1、Designation: D 7168 051Standard Test Method for99Tc in Water by Solid Phase Extraction Disk1This standard is issued under the fixed designation D 7168; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A nu
2、mber in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1NOTEFootnote 7 was updated editorially in February 2009.1. Scope1.1 This test method describes a solid phase extraction(SPE) procedure to separate99
3、Tc from environmental watersamples (that is, non-process and effluent waters).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 value
4、s 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
5、 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 u
6、se. For specific hazardstatements, see Section 9.2. Referenced Documents2.1 ASTM Standards:2D 1129 Terminology Relating to WaterD 1193 Specification for Reagent WaterD 2777 Practice for Determination of Precision and Bias ofApplicable Methods of Committee D19 on WaterD 3370 Practices for Sampling Wa
7、ter from Closed ConduitsD 4448 Guide for Sampling Ground-Water MonitoringWellsD 5847 Practice for Writing Quality Control Specificationsfor Standard Test Methods for Water AnalysisD 6001 Guide for Direct-Push Water Sampling for Geoen-vironmental Investigations3. Terminology3.1 DefinitionsFor definit
8、ions of terms used in this testmethod refer to Terminology D 1129.4. 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 s
9、uspected 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 scintilla
10、tion 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 be
11、en 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
12、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 withaccura
13、te determination of chemical yield. Samples for whichthe unspiked sample count rate exceeds 50 % of the spikedsample count rate should be reprepared with an appropriately1This test method is under the jurisdiction of ASTM Committee D19 on Waterand is the direct responsibility of Subcommittee D19.04
14、on Methods of Radiochemi-cal Analysis.Current edition approved June 1, 2005. Published June 2005.2For 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 Docum
15、ent Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.adjusted aliquant and spike addition levels to minimize contri-butions to uncertainty in the determination of the chemicalyield.6.3 Organic compounds
16、 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 organi
17、c components are present in the sample whichmay survive the peroxide digestion, these may be removedwith an appropriate organic removal resin or disk (such asAmberchrom resin or disk) prior to passing the sample throughthe extraction chromatographic resin disc.6.4 The disk may retain tritium-labeled
18、 compounds. Settingthe99Tc counting window above the maximum energy for thetritium beta particle will eliminate potential tritium interfer-ence.6.5 Elevated levels of nitrates ( 10 000 ppm) will interferewith uptake of99Tc.6.6 The higher energy region above the maximum energyfor99Tc should be monito
19、red to help identify cases of signifi-cant actinide interference.6.7 Elevated levels of radionuclides present in anionic formsuch as iodate, iron (III) and antimony may interfere withmeasurement of technetium and lead to a positive bias insample results. Significantly elevated levels of actinides(es
20、p.234Th decay progeny of uranium) when present in thesample may cause a high bias in the reported99Tc activity.Manufacturer specific recommendations about interferencesshould be taken into consideration when determining theapplicability of this method for a given matrix.7. Apparatus7.1 Filtering App
21、aratus, 47-mm diameter filter apparatus asrecommended by the SPE manufacturer.7.2 Liquid Scintillation Counter, with multiple energy re-gion of interest (ROI) capabilities.7.3 Scintillation Vials, 20-mL vials, low potassium glass orplastic, exhibiting suitable optical reproducibility so as not tocau
22、se erratic results between samples.8. Reagents and Materials8.1 Purity of ReagentsReagent grade chemicals shall beused in all tests. Unless otherwise indicated, it is intended thatall reagents shall conform to specifications of the Committeeon Analytical Reagents of the American Chemical Society.3Ot
23、her grades may be used, provided it is first ascertained thatthe reagent is of sufficiently high purity to permit its usewithout lessening the accuracy of the determinations.8.2 Purity of WaterUnless otherwise indicated, referencesto water shall be understood to mean reagent water conformingto Speci
24、fication D 1193, Type III.8.3 Radioactive PurityRadioactive purity shall be suchthat the measured radioactivity of blank samples does notexceed the calculated probable error of the measurement.8.4 Technetium-Specific Solid Phase Extraction (SPE) Disksor Membranes (Extraction Chromatographic Resin Di
25、scs4orPTFE Membrane Disks4,5).8.5 Hydrochloric Acid, 0.5MAdd 42 mL concentratedHCl to 400 mL of reagent water. Dilute to 1 L with water.8.6 Nitric Acid, concentrated.8.7 Hydrogen Peroxide,30%.8.8 Technetium-99 as pertechnetate in water or dilute basesolution, traceable to a national standards body (
26、such as NISTin the U.S.).8.9 Liquid Scintillation CocktailCommercially preparedLSC cocktail or equivalent.4,69. Hazards9.1 Use extreme caution when handling all acids. They areextremely corrosive, and skin contact could result in severeburns.9.2 When diluting concentrated acids, always use safetygla
27、sses and protective clothing, and add the acid to the water.10. Sampling10.1 Collect a sample in accordance with Practice D 3370,D 4448 or D 6001.11. Preservation11.1 Preservation of samples being analyzed for99Tc is notrequired.11.1.1 Samples may be preserved by freezing. Allowsamples to come to am
28、bient temperature prior to processing.11.1.2 Samples may be processed if they have been previ-ously preserved to pH less than 2 with nitric or hydrochloricacid. It is noted that high concentrations of nitric acid willadversely affect chemical yield.Although yield corrections willcorrect for losses,
29、better results may be obtained by usingunpreserved samples.12. Calibration12.1 The fractional detector efficiency (Tc) is determined asoutlined in subsequent steps.12.1.1 Prepare triplicate calibration samples adding at least20 Bq (540 pCi) of traceable99Tc in the pertechnetate form toeach of three
30、100 mL portions of reagent water. Each of thethree samples is processed using either method variation (A orB), as appropriate.12.1.2 Collect the effluents from the three calibrationsamples. Process the composited solution according to the3Reagent Chemicals, American Chemical Society Specifications,
31、AmericanChemical Society, Washington, DC. For suggestions on the testing of reagents notlisted by the American Chemical Society, see Annual Standards for Laboratory andNational Formulary, U.S. Pharmaceutical Convention, Inc. (USPC), Rockville,MD.4The sole source of supply of the Eichrom TEVAt Discs
32、known to thecommittee at this time is Eichrom Technologies, Inc., Darien, IL. If you are awareof alternative suppliers, please provide this information to ASTM InternationalHeadquarters. Your comments will receive careful consideration at a meeting of theresponsible technical committee,1which you ma
33、y attend.53M Emporey Tc Rad Disks (3M, St. Paul, MN) have been found satisfactoryfor this purpose.6Ultima Goldy LLT (Perkin Elmer Life and Analytical Sciences, 710 Bridge-port Avenue, Shelton, CT 06484-4794) has been found satisfactory for this purpose.D71680512method to verify that greater than 99
34、% of the technetium wasretained by the SPE material in the calibration runs.12.1.3 An analyte-free aliquant of 100 mL reagent water isalso processed as a calibration or instrument blank.12.1.4 Count the three vials containing the calibrationsamples and the blank in a liquid scintillation counter for
35、 a timesufficient to amass greater than 10 000 counts for each of thecalibration standards.12.1.5 Calculate the99Tc Detector Efficiency (Tc) for eachof the three vials:Tc5Rg2 RcbAc(1)where:Rg= gross count rate of the vial in the99Tc count windowin counts per second,Rcb= count rate of the calibration
36、 blank associated withthe efficiency measurement in the99Tc count win-dow in counts per second, andAc= activity of standard99Tc added to each vial (Bq).12.2 Calculate the average, Tc, and the relative standarddeviation, sr(Tc), for the three efficiency values. The relativestandard deviation of these
37、 parameters is used to estimate therelative standard uncertainty of the average efficiency, ur(Tc),as follows:urTc! 5sr2Tc!31 ur2Ac! (2)where:ur(Ac) = relative standard uncertainty of the activity ofstandard99Tc added to each vial.12.3 Acalibration blank consisting of reagent water shall beprocessed
38、 and analyzed with each batch of samples to deter-mine the background count rate in counts per second (Rb)tobeused for the calculation of sample results.13. ProcedureNOTE 1To minimize the risk of cross-contamination while ensuringreproducibility between the sample and its spiked duplicate, each aliq
39、uant-spiked aliquant pair should be run simultaneously and in parallel, usingseparate dedicated filtration apparatus.NOTE 2The sample aliquant is typically 1 L but depending on theactivity present and the required detection limit for the analysis, this mayvary from 0.1 to several litres.NOTE 3A repr
40、esentative instrument blank (vial, cocktail and blankdisk) is counted with each batch to determine the background count rateto be subtracted from each measurement (Rbin Eq 3). If the instrumentblank is to be reused, the user should determine its stability and shelf-life.13.1 Method Variation AFor us
41、e with Extraction Chro-matographic Resin Discs:13.1.1 For each sample to be processed, transfer duplicate 1L aliquants of sample to each of two beakers.13.1.2 Acidify samples to pH 2 with nitric acid, if not donepreviously.13.1.3 Add a known quantity (20 Bq) of a traceable99Tcsolution to the second
42、aliquant of the sample which is labeledas the spiked sample. (See section 6.2 for comment onappropriate spiking level.)13.1.4 Add 10 mL of 30 % H2O2to each sample whilestirring.13.1.5 If the presence of organic interferences is suspected,heat the sample on a hotplate at approximately 80C for about1
43、hour or until any visible reaction has subsided. Allow thesample to cool to ambient temperature before proceeding withsubsequent steps.13.1.6 Using forceps, carefully position a disc on the filterstand. Secure the funnel reservoir over the disc.13.1.7 Precondition the disc by allowing 25 mL of water
44、 topass through the disc by gravity.13.1.8 Add the sample to the funnel reservoir and allow topass through the disc by gravity flow (nominal flow rate shouldnot exceed 100 mL/min).13.1.9 Rinse the disc with 25 mL of 0.5M HCl.13.1.10 Rinse the disc with 100 mL of water.13.1.11 Apply vacuum to the fil
45、tration apparatus to removeresidual liquid from the disc.13.1.12 Detach the reservoir from the filter apparatus.13.1.13 Using forceps, remove and carefully roll the discand transfer to a scintillation vial.13.1.14 Add 15 mL of liquid scintillation cocktail.13.1.15 Cap and shake the contents of the v
46、ial, to allow thedisc to disintegrate. A vortex mixer may be used.13.1.16 Count the sample in a liquid scintillation counterusing an optimized energy window within the range of 20 to292 keV for a period of time adequate to achieve the requireddetection limit.13.2 Method Variation BFor use with PTFE
47、ExtractionMembranes:13.2.1 For each sample to be processed, transfer duplicate 1L aliquants of sample to each of two beakers.13.2.2 Add a known quantity (20 Bq) of traceable99Tcsolution to the second aliquant of the sample which is labeledas the spiked sample. (See section 6.2 for comment onappropri
48、ate spiking level.)13.2.3 Add 10 mL of 30 % H2O2to each sample whilestirring.13.2.4 If the presence of organic interferences is suspected,heat the sample on a hotplate at approximately 80C forapproximately 1 hour or until any visible reaction has subsided.Allow the sample to cool to ambient temperat
49、ure beforeproceeding with subsequent steps.13.2.5 Using forceps, carefully position a disk on the filterstand. Secure the funnel reservoir over the disk.13.2.6 Connect the filtering apparatus to a vacuum source.13.2.7 Pass the sample through the disk at a nominal flowrate of 100 mL/min.13.2.8 Rinse the disk with 25 mL of 0.5M HCl.13.2.9 Rinse the disk with 100 mL of water.13.2.10 Detach the reservoir from the filter apparatus.13.2.11 Using forceps, remove and gently roll the disk andtransfer to a scintillation vial.13.2.12 Add 15 mL of liquid scint
