1、Designation: D5072 091Standard Test Method forRadon in Drinking Water1This standard is issued under the fixed designation D5072; 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 ind
2、icates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1NOTEEditorial corrections were made throughout in May 2014.1. Scope1.1 This test method covers the measurement of radon indrinking water in concentrations above 2 Bq/L.1.2
3、 This test method may be used for absolute measure-ments by calibrating with a226Ra standard or for relativemeasurements by comparing the measurements made witheach other.1.3 This test method is used successfully with drinkingwater samples and Type III reagent water conforming toSpecification D1193.
4、 It is the users responsibility to ensure thevalidity of this test method for waters of untested matrices.1.4 The values stated in SI units are to be regarded asstandard. No other units of measurement are included in thisstandard.1.5 This standard does not purport to address the safetyconcerns, if a
5、ny, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety andhealth practices and determine the applicability of regulatorylimitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D1129 Terminology Relating to WaterD1193 Specificatio
6、n 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 RadioactivityD3856 Guide for Management Systems in LaboratoriesEngaged in Analysi
7、s of WaterD4448 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 Qual
8、ity Controlof Instruments Used for Radioactivity Measurements2.2 Other Documents:Multi-Agency Radiological Laboratory Analytical ProtocolsManual EPA402-B-04-001A, NUREG1576, NTISPB2004-105421, July 2004.3. Terminology3.1 DefinitionsFor definitions of terms used in this testmethod, refer to Terminolo
9、gy D1129. For terms not defined inthis test method or in Terminology D1129, reference may bemade to other published glossaries.4. Summary of Test Method4.1 This test method is based on the scintillation countingof222Rn and its progeny.4.2 In a glass liquid scintillation vial, an aliquot of unaerated
10、water is drawn into a syringe then gently injected beneath 10mL of a suitable liquid scintillation cocktail that does notcontain an emulsifier. The vials are capped, shaken, andallowed to stand 3 hours prior to counting to permit darkadaptation and buildup of short-lived radon progeny. Radon-222 con
11、tained in the sample is selectively partitioned into thescintillation cocktail. The sample is counted using a liquidscintillation counting system optimized for detection of222Rnactivity.5. Significance and Use5.1 The most prevalent of the radon isotopes in groundwater is222Rn. This isotope presents
12、the greatest health riskcompared to the other naturally occurring radon isotopes ifingested via the water pathway.6. Interferences6.1 Other radionuclides soluble in the scintillation cocktailmay interfere. High energy beta/gamma emitters, even thoughthey are not soluble in the scintillation mix, may
13、 also interfere.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 Feb. 1, 2009. Published March 2009. Originallyapproved in 1992. Last previous edition appro
14、ved in 1998 a D5072 98 which waswithdrawn November 2008 and reinstated in March 2009. DOI: 10.1520/D5072-09E01.2For 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 s
15、tandards Document Summary page onthe ASTM website.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1These interferences will cause a high bias if present in asignificant quantity. These interferences would be rare indrinking water sampl
16、es but may be observed in some cases.6.2 A reduced or increased counting efficiency may result ifsample quenching is significantly different than that of thecalibration standard.6.3 Scintillation stock cocktails and sample cocktail mixesmust be dark-adapted to prevent artificial excitation of fluors
17、which may lead to falsely elevated count rates which couldcompromise data quality.7. Apparatus7.1 Sampling Funnel.7.2 Tube, with standard faucet fitting.7.3 Disposable Syringe, 12 mL capacity, with 20 gauge, 38mm hypodermic needle.7.4 Glass Liquid Scintillation Vials, 20 mL capacity withpolyethylene
18、 inner seal cap liners.7.5 Liquid Scintillation Counter.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 the specifications of the Commit-tee on Analytical Reagents of the Am
19、erican Chemical Society,where such specifications are available.3Other grades may beused, provided it is first ascertained that the reagent is ofsufficiently high purity to permit its use without lessening theaccuracy of the determination.8.2 Purity of WaterUnless otherwise indicated, referencesto w
20、ater shall be understood to mean conforming to Specifi-cation D1193, Type III.48.3 Radioactive Purity of ReagentsRadioactive purityshall be such that the measured radioactivity of blank samplesdoes not exceed the calculated probable error of measurements.8.4 Radium-226 Solution Standard, traceable t
21、o a nationalstandards laboratory such as the National Institute of Standardsand Technology (NIST) or the National Physical Laboratory(NPL).8.5 Scintillation Cocktail Mix, without emulsifier. Toluenebased mix is acceptable.9. Safety9.1 Some scintillation cocktails can pose a significant healthhazard
22、if handled improperly. Refer to manufacturer instruc-tions for the safe use of these materials.10. SamplingNOTE 1Refer to Practices D3370 for applicable sampling instructions.Also see U.S. Environmental Protection Agency reports EPA 5205andEPA 6006.10.1 Attach the sampling funnel and tube to a fauce
23、t withthe standard faucet fitting.10.2 Slowly turn on the water and allow a steady stream toflow out of the funnel for approximately 2 min. This purges thetube and ensures a fresh sample.10.3 Reduce the flow of water and invert the funnel. Theflow should be adjusted to a level that does not causetur
24、bulence in the pool of water contained in the funnel. Allowexcess water to spill over one edge of the funnel.10.4 Examine the hose connection and tubing for airbubbles or pockets. If these are visible, raise or lower thefunnel until they are removed.11. Calibration and Standardization11.1 Add a know
25、n quantity of traceable226Ra standardsolution to a known volume of water.11.2 Prepare three222Rn calibration standards by combininga 10 mL aliquot of the226Ra standard solution with 10 mL ofscintillation cocktail in a 20 mL glass scintillation vial.Securely cap each vial and shake to mix the content
26、s.11.3 In liquid scintillation vials, prepare three backgroundsamples containing 10 mLof Type III reagent water and 10 mLof scintillation solution. Cap the vials and shake to mix thecontents.11.4 Allow approximately 30 days for buildup of radon (thatis, secular equilibrium with226Ra).11.5 Shake vial
27、 to transfer nearly all the radon to thescintillation mix phase (radon is highly soluble in the scintil-lation mix). The226Ra remains in the aqueous phase and,therefore, does not contribute significantly to the count rate.11.6 Allow for the buildup of short-lived radon progeny andfor dark-adapting b
28、y waiting 3 hours before counting.11.7 Count the standard samples for a counting periodsufficiently long to obtain a relative counting uncertainty of 1% (10 000 net counts minimum). Count background samples atleast as long as the test samples.11.8 Calculate the calibration factor (CF) as in accordan
29、cewith 13.1.12. Procedure12.1 Clean scintillation vials with alcohol and add 10 mL ofscintillation cocktail.3Reagent Chemicals, American Chemical Society Specifications, AmericanChemical Society, Washington, DC. For Suggestions on the testing of reagents notlisted by the American Chemical Society, s
30、ee Annual Standards for LaboratoryChemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeiaand National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville,MD.4If this water is not aerated or degassified prior/subsequent to demineralization,radon background may be sub
31、stantial. This can happen if the lab uses RO, EDI oronly deminerialization resins for purification of their water.5EPA520/583027 Methods and Results of EPAs Study of Radon in DrinkingWater. Published December 1983. Available from U.S. Government Printing OfficeSuperintendent of Documents, 732 N. Cap
32、itol St., NW, Mail Stop: SDE,Washington, DC 20401, http:/www.access.gpo.gov.6EPA 600/287/082 Two Test Procedures for Radon in Drinking Water.Published March 1989. Available from U.S. Government Printing Office Superin-tendent of Documents, 732 N. Capitol St., NW, Mail Stop: SDE, Washington, DC20401,
33、 http:/www.access.gpo.gov.D5072 091212.2 Collect unaerated sample in accordance with Section10.12.3 Place the tip of the hypodermic needle approximately 3cm under the surface of the water in the funnel and withdrawa few millilitres of water and eject this water. Using thisprocedure, rinse the syring
34、e and hypodermic needle two orthree more times.12.4 Again, place the tip of the needle approximately 3 cmbelow the surface of the water and withdraw approximately 12mL.NOTE 2The water should be pulled into the syringe slowly to avoidextreme turbulence and collection of air bubbles. If large air bubb
35、les arenoticed in the syringe, the sample should be rejected and redrawn.12.5 Invert the syringe and slowly eject any small airbubbles and extra water. Retain precisely 10 mLof water in thesyringe.12.6 Remove the cap from a vial and carefully place the tipof the needle into the bottom of the liquid
36、scintillation solution.Slowly eject the water from the syringe into the vial.NOTE 3Water is injected under the liquid scintillation solution toprevent loss of radon from the sample. If the water is forced out of thesyringe with much pressure, it will cause turbulence in the solution andcould result
37、in loss of radon.12.7 Carefully withdraw the hypodermic needle from thevial and replace the cap. The cap should be tightly secured toprevent leakage. Shake the vial to mix the contents.12.8 Repeat the previous steps to obtain two separatealiquots from each sample.12.9 Load the samples into the liqui
38、d-scintillation countingsystem and after waiting for 3 h, count at least 50 minutes.12.10 After dark-adapting them, count a backgroundsample, consisting of 10 mLof water and 10 mLof scintillationsolution, and a standard radium-226 solution sample for 50 minat the beginning of counting and after ever
39、y ten drinking watersamples.13. Calculation13.1 Calibration Factor, CF:CF 5CCS2 CB!ACS(1)where:CCS= calibration standard count rate, counts per second(s1) (as prepared in 11.2),CB= average background sample count rate (s1) (as pre-pared in 11.3), andACS= calibration standard226Ra activity, Bq.13.2 S
40、ample Activity, ACCalculate the radon activity con-centration in the sample as follows. First calculate the net countrate in counts per second:Rn5 Ra2 Rb(2)Then calculate the activity concentration of radon in thesample, in becquerels per litre (Bq/L), using the followingequation:AC 5RnCF 3D 3Va(3)w
41、here:AC = activity concentration of222Rn (Bq/L),Ra= Sample count rate (s1),Rb= background count rate (s1),Rn= net count rate (s1),CF = calibration factor calculated as in Eq 1,D = decay correction factor D=eln(2) T/t,Va= volume of sample analyzed (0.010 L),T = time in days from collection time to mi
42、dpoint ofcounting time, andt= half-life of222Rn, 3.82 d.13.3 Estimate the square of the standard uncertainty of Rnasfollows:u2Rn! 55J 3Rn12Rbt, if Rn.0Ra1Rbt, if Rn#0(4)where:t = counting time of the sample and background (s), andJ = index of dispersion for the net counts produced by222Rnand its pro
43、geny.7If the counting time t is 3000 s, then J is approximately equalto 1.83 if the counter is configured to count alpha radiationonly and J is approximately equal to 2.78 if it is configured tocount both alpha and beta radiation. For longer count timesestimate J as follows:J 5c51(i503cie2it1 2 e20t
44、(5)where the decay constants 0through 3are given by:0= 2.098 106s1,1= 0.003 727 s1,2= 0.000 431 s1, and3= 0.000 581 s1.and where the coefficients c0through c5are given either by:c0= 3.0060503c1= 0.00038339968c2= 0.026908241c3= 0.015190995c4=0c5= 2.9939497if the counter is configured to count alpha r
45、adiation only, or by:c0= 5.0106487c1= 0.00020574781c2= 0.036387727c3= 0.015296013c4=0c5= 4.9893513if the counter is configured to count both alpha and betaradiation.7Lucas, H.F., Jr., and D.A. Woodward, Journal of Applied Physics, Vol. 35, pg.452, 1964.D5072 091313.4 The combined standard uncertaint
46、y of the radon activ-ity concentration can be estimated as follows:ucAC! 5=u2Rn!1Rn23 ur2CF!1ur2Va!1ur2D!CF 3D 3Va(6)where:uc(AC) = combined standard uncertainty of the radon activ-ity concentration (Bq/L),ur(CF) = relative standard uncertainty of the calibrationfactor CF,8Va= volume of sample analy
47、zed (0.010 L),ur(Va) = relative standard uncertainty of the volume (0.010L) of sample analyzed, andur(D) = relative standard uncertainty of the decay correc-tion D.13.5 The a priori minimum detectable radon activity con-centration (MDC) can be estimated by the following equation:MDC 52.71 3Jt14.65Rb
48、tCF 3D 3Va(7)where:MDC = minimum detectable radon activity concentration(Bq/L).13.6 The critical level Lcfor radon activity concentrationcan be calculated by the following equation:Lc52.33RbtCF 3D 3Va(8)where:Lc= critical level radon activity concentration (Bq/L).14. Precision and Bias914.1 The coll
49、aborative test conducted on this test methodincluded 15 laboratories each with one operator. Three activitylevels between 60 Bq/L and 2454 Bq/L were tested with threereplicates per level.The determination of the precision and biasstatements were made in accordance with Practice D2777.14.2 These collaborative test data were obtained usingreagent grade water. For other matrices, these data may notapply.14.3 The overall and single operator precision have beenfound to vary with level in a manner according to Table 1.14.4 The
