1、Designation:D623909(Reapproved 2015)Standard Test Method forUranium in Drinking Water by High-Resolution Alpha-Liquid-Scintillation Spectrometry1This standard is issued under the fixed designation D6239;the number immediately following the designation indicates the year oforiginal adoption or,in the
2、 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.Scope1.1 This test method covers determining the total solubleuranium activity in drinking water in th
3、e range of 0.037 Bq/L(1 pCi/L)or greater by selective solvent extraction andhigh-resolution alpha-liquid-scintillation spectrometry.The en-ergy resolution obtainable with this technique also allowsestimation of the238U to234U activity ratio.1.2 This test method was tested successfully with reagentwa
4、ter and drinking water.It is the users responsibility toensure the validity of this test method for waters of untestedmatrices.1.3 The values stated in SI units are to be regarded asstandard.The values given in parentheses are for informationonly.1.4 This standard does not purport to address all of
5、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.For specific hazardstatements,see Section 9.2.Referenced Documents2.1 A
6、STM Standards:2D1129 Terminology Relating to WaterD1193 Specification for Reagent WaterD2777 Practice for Determination of Precision and Bias ofApplicable Test Methods of Committee D19 on WaterD3370 Practices for Sampling Water from Closed ConduitsD3648 Practices for the Measurement of Radioactivity
7、D5847 Practice for Writing Quality Control Specificationsfor Standard Test Methods for Water AnalysisD7282 Practice for Set-up,Calibration,and Quality Controlof Instruments Used for Radioactivity Measurements3.Terminology3.1 Definitions:3.1.1 For definitions of terms used in this test method,referto
8、 Terminology D1129.For terms not included in thisreference,refer to other published glossaries(1).34.Summary of Test Method4.1 This test method is based on solvent extraction technol-ogy to isolate and concentrate uranium in drinking water forcounting via a high-resolution alpha-liquid-scintillation
9、 spec-trometer.4.2 To determine total uranium,as well as limited isotopicuranium(238U and234U)by activity in drinking water,a200mL acidified water sample is first spiked with232U as anisotopic tracer,boiled briefly to remove radon,and evaporateduntil less than 50 mL remain.The solution is then madea
10、pproximately 0.01 M in diethylenetriaminepentaacetic acid(DTPA)and the pH is adjusted to between 2.5 and 3.0.Thesample is transferred to a separatory funnel and equilibratedwith 1.50 mL of an extractive scintillator containing a dialkylphosphoric acid extracting agent.Under these conditions onlyuran
11、ium is quantitatively transferred to the organic phase whilethe extraction of undesired ions is masked by the presence ofDTPA.Following phase separation,1.00 mL of the organicphase is sparged with dry argon gas to remove oxygen,achemical quench agent,and counted on a high-resolutionalpha-liquid-scin
12、tillation spectrometer and multichannel ana-lyzer(MCA).4.3 The alpha spectrum of a sample that contains naturaluranium and that is analyzed with an internal232U tracer willappear similar to the spectrum in Fig.1.An approximateresolution of 250 keV FWHM for238U(4.2 MeV)allowsresolution and analysis o
13、f the238U,234U,and232U energyspectrum peaks when their activities are of the same order ofmagnitude.Resolution of the235U(4.4 MeV)alpha peak is notpossible,but its activity,which accounts for approximately1This test method is under the jurisdiction of ASTM Committee D19 on Waterand is the direct res
14、ponsibility of Subcommittee D19.04 on Methods of Radiochemi-cal Analysis.Current edition approved Jan.1,2015.Published January 2015.Originallyapproved in 1998.Last previous edition approved in 2009 as D6239 09.DOI:10.1520/D6239-09R15.2For referenced ASTM standards,visit the ASTM website,www.astm.org
15、,orcontact ASTM Customer Service at serviceastm.org.For Annual Book of ASTMStandards volume information,refer to the standards Document Summary page onthe ASTM website.3The boldface numbers in parenthesis refer to the list of references at the end ofthe text.Copyright ASTM International,100 Barr Har
16、bor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 2.2%of the total natural uranium activity,is included in thetotal uranium activity calculated when the238U and234U peaksare in the region of interest(ROI).When the238U and234Upeaks are integrated separately,a portion of the235U activitywill be included in the238U activity and the rest in the234Uactivity,depending on the exact ROIs selected.Likewise,ifpresent,236U and233U will not be resolved by the spectrom-eter;however,their a
