1、Designation: D 7283 06Standard Test Method forAlpha- And Beta- Activity in Water By Liquid ScintillationCounting1This standard is issued under the fixed designation D 7283; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year o
2、f last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method covers the measurement of grossalpha- and beta- activity concentrations in a homogeneouswater samp
3、le. It is applicable to alpha emitters with activityconcentration levels above 0.037 Bq/L (1 pCi/L) and betaemitters with activity concentration levels above 0.15 Bq/L (4pCi/L). This test method is not applicable to samples contain-ing radionuclides that are volatile under conditions of theanalysis.
4、1.2 This test method may also be used for the directmeasurement of gross alpha- and beta- activity concentrationsin homogeneous water samples with alpha emitter activityconcentration levels above 1.8 Bq/L (50 pCi/L) and betaemitter activity concentration levels above 3.7 Bq/L (100pCi/L).1.3 This tes
5、t method was tested using a single-operator test.2Round-robin testing is currently in progress on this testmethod.1.4 Standard methods under the jurisdiction of ASTM Com-mittee D19 may be published for a limited time preliminary tothe completion of full collaborative study validation. Suchstandards
6、are deemed to have met all other D19 qualifyingrequirements but have not completed the required validationstudies to fully characterize the performance of the TestMethod across multiple laboratories and matrices. Preliminarypublication is done to make current technology accessible tousers of standar
7、ds, and to solicit additional input from the usercommunity.1.5 The values stated in SI units are to be regarded asstandard. No other units of measurement are included in thisstandard.1.6 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is there
8、sponsibility 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.2. Referenced Documents2.1 ASTM Standards:3D 1129 Terminology Relating to WaterD 1125 Test Methods for Electrical Conductivity and R
9、e-sistivity of WaterD 1193 Specification for Reagent WaterD 1890 Test Method for Beta Particle Radioactivity ofWaterD 1943 Test Method for Alpha Particle Radioactivity ofWaterD 3370 Practices for Sampling Water from Closed ConduitsD 3648 Practices for the Measurement of RadioactivityD 3856 Guide for
10、 Good Laboratory Practices in Laborato-ries Engaged in Sampling and Analysis of WaterD 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 Ground Water Sampling forEnvir
11、onmental Site Characterization2.2 Other Standards and PublicationsEPA 900.0 Gross Alpha and Gross Beta Radioactivity inDrinkingWater, from Prescribed Procedures for Measure-ment of Radioactivity in Drinking Water (EPA-600/4-80-032)4Standard Methods 7110C Coprecipitation Method forGross Alpha Radioac
12、tivity in Drinking Water5Standard Methods 8010E Table 8010: Recommended Com-position for Reconstituted Fresh Water51This 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 a
13、pproved Dec. 15, 2006. Published January 2007.2Wong, C. T., Soliman, V. M., and Perera, S. K., Journal of Radioanalytical andNuclear Chemistry, Vol. 264, No. 2, 2005, pp. 357363.3For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org.
14、For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.4Available from United States Environmental Protection Association (EPA),Ariel Rios Bldg., 1200 Pennsylvania Ave., NW, Washington, DC 20460, http:/www.epa.gov.5Available from American
15、 Water Works Association (AWWA), 6666 W. QuincyAve., Denver, CO 80235, http:/www.awwa.org.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.ISO 9696 Water QualityMeasurement of Gross AlphaActivity in Non-saline WaterThick Source Method
16、63. Terminology3.1 Definitions of Terms Specific to This Standard:3.1.1 alpha-to-beta spillover, nin the measurement ofradioactivity, that fraction of alpha particles emitted by asource which are misclassified as beta particles.3.1.2 alpha particle detection effciency, nin the measure-ment of radioa
17、ctivity, that fraction of alpha particles emitted bya source which are identified as alpha particles by the counter.3.1.3 beta-to-alpha spillover, nin the measurement ofradioactivity, that fraction of beta particles emitted by a sourcewhich are misclassified as alpha particles.3.1.4 beta energy, max
18、imum, nthe maximum energy ofthe beta particle energy spectrum produced during beta decayof a given radionuclide.3.1.4.1 DiscussionSince a given beta emitter may decayto several different nuclear energy levels of the progeny, morethan one maximum energy may be listed for a given radionu-clide.3.1.5 b
19、eta particle detection effciency, nin the measure-ment of radioactivity, that fraction of beta particles emitted bya source which are identified as beta particles by the counter.3.1.6 detector background, nin the measurement of radio-activity, the counting rate resulting from factors other than ther
20、adioactivity of the sample and reagents used.3.1.6.1 DiscussionDetector background varies with thelocation, shielding of the detector, and the electronics; itincludes cosmic rays, contaminating radioactivity, and elec-tronic noise.3.1.7 figure of merit, na numerical quantity based on oneor more char
21、acteristics of a system or device that represents ameasure of efficiency or effectiveness. Generally calculated asthe square of the efficiency divided by the background.3.1.8 homogeneous water sample, nwater in which thealpha and beta activity is uniformly dispersed throughout thevolume of water sam
22、ple and remains so until the measurementis completed or until the sample is evaporated or precipitatingreagents are added to the sample.3.1.9 reagent background, nin the measurement of radio-activity of water samples, the counting rate observed when asample is replaced by mock sample salts or by rea
23、gentchemicals used for chemical separations that contain noanalyte.3.1.9.1 DiscussionReagent background varies with thereagent chemicals and analytical methods used and may varywith reagents from different manufacturers and from differentprocessing lots.3.2 DefinitionsFor definitions of terms used i
24、n this testmethod, refer to Terminology D 1129. For terms not defined inthis test method or in Terminology D 1129, reference may bemade to other published glossaries.4. Summary of Test Method4.1 The test sample is reduced by evaporation, transferred toa scintillation vial and mixed with a suitable l
25、iquid scintillationcocktail. Gross alpha- and beta- activity concentrations aremeasured simultaneously by liquid scintillation using alpha/beta discrimination. By optimizing the alpha/beta discrimina-tor, a high efficiency of alpha- and beta- particle detection canbe achieved with acceptable misclas
26、sification of beta particlesinto the alpha multi-channel analyzer (MCA) and alpha par-ticles into the beta MCA. The alpha- and beta-particle efficien-cies and crosstalk calibrations of the liquid scintillation systemare determined by using known activities of established refer-ence nuclides in test
27、sources having residual solids content andcocktail-solvent ratio comparable to that of the test samples.Some commonly employed reference standardsinclude241Am,239Pu,230Th, natural isotopic abundance ura-nium (234U,235U, and238U),90Sr/90Y, and137Cs. Results arereported in activity units equivalent al
28、ong with the referenceradionuclide (e.g., Bq/L gross alpha equiv.230Th).4.2 When low detection limits are not required, an aliquantof the sample is mixed directly with a suitable liquid scintil-lation cocktail for analysis.5. Significance and Use5.1 This test method is intended for the measurement o
29、fgross alpha- and beta-activity concentrations in the analyses ofenvironmental and drinking waters.5.2 This test method is also applicable to the direct analysisof gross alpha- and beta-activity concentrations in water whenlow detection limits are not required. Direct analysis providesa rapid method
30、 for determination of gross alpha- and beta-activity concentrations when low detection limits are notrequired.5.3 This test method is not capable of discriminating amongalpha emitting radionuclides or among beta emitting radionu-clides. Those intending to identify and quantify specific radio-nuclide
31、s should use test methods specific to the radionuclidesof interest.5.4 This test method may not be cited as a method for thedetermination of gross alpha- or beta-activity concentrations ina solid/soil matrix or the acid digestate of the same. The use ofthis test method for such applications brings t
32、he potential forserious bias and incomparability of results dependent on themanner of sample preparation or treatment, or both.6. Interferences6.1 The counting efficiencies for both the alpha and betacomponents are dependent on the energy of the alpha- orbeta-emitter chosen to determine the calibrat
33、ion coefficient.Biases may occur if the energies of the alpha- or beta-particleemitting nuclides in the test sample differs significantly fromthose used to determine the respective counting efficiencies.Best results are obtained when the radionuclide composition ofthe sample is known and the calibra
34、tion radionuclide isselected to match as closely as possible the energy of thesample radionuclide.6.2 The use of137Cs/137mBa as a calibration standard forsamples containing radionuclides other than137Cs may intro-duce a low bias in the analytical results unless there is a6Available from Internationa
35、l Organization for Standardization (ISO), 1 rue deVaremb, Case postale 56, CH-1211, Geneva 20, Switzerland, http:/www.iso.ch.D7283062correction for conversion electron emissions. The conversionelectrons from the137mBa progeny are detected by liquidscintillation yielding greater than 100 % detection
36、efficiencyfor the137Cs/137mBa calibration standard.6.3 When using uranium as a calibration standard theisotopic abundance of each of the isotopes (234U,235U,and238U) must be known to accurately determine the standardactivity concentration. Many uranium standards used for massmeasurements are deplete
37、d uranium. Natural isotopic abun-dance uranium and depleted uranium standards contain short-lived decay progeny (234Th,234mPa) which interfere with thespillover calibration unless they are removed immediately priorto calibration.6.4 Radon is a noble gas, and therefore easily emanatesfrom most matric
38、es. If the radon progeny of the uranium(222Rn), thorium (220Rn), and actinium (219Rn) series emanateprior to decaying, transient equilibrium is disrupted. EPA 900.0recognizes this disruption by suggesting a delay of 72 h beforethe prepared sample is counted for gross alpha. Other pub-lished methods
39、such as Standard Methods 7110C provide for ashorter delay of 3 h. This test method advises that any suchdelay period used by the laboratory be based on the measure-ment quality objectives inherent in the intended data use (see11.7).6.5 Radionuclides may be present in the sample in disequi-librium wi
40、th their parent radionuclides. Many factors, includ-ing preferential dissolution from the natural matrix in whichthe parent radionuclide occurs can cause this disequilibrium.Where these radionuclides have a half-life on the order of a fewdays or shorter, the time elapsed between sampling and thebegi
41、nning of sample counting will tend to bias the final resultlow. In those cases the measurement quality objectives inherentin the intended data may dictate the maximum time betweensample collection and the beginning of sample counting. Thelaboratory should be aware of such requirements and beprepared
42、 to comply with them.6.6 Radionuclides incorporated in volatile compounds arelost during the conduct of this test method. These includetritium in HTO or14C in the carbon dioxide formed during theaddition of acid. The pertechnetate ion (TcO42) is an exampleof a radionuclide which may be lost through
43、semi-volatility.The Measurement Quality Objectives should address the po-tential loss of such radionuclides and provide direction for theirquantification by specific methods.6.7 When counting gross alpha- and beta-activity by a liquidscintillation counter using alpha/beta discrimination, somepulses
44、resulting from alpha particles are misclassified as betaparticles and some pulses resulting from beta particles aremisclassified as alpha particles. The “spillover” characteristicsare determined during the calibration of the specific instrumentbeing used.6.8 Quenching of the photon output in the liq
45、uid scintilla-tion cocktail reduces detection efficiency and introduces addi-tional uncertainty in spillover corrections. Quenching is causedby molecular species in the sample and cocktail mixture thatreduce the intermolecular transfer of energy or absorb emittedvisible and UV photons prior to detec
46、tion. This test methoddescribes the use of an external standard source to minimizethe effects of quenching.6.9 The presence of solid particles in the scintillationcocktail may lead to erroneous results. This test methodrequires complete dissolution of the sample prior to addition ofthe scintillation
47、 cocktail.6.10 The sample aliquant/scintillation cocktail mixture ratioshould be within the cocktail manufacteurers recommenda-tions to insure a homogeneous mixture. If the sample aliquant/scintillation cocktail mixture forms two phases, repeat theanalysis with a different sample aliquant/scintillat
48、ion cocktailmixture/ratio.6.11 The exterior of the vials must be free of dirt, markings,and fingerprints.6.12 Dark adapting of scintillator solutions is dependentupon the fluor, the instrument and the lighting conditions of thecount room. Evaluation of these parameters for the adaptationto the darkc
49、onditions is necessary for counting optimization.6.13 Samples and standards should be counted with thesame instrument operating parameters including temperature.For refrigerated instruments, time should be allowed for thesamples to cool to the operating temperature of the instrument.Be aware of the potential for phase separation when coolingprepared samples.7. Apparatus7.1 Liquid Scintillation vials, approximately 20 mL,oflow-potassium glass are recommended.7.2 Electric hot plate.7.3 Glassware.7.4 Transfer pipettes.7.5 Liquid scintillation counting system, co
