ASTM_D_2460_-_07_2013.pdf

Designation:D246007(Reapproved 2013)Standard Test Method forAlpha-Particle-Emitting Isotopes of Radium in Water1This standard is issued under the fixed designation D2460;the 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()indicates an editorial change since the last revision or reapproval.1.Scope1.1 This test method covers the separation of dissolvedradium from water for the purpose of measuring its radioac-tivity.Although all radium isotopes are separated,the testmethod is limited to alpha-particle-emitting isotopes by choiceof radiation detector.The most important of these radioisotopesare223Ra,224Ra,and226Ra.The lower limit of concentration towhich this test method is applicable is 3.7 10-2Bq/L(1 pCi/L).1.2 This test method may be used for absolute measure-ments by calibrating with a suitable alpha-emitting radioiso-tope such as226Ra,or for relative methods by comparingmeasurements with each other.Mixtures of radium isotopesmay be reported as equivalent226Ra.Information is alsoprovided from which the relative contributions of radiumisotopes may be calculated.1.3 This standard does not purport 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.For a specificprecautionary statement,see Section 9.2.Referenced Documents2.1 ASTM Standards:2C859 Terminology Relating to Nuclear MaterialsD1129 Terminology Relating to WaterD1193 Specification for Reagent WaterD1943 Test Method for Alpha Particle Radioactivity ofWaterD2777 Practice for Determination of Precision and Bias ofApplicable Test Methods of Committee D19 on WaterD3370 Practices for Sampling Water from Closed ConduitsD3454 Test Method for Radium-226 in WaterD3648 Practices for the Measurement of RadioactivityD4448 Guide for 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 Characterization3.Terminology3.1 Definition:3.1.1 For definitions of terms used in this standard,seeTerminologies C859 and D1129.For terms not included inthese,reference may be made to other published glossaries(1,2).34.Summary of Test Method4.1 Radium is collected from the water by coprecipitationwith mixed barium and lead sulfates.The barium and leadcarriers are added to a solution containing alkaline citrate ionwhich prevents precipitation until interchange has taken place.Sulfuric acid is then used to precipitate the sulfates,which arepurified by nitric acid washes.The precipitate is dissolved inammoniacal EDTA.The barium and radium sulfates arereprecipitated by the addition of acetic acid,thereby separatingthem from lead and other radionuclides.The precipitate isdried on a planchet,weighed to determine the chemical yield,and alpha-counted to determine the total disintegration rate ofalpha-particle-emitting radium isotopes.This procedure isbased upon published ones(3,4).5.Significance and Use5.1 Radium is one of the most radiotoxic elements.Itsisotope of mass 226 is the most hazardous because of its longhalf-life.The isotopes 223 and 224,although not as hazardous,are of some concern in appraising the quality of water.5.2 The alpha-particle-emitting isotopes of radium otherthan that of mass 226 may be determined by difference ifradium-226 is measured separately,such as by Test MethodD3454.Note that one finds226Ra and223Ra together in variableproportions(5,6),but224Ra does not normally occur with1This 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.1,2013.Published January 2013.Originallyapproved in 1966.Replaces D246066 T.Last previous edition approved in 2007 asD2460 07.DOI:10.1520/D2460-07R13.2For 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.3The boldface numbers in parentheses refer to the list of references at the end ofthis standard.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 them.Thus,223Ra often may be determined by simply sub-tracting the226Ra content from the total:and if226Ra and223Raare low,224Ra may be determined directly.The determinationof a single isotope in a mixture is less precise than if it occurredalone.6.Interferences6.1 A barium content in the sample exceeding 0.2 mg willbias chemical yield high and lead to falsely low sample results.6.2 The presence of suspe