ASTM_D_4785_-_08_2013e1.pdf

Designation:D478508(Reapproved 2013)1Standard Test Method forLow-Level Analysis of Iodine Radioisotopes in Water1This standard is issued under the fixed designation D4785;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.1NOTEWarning notes were editorially updated throughout in June 2013.1.Scope1.1 This test method covers the quantification of low levelsof radioactive iodine in water by means of chemical separationand counting with a high-resolution gamma ray detector.Iodine is chemically separated from a 4-L water sample usingion exchange and solvent extraction and is then precipitated ascuprous iodide for counting.1.2 The values stated in SI units are to be regarded asstandard.The values given in parentheses are provided forinformation purposes only.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 specific hazardstatements,see 8.17,8.18,8.19,Section 9,and 13.2.11.2.Referenced Documents2.1 ASTM 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 RadioactivityD3649 Practice for High-Resolution Gamma-Ray Spectrom-etry of WaterD5847 Practice for Writing Quality Control Specificationsfor Standard Test Methods for Water AnalysisD3856 Guide for Management Systems in LaboratoriesEngaged in Analysis of Water3.Terminology3.1 DefinitionsFor definitions of terms used in this testmethod,refer to Terminology D1129.4.Summary of Test Method4.1 Sodium iodide is added as a carrier prior to performingany chemical separations.The samples undergo an oxidation-reduction process to ensure exchange between the carrier andthe radioactive iodide.Hydroxylamine hydrochloride and so-dium bisulfite are added to convert all the iodine to iodidewhich is then removed by anion exchange.Subsequent elutionof the iodide is followed by oxidation-reduction to elementaliodine.The elemental iodine is purified by solvent extraction,reduced to iodide,and precipitated as cuprous iodide.Thechemical recovery is determined from the recovery of theiodide carrier.5.Significance and Use5.1 This test method was developed for measuring lowlevels of radioactive iodine in water.The results of the test maybe used to determine if the concentration of several radioiso-topes of iodine in the sample exceeds the regulatory statutes fordrinking water.With a suitable counting technique,samplesize,and counting time,a detection limit of less than 0.037Bq/L(1 pCi/L)is attainable by gamma-ray spectroscopy.Thismethod was tested for131I.Other iodine radioisotopes shouldbehave in an identical manner in this procedure.However,other iodine radioisotopes have not been tested according toPractice D2777.The user of this method is responsible fordetermining applicability,bias,and precision for the measure-ment of other iodine radioisotopes using this method.5.2 This procedure addresses the analysis of iodine radio-isotopes with half-lives greater than 2 hours,which include121I,123I,124I,125I,126I,129I,130I,131I,132I,133I,and135I.6.Interferences6.1 Stable iodine in the sample will interfere with thechemical recovery determination.One milligram of ambientiodine would produce a bias of about 4%.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 June 15,2013.Published July 2013.Originallyapproved in 1988.Last previous edition approved in 2008 as D4785 08.DOI:10.1520/D4785-08R13E01.2For 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 International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 6.2 There are numerous characteristic iodine X-rays at andbelow 33.6 keV which are indicative of iodine,but not aspecific radioisotope of iodine.It is recommended that onlydiscreet gamma energy lines at and above 35.5 keV be used foridentification and quantification of iodine radioisotopes.7.Apparatus7.1 Analytical Balance,readable to 0.1 mg.7.2 Flexible Polyvinyl Chloride(PVC)Tubing,6.35 mm(14in.)outside diameter,1-m length.7.3 Gamma-Ray Spectrometry SystemHigh resolutiongamma spectrometer(high purity germanium or equivalent)with a