detection limit (MDL)determined as described in the U.S. Federal Register (see 40 CFR Part 136, Appendix B).3.2.8reagent waterreagent water, nstandard laboratory water purif
29、ied to meet Specification D1193 Type I or better.3.2.8 reporting detection limit (RDL), nthe lowest concentration at which an analyte can be reliably quantified. .3.2.8.1 DiscussionThe RDL represents the minimum concentration at which method performance becomes quantitative andis not subject to the
30、degree of variation observed at concentrations between the MDL and the RDL3.2.9 reporting detection limit (RDL)the lowest concentration at which an analyte can be reliably quantified. The RDLrepresents the minimum concentration at which method performance becomes quantitative and is not subject to t
31、he degree ofvariation observed at concentrations between the MDL and the RDL.3.2.10spiked blank (SB)an aliquot of reagent water to which known concentrations of analyte(s) is added in the laboratory,using the same solution as used to prepare the matrix spike. The spike blank is analyzed using the sa
32、me sample preparation,analytical method and QA/QC procedure used for test samples. The purpose of the spike blank is to determine whether methodperformance is within acceptable limits. The spike blank is also useful for troubleshooting matrix spike results that are outside theacceptance limits, by a
33、llowing the analyst to differentiate between spike solution and spiking technique problems and matrixinterferences. Recommended spike levels are listed in Annex, spiked blank (SB), na reagent-water aliquot to which knownconcentrations of analyte(s) are added in the laboratory, using the same solutio
34、n as used to prepare the matrix spike.3.2.9.1 DiscussionThe spike blank is analyzed using the same sample preparation, analytical method and QA/QC procedureused for test samples. The purpose of the spike blank is to determine whether method performance is within acceptable limits. Thespike blank is
35、also useful for troubleshooting matrix-spike results that are outside the acceptance limits, by allowing the analystto differentiate between: 1) spike-solution and spiking-technique problems and 2.) matrix interferences. Recommended spike levelsare listed in Annex, Table A1.3.3.2.10 stock-standard s
36、olution, na concentrated solution (containing one or more analytes), obtained as a certified solutionfrom a reputable source.3.2.11 stock standard solutiona concentrated solution containing one or more analytes, obtained as a certified solution forma reputable source. surrogate spikes, nlanthanum an
37、d terbium are added at a concentration of 5 ng/mL (each) in the initial100-mL sample.D6800 1223.2.11.1 DiscussionThe surrogate spikes are then preconcentrated to approximately 50 ng/mL in the final 10-mL samplewithout correcting for the final preconcentration. The surrogate spikes are used to determ
38、ine potential method problems such asimproper pH adjustment or faulty filters used when collecting the precipitate.3.2.12 surrogate spikeslanthanum and terbium are added at a concentration of 5 ng/mL in the initial 100-mL sample. Thesurrogate spikes are then preconcentrated to approximately 50 ng/mL
39、 in the final 10-mL sample not correcting for the finalpreconcentration. The surrogate spikes are used to determine potential method problems such as improper pH adjustment or faultyfilters used when collecting the precipitate.3.2.13total recoverabletotal recoverable, nthe concentration of analyte d
40、etermined on a whole, unfiltered water or solid samplefollowing vigorous digestion as described in US EPA Method 1640.4. Summary of Practice4.1 In this practice, trace elements are separated from seawater matrix elements (in particular Na, Ca, and Mg) andpreconcentrated by a factor of 10 by reductiv
41、e precipitation using sodium borohydride as a reducing agent.4.2 Iron (Fe) and palladium (Pd) are added to the samples to aid co-precipitation of metal borides and to enhance theprecipitation of metals in their elemental form.4.3 For total metals, the whole sample is acidified at the time of collect
42、ion with ultrapure nitric acid at an equivalentconcentration of 0.20 % to a pH 75% to ensure sample preparation integrity.12.1.2.3Spike Blank (SB)Spike blanks should be two to ten times the MDLor estimated sample concentrations. One SB shouldbe prepared and analyzed for each analytical batch and aft
43、er five SB samples control limits for each analyte should be determinedfrom the mean percent recovery and the standard deviation of the percent recovery. All upper and lower control limits should becalculated using the following equations:Uppercontrollimit5X13SD6800-02R07E01_1Lowercontrollimit5X23SD
44、6800-02R07E01_112.4.1 To ensure that the test method is in control, analyze a LCS containing a mid-range concentration of the analyte with eachbatch every 10 samples if large numbers of samples are analyzed in the batch. The LCS must be taken through all of the steps ofthe analytical method includin
45、g sample preservation and pretreatment. The result obtained for the LCS shall fall within 6 15 %of the known concentration.12.4.2 If the result is not within these limits, analysis of samples is halted until the problem is corrected, and either all thesamples in the batch must be reanalyzed, or the
46、results must be qualified with an indication that they do not fall within theperformance criteria of the test method.12.5 Method Blank:12.5.1 Analyze a reagent water test blank with each batch. The concentration of the analyte found in the blank should be lessthan 0.5 times the lowest calibration st
47、andard. If the concentration of the analyte is found above this level, analysis of samples ishalted until the contamination is eliminated and a blank shows no contamination at or above this level, or the results must bequalified with an indication that they do not fall within the performance criteri
48、a of the test method.12.6 Matrix Spike (MS):12.6.1 To check for interferences in the specific matrix being tested, perform a MS on at least one sample from each batch byspiking an aliquot of the sample with a known concentration of the analyte and taking it through the analytical method.12.6.2 The s
49、pike concentration plus the sample concentration of the analyte must not exceed the high calibration standard. Thespike must produce a concentration in the spiked sample that is 2 to 5 times the analyte concentration in the unspiked sample, or10 to 50 times the detection limit of the test method, whichever is greater.12.6.3 Calculate the percent recovery of the spike (P) using the following formula: P 5 100AVs1 V! BVs#/CVAwhere:whereSA = Standard Deviation of the percent recovery, and analyte known concentration (g/L) in spiked sample,XB = M
