ASTM D1971-2002(2006) Standard Practices for Digestion of Water Samples for Determination of Metals by Flame Atomic Absorption Graphite Furnace Atomic Absorption Plasma Emission Sp.pdf

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1、Designation: D 1971 02 (Reapproved 2006)Standard Practices forDigestion of Water Samples for Determination of Metals byFlame Atomic Absorption, Graphite Furnace AtomicAbsorption, Plasma Emission Spectroscopy, or PlasmaMass Spectrometry1This standard is issued under the fixed designation D 1971; the

2、number immediately following the designation 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 (e) indicates an editorial change since the last revision or reapproval.1. S

3、cope1.1 Most atomic absorption and plasma emission spectros-copy, and plasma-mass spectrometric test methods require thatthe metals of interest be dissolved in a liquid phase beforebeing introduced into the spectrophotometer. These practicesdescribe digestion or dissolution procedures whereby analyt

4、emetals associated with the solid fraction of a sample can bebrought into solution for subsequent analysis. The followingpractices are included:SectionsPractice ADigestion with Mineral Acids andElevated Pressure8 through 13Practice BDigestion with Mineral Acids andHeating at Atmospheric Pressure14 t

5、hrough 19Practice CIn-bottle digestion with Mineral Acids 20 through 251.2 These practices have been demonstrated to be applicableto a wide variety of sample types and sample matrices, and inmany cases, will give complete dissolution of the analytemetals of interest. They are by no means the only di

6、gestionprocedures available.1.3 The user of these practices should be cautioned thatthese practices may not completely dissolve all portions of asamples solid phase and may not give complete recovery ofthe desired analyte metals. In these cases, other digestiontechniques are available that will effe

7、ct complete dissolution ofa sample. It is the users responsibility to ensure the validity ofthese practices for use on their particular sample matrix, fortheir metals of interest.1.4 This practice assumes that the criteria established inGuide D 3856 can be met.1.5 These digestion procedures have bee

8、n selected for theirwide application, low cost, and ease of use.1.6 The values stated in SI units are to be regarded as thestandard. The values given in parentheses are for informationonly.1.7 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is

9、 theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use. Specific hazardstatements are given in Section 6.2. Referenced Documents2.1 ASTM Standards:2D511 Test Methods for Calcium and

10、 Magnesium In WaterD 857 Test Method for Aluminum in WaterD 858 Test Methods for Manganese in WaterD 1068 Test Methods for Iron in WaterD 1129 Terminology Relating to WaterD 1192 Guide for Equipment for Sampling Water andSteam in Closed Conduits3D 1193 Specification for Reagent WaterD 1687 Test Meth

11、ods for Chromium in WaterD 1688 Test Methods for Copper in WaterD 1691 Test Methods for Zinc in WaterD 1886 Test Methods for Nickel in WaterD 1976 Test Method for Elements in Water by Inductively-Coupled Argon Plasma Atomic Emission SpectroscopyD 3370 Practices for Sampling Water from Closed Conduit

12、sD 3372 Test Method for Molybdenum in WaterD 3557 Test Methods for Cadmium in WaterD 3558 Test Methods for Cobalt in WaterD 3559 Test Methods for Lead in WaterD 3645 Test Methods for Beryllium in WaterD 3856 Guide for Good Laboratory Practices in Laborato-ries Engaged in Sampling and Analysis of Wat

13、erD 3866 Test Methods for Silver in WaterD 3919 Practice for Measuring Trace Elements in Water byGraphite Furnace Atomic Absorption Spectrophotometry1These practices are under the jurisdiction of ASTM Committee D19 on Waterand are the direct responsibility of Subcommittee D19.05 on Inorganic Constit

14、uentsin Water.Current edition approved Dec. 15, 2006. Published February 2007. Originallyapproved in 1991. Last previous edition approved in 1995 as D 1971 95.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of

15、ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Withdrawn.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.D 4190 Test Method for Elements in Water by Direct-Current Plasma Atomic Emi

16、ssion SpectroscopyD 4191 Test Method for Sodium in Water by AtomicAbsorption SpectrophotometryD 4192 Test Method for Potassium in Water by AtomicAbsorption SpectrophotometryD 4309 Practice for Sample Digestion Using Closed VesselMicrowave Heating Technique for the Determination ofTotal Metals in Wat

17、erD 4691 Practice for Measuring Elements in Water by FlameAtomic Absorption SpectrophotometryD 5673 Test Method for Elements in Water by InductivelyCoupled PlasmaMass Spectrometry2.2 U.S. EPA Method:EPA-600/4-79-020 Methods for Chemical Analysis of Wa-ter and Wastes4EPA-600/R-94/111 Methods for the

18、Determination of Met-als in Environmental SamplesSupplement 142.3 U.S. Geological Survey Method:U.S. Geological Survey Open File Report 96225: Methodsof Analysis by the U.S. Geological Survey National WaterQuality LaboratoryIn-Bottle Acid Digestion of WholeWater Samples5Quality LaboratoryIn-Bottle A

19、cid Digestion of WholeWater Samples53. Terminology3.1 Definitions: For definitions of terms used in thesepractices, refer to Terminology D 1129.3.2 Definitions of Terms Specific to This Standard:3.2.1 digestiontreating a sample with the use of heat orelevated pressures, or both, usually in the prese

20、nce of chemicaladditives, to bring analytes of interest into solution or toremove interfering matrix components, or both.3.2.2 total recoverablethe amount of a metal analytemeasurable by atomic absorption spectrophotometry, plasmaemission spectroscopy or plasma mass spectrometry afterapplying the di

21、gestion procedure in either Practice A, PracticeB, or Practice C. The choice of Practice A, B, or C shall benoted in reporting resultant data.4. Significance and Use4.1 The determination of metals in water often requires themeasurement of total (suspended and dissolved) metals as wellas soluble (dis

22、solved) metals. In such cases, consistent anddependable digestion procedures must be used so that dataderived for the total metals content is reliable.4.2 The practices given are applicable to a wide variety ofsample types for the purpose of preparing a sample for metalsanalyses by atomic absorption

23、 spectrophotometry or plasmaemission spectroscopy (see Test Methods D 1976, D 3919,D 4691, and D 4190) or plasma-mass spectrometry (See TestMethod D 5673) and have been shown to give good recoveryin the following matrices: industrial effluents; waste watertreatment plant influents, sludges, dewatere

24、d sludges, andeffluents; river and lake waters; and plant and animal tissues.Elements which have shown good recovery include: copper,nickel, lead, zinc, cadmium, iron, manganese, magnesium, andcalcium.4.2.1 Good recovery for the indicated sample types andmetals may not be achieved at all times due t

25、o each samplesunique characteristics. Users must always validate the practicefor their particular samples.4.3 The analytical results achieved after applying thesepractices cannot necessarily be deemed as a measure ofbioavailable or environmentally available elements.4.4 These three practices may not

26、 give the same recoverywhen applied to the same sample, nor will they necessarilygive the same results as achieved using other digestiontechniques. An alternate digestion technique is PracticeD 4309.5. Reagents5.1 Purity of ReagentsReagent grade chemicals shall beused throughout. Acids shall have a

27、low-metal content orshould be doubly distilled and checked for purity. Unlessotherwise indicated, it is intended that all reagents shallconform to the Specifications of the Committee on AnalyticalReagents of the American Chemical Society.6Other gradesmay be used, provided it is first ascertained tha

28、t the reagent isof sufficiently high purity to permit its use without lesseningthe accuracy of the determination.5.2 Purity of WaterUnless otherwise indicated, referencesto water shall be understood to mean reagent water conformingto Specification D 1193, Type I. Other reagent water types maybe used

29、, provided it is first ascertained that the water is ofsufficiently high purity to permit its use without lessening thebias and precision of the determination.6. Hazards6.1 These practices involve the heating of solutions ofmineral acids.Appropriate precautions shall be taken to protectthe analyst f

30、rom these acids and heated containers. Heatedsamples and acids may splatter or boil unexpectedly.7. Sampling7.1 As with all chemical assay procedures, the user of thispractice shall ensure that all sample aliquot used are adequatelyrepresentative of the environmental situation being monitored.7.2 Ap

31、propriate sampling and subsampling techniques forparticular environmental samples can be found in other refer-ences.7.3 Collect the sample in accordance with SpecificationD 1192 and Practices D 3370.4Revised March 1983. Published by the United States Environmental ProtectionAgency. Available from Su

32、perintendent of Documents, U.S. Government PrintingOffice, Washington, DC 20402.5Available from USGS National Center, 12201 Sunrise Valley Dr., Reston, VA20192, USA.6Reagent Chemicals, American Chemical Society Specifications , AmericanChemical Society, Washington, DC. For suggestions on the testing

33、 of reagents notlisted by the American Chemical Society, see Analar Standards for LaboratoryChemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeiaand National Formulary, U.S. Pharmaceutical Convention, Inc. (USPC), Rockville,MD.D 1971 02 (2006)2PRACTICE ADIGESTION WITH MINERALA

34、CIDS ANDELEVATED PRESSURE8. Scope8.1 This practice presents a digestion technique that hasbroad application and can be performed inexpensively withminimal labor, equipment, and space. In addition, this practiceallows for many samples to be processed quickly and simul-taneously under the same conditi

35、ons.9. Summary of Practice9.1 Samples are placed in loosely capped, heat-, and aci-dresistant containers with selected reagents and subjected to121C and 15 psig (103 kPa gage) for 30 min. After removingany particulate matter remaining, the digestate is ready foranalysis by atomic absorption spectrop

36、hotometry, plasmaemission spectroscopy, or plasma-mass spectrometry.9.2 The practice may be found to be more applicable to aparticular sample or analytical scheme after appropriate modi-fications of reagent addition, temperature, pressure, digestiontime, or container selection. Any such modification

37、s to thispractice must be validated by the user.10. Apparatus10.1 Digestion Containers50 mL disposable polypropy-lene centrifuge tubes and 125 mL polypropylene reagentbottles with screw caps have been used successfully. Anycontainer that is not attacked by the digestion conditions, issufficiently fr

38、ee of the analyte(s) of interest, and can be looselycapped, may be used.10.2 Digestion Container RackAny rack that will fitinside the autoclave, will hold the digestion containers se-curely, and is not attacked by the conditions in the autoclave,may be used.10.3 AutoclaveAny autoclave or similar app

39、aratus with apressure chamber large enough to hold the desired number ofsamples and capable of achieving and holding 121C and 15psig (103 kPa gage) for 30 min., may be employed. Anautoclave with automatic cycling is desirable. As the digestingsamples release acidic fumes, the portions of the autocla

40、vecoming in contact with these fumes should be constructed ofacid resistant materials.NOTE 1Prolonged use of an autoclave with a stainless steel interiorfor this practice may result in discoloration of the autoclave walls. Thisdiscoloration has not been shown to cause any problems with autoclaveoper

41、ation. A commercially available autoclave with a stainless steelinterior has been in daily use for this practice, as well as for routinesterilization purposes, for ten years without any degradation of theautoclave or its performance.11. Interferences11.1 The interferences of this practice relate to

42、the inabilityof the described procedure to quantitatively dissolve theanalyte metals of interest in certain situations. These interfer-ences can be either physical or chemical.11.2 Physical InterferencesIn some samples, the metalsof interest are bound or occluded in a matrix that is imperviousto dis

43、solution by the acids. This is most frequently encounteredin geological and boiler water samples.11.3 Chemical InterferencesThe complete dissolution ofa metal of interest may not occur due to the digestionconditions being insufficiently rigorous for that particularmetal. In other instances, the chem

44、ical makeup of the samplemay render the digestion acids ineffective.12. Reagents12.1 Hydrochloric Acid (sp gr 1.19)Concentrated hydro-chloric acid (HCl).12.2 Nitric Acid (sp gr 1.42)Concentrated nitric acid(HNO3).13. Procedures13.1 In this section two types of digestion procedures aredescribed: one

45、for liquid samples (see 13.2) and one for solidand semi-solid samples (see 13.3).13.2 Liquid Samples:13.2.1 Using a sample volume from 40 to 100 mL, pipet analiquot of sample, hydrochloric acid, and nitric acid into adigestion container in the following ratio: 100 volumes sampleto 5 volumes HCl (sp

46、gr 1.19) to 1 volume HNO3(sp gr 1.42).13.2.2 Swirl digestion container gently to mix contents.13.2.3 Loosely place caps on digestion containers and placedigestion containers in rack.NOTE 2Caps should be attached securely enough so that they are notthrown off during autoclaving, but not so securely t

47、hat gas is unable tomove freely in and out of the container.13.2.4 Place rack of digestion containers in autoclave andprocess for 30 min. at 121C and 15 psig (103 kPa gage).13.2.5 Remove digestion containers from autoclave; allowto cool to room temperature.13.2.6 Proceed with assay of digested sampl

48、e.NOTE 3Experience with this practice indicated that with sample andacid volumes in the ranges specified in 13.2.1 final volume afterautoclaving will approximate the original sample volume within 1 %. If,after verifying this observation and determining if this degree of volu-metric uncertainty is ac

49、ceptable, the user may proceed to use the digestatewithout any volume correction. In cases where the final volume afterautoclaving is not sufficiently close to the original sample volume,experience indicates that the final volume will still be very reproducible.In these cases and where the final digestate volume is less than the originalvolume of sample, a fixed volume of water can be added to the digestateto make its volume closely approximate the original sample volume.Conversely, a sufficient volume of water can be added prior to autoclav-ing, such tha