1、Designation: D7939 15Standard Test Method forRapid Radiochemical Determination of Americium-241 inWater1This standard is issued under the fixed designation D7939; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last rev
2、ision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method is specifically for Americium-241(241Am) in drinking water and other aqueous samples.However, if any isotopes
3、 of curium are present in the sample,they will be carried with americium during the analyticalseparation process and will be observed in the final alphaspectrum. The presence of243Am in the water sample will biasthe results obtained by this test method.1.2 This test method is applicable to samples i
4、n whichradioactive contamination is from either known or unknownorigins. If any filtration of the sample is performed beforestarting the analysis, those solids should be analyzed sepa-rately. The results from the analysis of these solids should bereported separately (as a suspended activity concentr
5、ation forthe water volume filtered) but identified with the filtrate results.1.3 This test method is applicable to the determination ofsoluble241Am. This test method is not applicable to thedetermination of241Am in highly insoluble particulate matterpossibly present in water samples contaminated as
6、a result of aradiological dispersal device (RDD) event.1.4 This test method uses rapid radiochemical separationtechniques for determining americium in water samples fol-lowing a radiological or nuclear incident. Although, with thistest method, concentrations of241Am on the same order ofmagnitude as
7、methods used for the Safe Drinking Water Act(SDWA) can be detected, this test method is not a substitute forSDWA-approved methods for241Am.1.5 UnitsThe values stated in SI units are to be regardedas the standard. No other units of measurement are included inthis standard.1.6 This standard does not p
8、urport to address all of thesafety concerns, if any, associated with its use. It is 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.2. Referenced Documents2.1 ASTM Standards:2
9、C1163 Practice for MountingActinides forAlpha Spectrom-etry Using Neodymium FluorideC1284 Practice for Electrodeposition of the Actinides forAlpha SpectrometryD1129 Terminology Relating to WaterD1193 Specification for Reagent WaterD3370 Practices for Sampling Water from Closed ConduitsD4448 Guide fo
10、r Sampling Ground-Water Monitoring WellsD5847 Practice for Writing Quality Control Specificationsfor Standard Test Methods for Water AnalysisD6001 Guide for Direct-Push Groundwater Sampling forEnvironmental Site CharacterizationD7282 Practice for Set-up, Calibration, and Quality Controlof Instrument
11、s Used for Radioactivity Measurements3. Terminology3.1 DefinitionsFor definitions of terms used in this testmethod, refer to Terminology D1129.3.2 Definitions of Terms Specific to This Standard:3.2.1 analytical action level, AAL, ndenotes the value of aquantity that will cause the decision maker to
12、choose analternative action.3.2.2 analytical protocol specifications, APS, noutput of adirected planning process that contains the projects analyticaldata needs and requirements in an organized, concise form.3.2.3 discrete radioactive particles, DRPs or hot particles,nparticulate matter in a sample
13、of any matrix in which a highconcentration of radioactive material is contained in a tinyparticle (micrometre range).3.2.4 measurement quality objective, MQO, nanalyticaldata requirements of the data quality objectives; project- orprogram-specific.3.2.4.1 DiscussionThey can be quantitative or qualit
14、ative.MQOs serve as measurement performance criteria or objec-tives of the analytical process.1This test method is under the jurisdiction of ASTM Committee D19 on Waterand is the direct responsibility of Subcommittee D19.04 on Methods of Radiochemi-cal Analysis.Current edition approved Jan. 1, 2015.
15、 Published January 2015. DOI: 10.1520/D7939-15.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.Copyright ASTM
16、 International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States13.2.5 radiological dispersal device, RDD,nunconventional weapon constructed to distribute radioac-tive material(s) into the environment either by incorporatingthem into a conventional bomb or using sp
17、rays, canisters, ormanual dispersal, that is, a “dirty bomb.”3.2.6 required method uncertainty, uMR,ntarget value forthe individual measurement uncertainties and an estimate ofuncertainty (of measurement) before the sample is actuallymeasured.3.2.6.1 DiscussionThe required method uncertainty is ap-p
18、licable below an AAL.3.2.7 required relative method uncertainty, MR,nthevalue, uMR, divided by the AAL and typically expressed as apercentage.3.2.7.1 DiscussionIt is applicable above the AAL.3.2.8 sample test source, STS, nfinal form of the samplethat is used for nuclear counting.3.2.8.1 DiscussionT
19、his form is usually specific for thenuclear counting technique used in this test method, such as asolid deposited on a filter for alpha spectrometry analysis.3.3 Acronyms:3.3.1 AALanalytical action level3.3.2 APSanalytical protocol specification3.3.3 DRPsdiscrete radioactive particles3.3.4 IRMindepe
20、ndent reference material3.3.5 MARLAPMulti-Agency Radiological LaboratoryAnalytical Protocols Manual33.3.6 MDCminimum detectable concentration3.3.7 MQOmeasurement quality objective3.3.8 NISTNational Institute of Standards andTechnologyUnited States3.3.9 NPLNational Physical LaboratoryUnited King-dom3
21、.3.10 RDDradiological dispersal device3.3.11 STSsample test source4. Summary of Test Method4.1 This test method is based on a sequence of twochromatographic extraction resins used to concentrate, isolate,and purify americium by removing interfering radionuclides aswell as other components of the wat
22、er matrix to prepare theamericium fraction for counting by alpha spectrometry. Thistest method uses vacuum-assisted flow to improve the speed ofthe separations. Before the use of the extraction resins, thewater sample is filtered as necessary to remove any insolublefractions, equilibrated with ameri
23、cium-243 (243Am) tracer, andconcentrated by evaporation or calcium phosphate precipita-tion. The sample test source (STS) is prepared by micropre-cipitation with neodymium(III) fluoride (NdF3). Standard labo-ratory protocol for the use of an alpha spectrometer should beused when the sample is ready
24、for counting.5. Significance and Use5.1 This test method is considered a rapid method whencompared to other classical methods for the determination of241Am in aqueous solutions. During the method validation ofthis method, a test batch of fourteen test samples plus qualitycontrol samples was chemical
25、ly processed in 7.5 hours.Additional time for counting the samples depends on themeasurement quality objectives.5.2 This test method is specific forAmericium-241 (241Am)in drinking water and other aqueous samples. However, if anyisotopes of curium are present in the sample, they will becarried with
26、americium during the analytical separation processand will be observed in the final alpha spectrum.5.3 This test method is capable of achieving a requiredmethod uncertainty for241Am of 0.070 Bq/L at an analyticalaction level of 0.555 Bq/L. This test method is capable ofachieving a required relative
27、method uncertainty, MR,13%above 0.555 Bq/L. This test method is capable of achieving a“required” minimum detectable concentration (MDC) of 0.055Bq/L.5.4 To attain these stated measurement quality objectives(MQOs), a sample volume of approximately 200 mLand counttime of at least 1 to 3 hours are reco
28、mmended. The sampleturnaround time and throughput may vary based on additionalproject MQOs, the time for analysis of the final counting form,and initial sample volume. This test method should be vali-dated before use following the protocols provided in MethodValidation Guide for Qualifying Methods U
29、sed by Radiologi-cal Laboratories Participating in Incident ResponseActivities.45.5 This test method is intended to be used for watersamples that are similar in composition to drinking water. Thismethod was evaluated following the guidance presented for“Level E Method Validation: Adapted or Newly De
30、velopedMethods, Including Rapid Methods” in Method ValidationGuide for Qualifying Methods Used by Radiological Labora-tories Participating in Incident ResponseActivities and Chapter6 of MARLAP, 2004.3Multi-radionuclide analysis using se-quential separation may be possible using this test method inco
31、njunction with other rapid methods.6. Interferences6.1 RadiologicalAlpha-emitting radionuclides with irre-solvable alpha energies, such as241Am (5.48 MeV),238Pu(5.50 MeV), and228Th (5.42 MeV), shall be chemicallyseparated to enable radionuclide-specific measurements. Thistest method separates these
32、radionuclides effectively. Thesignificance of peak overlap will be determined by the indi-vidual detectors alpha energy resolution characteristics andthe quality of the final precipitate that is counted.6.2 Tracer ImpurityThe presence of241Am may be foundin243Am tracer solutions. Newly acquired243Am
33、 tracersolutions shall be analyzed before use to verify the absence of241Am activity.3Multi-Agency Radiological Laboratory Analytical Protocols Manual(MARLAP), EPA 402-B-1304 04-001A, Vol I, Chaps. 6, 7, and 20, Glossary; VolsII and III, Appendix G, July 2004, www.epa.gov/radiation/ marlap/index.htm
34、l4Method Validation Guide for Radiological Laboratories Participating inIncident Response Activities, Revision 0, U.S. Environmental Protection Agency,Office of Air and Radiation, Washington, DC, EPA 402-R-09-006, June 2009,www.epa.gov/narel/incident_guides.html and www.epa.gov/erln/radiation.html.D
35、7939 1526.3 Non-RadiologicalVery high levels of competinghigher valence anions (greater than divalent such as phos-phates) will lead to lower yields when using the evaporationoption because of competition with active sites on the resin. Ifhigher valence anions are present, the phosphate precipitatio
36、noption may need to be used initially in place of evaporation. Ifcalcium phosphate coprecipitation is performed to collectamericium (and other potentially present actinides) from large-volume samples, the amount of phosphate added to coprecipi-tate the actinides (in 12.1.4.1) should be reduced to ac
37、commo-date the samples high phosphate concentration.7. Apparatus7.1 Analytical balance, with a 10-4-g readability or better.7.2 Centrifuge, able to accommodate 225- to 250-mLflasks.7.3 Centrifuge tubes, plastic, 15-, 25-, and 50-mL capacity,or equivalent.7.4 Centrifuge flasks, 225- to 250-mL capacit
38、y.7.5 Filter, 0.45-m membrane.7.6 pH Paper, 1.0 to 4.0.7.7 Filter apparatus, 25-mm-diameter, polysulfone filtra-tion chimney, stem support, and stainless steel support, orequivalent. A single-use (disposable) filter funnel/filter combi-nation may be used to avoid cross-contamination.7.8 Filter, 25-m
39、m membrane, 0.1-m pore size orequivalent, polypropylene, polycarbonate, or equivalent.7.9 Stainless steel planchets, or other sample mounts able tohold the 25-mm filter.7.10 Tweezers.7.11 Pipette, 100-L or equivalent and appropriate plastictips.7.12 Reservoirs, with male Luer connector, 10 or 20-mLs
40、yringe style.7.13 Vacuum box system, compatible with standard Luer-tipped SPE columns and appropriate connectors.7.13.1 Vacuum box and lid, capable of being thoroughlycleaned, including eluate ports.7.13.2 Disposable eluate connectors/liners, specific to thebox lid.7.13.3 Inner rack, with 30-mm diam
41、eter holes (for 50-mLcentrifuge tubes).7.14 Vortex mixer.7.15 Vacuum source.7.16 Miscellaneous laboratory ware, plastic or glass, 25, 50,100, 250, and 350 mL.8. Reagents and Standards8.1 Purity of ReagentsReagent grade chemicals shall beused in all tests. Unless otherwise indicated, it is intended t
42、hatall reagents shall conform to the specifications of the commit-tee on Analytical Reagents of the American Chemical Society,where such specifications are available.5Other grades may beused, provided that that the reagent is of sufficient high purityto permit its use without increasing the backgrou
43、nd of themeasurement. Some reagents, even those of high purity, maycontain naturally occurring radioactivity, such as isotopes ofuranium, radium, actinium, thorium, rare earths and potassiumcompounds, or artificially produced radionuclides, or anycombination thereof. Consequently, when such reagents
44、 areused in the analysis of low-radioactivity samples, the activityof the reagents shall be determined under analytical conditionsthat are identical to those used for the sample. The activitycontributed by the reagents should be considered to be acomponent of background and applied as a correction w
45、hencalculating the test sample result. The increased backgroundmay reduce the sensitivity of the measurement.8.2 Purity of WaterUnless otherwise indicated, referencesto water shall be understood to mean reagent water as definedby Type 1 of Specification D1193. All solutions used inmicroprecipitation
46、 should be prepared with water filteredthrough a 0.45-m (or better) filter.8.3 Am-243 Tracer SolutionAdd 0.22 to 0.37 Bq243Amper aliquant; activity added known to at least 5 % (combinedstandard uncertainty 5 %).8.4 Ammonium Hydrogen Phosphate (NH4)2HPO4(3.2M)Dissolve 106 g of (NH4)2HPO4in 200 mL of
47、water,heat gently to dissolve, and dilute to 250 mL with water.8.5 Ammonium Hydroxide (NH4OH)(15M)Concentrated,available commercially.8.6 Ammonium Thiocyanate (NH4SCN) Indicator (1M)Dissolve 7.6 g of NH4SCN in 90 mLof water and dilute to 100mL with water. An appropriate quantity of sodium thiocyanat
48、e(8.1 g) or potassium thiocyanate (9.7 g) may be substituted forNH4SCN.8.7 Ascorbic Acid (C6H8O6) (1M)Dissolve 17.6 g ofC6H8O6in 90 mL of water and dilute to 100 mL with water.Prepare weekly.8.8 Calcium Nitrate (0.9M)Dissolve 53 g of calciumnitrate tetrahydrate (Ca(NO3)24H2O) in 100 mL of water andd
49、ilute to 250 mL with water.8.9 Ethanol, 100 %Anhydrous C2H5OH, available com-mercially.8.9.1 Ethanol (80 % v/v)Mix 80-mL 100 % ethanol and20-mL water.8.10 Ferrous Sulfamate (0.6M)Add 57 g of sulfamic acid(NH2SO3H) to 150 mL of water and heat to 70C. Slowly add7 g of iron powder (100-mesh size) while heating and stirringwith a magnetic stirrer until dissolved (may take as long as 2h). Filter the hot solution using a qualitative filter, transfer toflask, and dilute to 200 mL with water. Prepare fresh weekly.5Reagent Chemicals, Am
