ASTM_D_7168_-_11e1.pdf

Designation:D7168111Standard Test Method for99Tc in Water by Solid Phase Extraction Disk1This standard is issued under the fixed designation D7168;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.1NOTEAdded research report footnote to Section 16 editorially in June 2013.1.Scope1.1 This test method describes a solid phase extraction(SPE)procedure to separate99Tc from environmental watersamples(thatis,non-processandeffluentwaters).Technetium-99 beta activity is measured by liquid scintillationspectrometry.1.2 This test method is designed to measure99Tc in therange of approximately 0.037 Bq/L(1.0 pCi/L)or greater for aone litre sample.1.3 The values stated in SI units are to be regarded asstandard.Values given in parentheses are provided for infor-mation purposes only.1.4 This method has been used successfully with tap water.It is the users responsibility to ensure the validity of this testmethod for samples larger than 1 L and for waters of untestedmatrices.1.5 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 Section 9.2.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 ConduitsD4448 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 CharacterizationD7282 Practice for Set-up,Calibration,and Quality Controlof Instruments Used for Radioactivity Measurements3.Terminology3.1 DefinitionsFor definitions of terms used in this testmethod,refer to Terminology D1129.4.Summary of Test Method4.1 Ameasured aliquant of sample is transferred to a beaker.Hydrogen peroxide is added to facilitate the formation of theextractable pertechnetate ion.The sample may be heated tooxidize organics if such are suspected to be present.The entiresample is passed through a technetium-selective SPE disk ontowhich the pertechnetate is adsorbed.The disk is transferred toa liquid scintillation vial,cocktail added,and the contents wellmixed.The beta emission rate of the sample is determined byliquid scintillation spectrometry.Chemical yield correctionsare determined by the method of standard additions.4.2 Minor differences in processing between ExtractionChromatographic Resin Discs and PTFE Membrane Disks areaddressed in Variations A and B of the method.5.Significance and Use5.1 This method has not been evaluated for all possiblematrices.Method suitability should be determined on specificwaters of interest.6.Interferences6.1 Suspended materials must be removed by filtration orcentrifuging prior to processing the sample.Suspended par-ticulate matter in the sample will be physically trapped in partor in whole on or in the SPE extraction material.This may leadto potential inclusion of radionuclide bearing solids or to signalquenching in the liquid scintillation measurement.6.2 Technetium-99 activity in the sample may overwhelmthe signal from the99Tc spike addition and interfere withaccurate determination of chemical yield.Samples for which1This 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 May 15,2011.Published July 2011.Originallypublished in 2005.Last previous edition published 2005 as D7168 051.DOI:10.1520/D7168-11E01.2For 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 the unspiked sample count rate exceeds 50%of the spikedsample count rate should be reprepared with an appropriatelyadjusted aliquant and spike addition levels to minimize contri-butions to uncertainty in the determination of the chemicalyield.6.3 Organic compounds present in significant quantities inthe sample may degrade the extraction performance of the SPEdisk or may lead to elevated levels of quench during liquidscintillation analysis.After the addition of hydrogen peroxide,the sample may be heated to destroy trace organic matter in thesample.If organic components are present i