1、Designation: D 5811 00Standard Test Method forStrontium-90 in Water1This standard is issued under the fixed designation D 5811; 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 indi
2、cates 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 determination of radioac-tive90Sr in environmental water samples (for example, non-process and effluent waters) in the range of 0.03
3、7 Bq/L (1.0pCi/L) or greater.1.2 The values stated in SI units are to be regarded as thestandard. The values given in parentheses are for informationonly.1.3 This test method has been used successfully with tapwater. It is the users responsibility to ensure the validity of thistest method for sample
4、s larger than 1 L and for waters ofuntested matrices.1.4 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 o
5、f regulatory limitations prior to use. For specific hazardstatements, see Section 9.2. Referenced Documents2.1 ASTM Standards:D 1129 Terminology Relating to Water2D 1193 Specification for Reagent Water2D 1890 Test Method for Beta Particle Radioactivity ofWater3D 2777 Practice for Determination of Pr
6、ecision and Bias ofApplicable Methods of Committee D-19 on Water2D 3370 Practices for Sampling Water from Closed Con-duits2D 3648 Practices for the Measurement of Radioactivity33. Terminology3.1 DefinitionsFor definitions of terms used in this testmethod, refer to Terminology D 1129.4. Summary of Te
7、st Method4.1 This test method is based on the utilization of solidphase extraction of strontium from water samples with detec-tion of the radioactive strontium by gross beta gas proportionalcounting.4.2 An aliquant of the sample is measured into a beaker,strontium carrier added, digested with nitric
8、 acid, sorbed on anion exchange column, eluted, evaporated to dryness, dissolvedin nitric acid (8M), selectively sorbed on a solid phaseextraction column, eluted with dilute nitric acid, dried on aplanchet, and counted for beta radiation.5. Significance and Use5.1 This test method was developed to m
9、easure the concen-tration of90Sr in non-process water samples. This test methodmay be used to determine the concentration of90Sr in environ-mental samples.6. Interferences6.1 Significant amounts of stable strontium present in thesample will interfere with the yield determination. If it isknown or su
10、spected that natural strontium is present in thesample, blank sample aliquots to which no strontium carrier isadded shall be analyzed to determine the natural strontiumcontent. The amount of natural strontium contained in thesample shall be used to correct the yield.6.2 Strontium-89 present in the s
11、ample will cause a highbias in proportion to the89Sr/90Sr ratio. This technique is notapplicable when it is suspected or known that89Sr is present inthe sample.6.3 Strontium nitrate (Sr(NO3)2) is hygroscopic. Thischemical property may add uncertainty in the gravimetric yielddetermination.7. Apparatu
12、s7.1 Analytical Balance, 0.0001 g.7.2 Gas Proportional Beta Counting System, (1.0 cpmbeta), low background.7.3 Ion Exchange Columns, 10 mL resin capacity, glass oracid-resistant plastic.An attached reservoir of at least 50 mL isdesirable.1This test method is under the jurisdiction of ASTM Committee
13、D-19 on Waterand is the direct responsibility of Subcommittee D19.04 on Methods of Radiochemi-cal Analysis.Current edition approved July 10, 2000. Published October 2000. Originallypublished as D 5811 95. Last previous edition D 5811 95.2Annual Book of ASTM Standards, Vol 11.01.3Annual Book of ASTM
14、Standards, Vol 11.02.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.7.4 Planchets, stainless steel, 5.1 cm (2 in.) diameter with 6mm (14 in.) high outer lip.48. Reagents and Materials8.1 Purity of ReagentsReagent grade chemicals sha
15、ll 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.5Other grades may be used, provided it is first ascertained thatthe reagent is of sufficiently high purity to pe
16、rmit its usewithout lessening the accuracy of the determination. Reagentblanks shall be run with all determinations.8.2 Purity of Water Unless otherwise indicated, referenceto water shall be understood to mean reagent water conformingto Specification D 1193, Type III.8.3 Radioactive PurityRadioactiv
17、e purity shall be suchthat the measured radioactivity of blank samples does notexceed the calculated probable error of the measurement.8.4 Cation Exchange Resin,6100 to 200 mesh, hydrogenform.8.5 Nitric Acid (1 + 1)Combine one part by volumeconcentrated nitric acid, HNO3(sp gr 1.42) and one part byv
18、olume water. This solution is 8 M HNO3.8.6 Nitric Acid (1 + 159)Combine one part by volumeconcentrated nitric acid, HNO3(sp gr 1.42) and 159 parts byvolume water. This solution is 0.1 M HNO3.8.7 Nitric Acid (1 + 319)Combine one part by volumeconcentrated nitric acid, HNO3(sp gr 1.42) and 319 parts b
19、yvolume water. This solution is 0.05 M HNO3.8.8 Strontium Carrier (10 g/L)Preferably use 10 000 gSr/mLICPstandard.7Alternatively, dissolve 24.16 g strontiumnitrate (Sr (NO3)2) in water and dilute to 1 L. Use thefollowing procedure to standardize the prepared strontiumcarrier. Carefully pipet a 5.0 m
20、L portion of the strontiumcarrier solution onto a clean, dried, and tared planchet. Dry theplanchet under a drying lamp. Cool the planchet in a desiccatorand weigh. Divide the net weight by 10. This result is theamount of strontium nitrate actually added. Use an average ofthree values in the denomin
21、ator of the recovery equation in11.2 and 13.1. This value should be within 3 % of 12.08 mg/0.5mL.8.9 Strontium Extraction Chromatography Column,2mLbed volume.88.10 Strontium-90 Standardizing SolutionNational Insti-tute of Standards and Technology (NIST) traceable solutionwith less than 0.1 mg of sta
22、ble strontium per mL of finalsolution with a typical concentration range from 85 to 125Bq/mL.9. 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 safetyglasses and protecti
23、ve clothing, and add the acid to the water.10. Sampling10.1 Collect a sample in accordance with Practice D 3370.11. Calibration11.1 Prepare a set of three calibration samples according tothe calibration procedure outlined in the subsequent steps.11.2 Pipet 0.5 mL of strontium carrier into a small be
24、aker.11.3 Add 1 mL of NIST traceable90Sr solution and evapo-rate to near dryness on a hot plate.11.4 Redissolve the residual in 5 mL of nitric acid (8M).11.5 Follow the steps described in 12.10 through 12.22.11.6 Count to amass 10 000 counts in the counting period.Counting should be completed within
25、3hofcolumn elution.Record the time and date of the midpoint of this countingperiod as t2. Count each sample mount twice, once for this stephaving a counting date designated as t2and a second time asspecified below.11.7 Calculate the net count rate of the first count (cps2)bysubtracting the instrumen
26、t background count rate from thegross count rate.11.8 Store the calibration mount for at least 7 days to allowfor90Y ingrowth.11.9 Recount the calibration mount to amass 10 000 countsin a counting period. Record the time and date of the midpointof this count period as t3.11.10 Calculate the net coun
27、t rate of the second count (cps3)by subtracting the instrument background count rate from thegross count rate.11.11 Calculate the90Sr detection efficiency, ES, and the90Y detection efficiency, EY, for each calibration mount usingthe equations presented below. Calculate the mean and stan-dard deviati
28、on of the three ESrand EYvalues. Use the relativestandard deviation of these parameters to estimate the relativeuncertainty of the ingrowth efficiency factor, UIEof Eq 7.11.12 Effciency Calculations:90Sr detection efficiency ESrESr5RC2!3 IF2! 2 RC3!3 IF1!YSr3 AC2!3 IF22 IF1!#(1)90Y detection efficie
29、ncy EYEY5RC3!2 YSr3 AC2!3 ESr!YSr3 AC2!3 IF2(2)where:AC(2)= activity of90Sr in Bq at the time of the first countof the calibration mount,IF1= 1elY( t2t1)IF2= 1elY(t3t1)lY= decay constant for90Y (0.2595 d-1),9RC(2)= net count rate of calibration mount at first count, incounts per second,4Stainless st
30、eel planchets available commercially have been found satisfactory.5Reagent Chemicals, American Chemical Society Specifications, AmericanChemical Society, Washington, DC. For suggestions on the testing of reagents notlisted by the American Chemical Society, see Analar Standards for LaboratoryChemical
31、s, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeiaand National Formulary, U.S. Pharmaceutical Convention, Inc. (USPC), Rockville,MD.68 % cross-linked cation resin, analytical grade has been found satisfactory.7ICP Sr standard available commercially has been found satisfactory.8Stro
32、ntium resin column 2 mL resin bed volume consisting of an octanolsolution of 4,4(5)-bis (t-butyl-cyclohexano)-18-crown-6 sorbed on an inert poly-meric support is required.D 5811 002RC(3)= net count rate of calibration mount at secondcount, in counts per second,t1= date and time of90Y separation,t2=
33、date and time of midpoint of first count,t3= date and time of midpoint of second count.NOTE 1The time differences (t2 t1) and (t3 t1) shall be expressedin days.YSr= fractional chemical yield of strontium carrier (see Eq4).12. Procedure12.1 Add 0.5 mL of strontium carrier to a maximum of 1 Lof sample
34、.Add 1 mLof HNO3(8M) per 100 mLof sample andmix. Bring sample to a boil for 30 min and then cool.12.2 Prepare a cation exchange column containing 10 mLofcation exchange resin.12.3 Precondition the column by passing 50 to 55 mL ofHNO3(0.1M) through the column.12.4 Pass the sample through the column a
35、t a rate of notmore than 5 mL/min.12.5 Rinse the column with 25 to 30 mL of HNO3(0.1M).12.6 Properly dispose of the feed and rinse.12.7 Elute the strontium (and other cations) with 50 mL ofHNO3(8M) into a 150 mL beaker.12.8 Evaporate the eluate to near dryness on a hot plate in afume hood. The resid
36、ue will dissolve more easily in the nextstep if the evaporation is stopped just as the sample starts to godry.12.9 Dissolve the salts in 5 mL of HNO3(8M). If necessary,cover with a watchglass and heat gently.12.10 Prepare a strontium extraction chromatography col-umn by removing the bottom plug and
37、the cap. Press the topfrit down snugly to the resin surface using a glass rod (orequivalent) and let the water drain out. Add 5 mL ofHNO3(8M) and let the solution drain by gravity.12.11 Carefully transfer the sample solution to the reservoirof the column.Add half and let the solution drain before ad
38、dingthe second half.12.12 Rinse the beaker with 3 mLof HNO3(8M) and add tothe column after the feed has passed through.12.13 Repeat 12.12.12.14 Rinse the column with 10 mL of HNO3(8M).12.15 Record the end time of the last rinse as the 90yseparation (start of 90yingrowth, t1).12.16 Elute the strontiu
39、m with two 5 mL portions of HNO3(0.5M) into a plastic container (for example, a liquid scintil-lation counting vial).12.17 Clean a planchet with a paper towel moistened withalcohol. Wipe the planchet and let it dry.12.18 Weigh the planchet to 0.0001 g and record the weight.12.19 Place the planchet u
40、nder a heat lamp in a fume hood.12.20 Evaporate the strontium eluate (see 12.16) onto theplanchet by adding small portions (approximately 3 mL) to theplanchet and allowing each portion to evaporate to neardryness between additions.12.21 After all the solution has dried, cool the planchet toroom temp
41、erature and reweigh the planchet. Record the weightto 0.0001 g.12.22 Count the sample as soon as possible after preparationon a low background beta gas proportional counting system.Also count an empty planchet for an equal length of time tomeasure the instruments background count rate. (See TestMeth
42、od D 1890 and Practices D 3648.)13. Calculation13.1 Strontium-90 Radioactivity Concentration (ACSr):ACSrBq/L!5Ra RbIE 3 Va3 YSr3 e2lSrt1t0!(3)YSr5mg SrNO3!2sample aliquant! mg SrNO3!2reagent blank!mg Sr carrier added as nitrate!(4)IE 5 ESr1 EY1 2 e2lytmtl! (5)where:ESr= the mean of the values calcul
43、ated using Eq 1,EY= the mean of the values calculated using Eq 2,IE = ingrowth efficiency factor,lSr= decay constant for90Sr (6.594E5d-1),9lY= decay constant for90Y (0.2595 d-1),9Ra= count rate of sample aliquant, in counts per second,Rb= count rate of instrument background, in counts persecond,t0=
44、date and time of sample collection,t1= date and time of90Y separation, andtm= midpoint of count of sample aliquant (date and time).NOTE 2The time differences (t1t0) and (tmt1) shall be expressedin days.Va= volume of sample aliquant, in litres, andYSr= fractional chemical yield (recovery) of strontiu
45、mcarrier.13.2 The sample aliquant has an uncertainty in its net countrate (“counting uncertainty”). The uncertainty in the90Srradioactivity concentration in the sample from the countinguncertainty, UR, is given at a 68 % confidence level by:URBq/L!5= Ra1 Rb=taIE 3 Va3 YSr3 e2lSrtl t0!(6)where:ta= co
46、unt duration, in seconds, of the sample aliquant,and the other terms are as defined in 13.1.13.3 Total Propagated Uncertainty (TPU):TPU Bq/L!5ACSrSURACSTD21 UIE21 UVa21 UYSr21 Uo2(7)where:9Firestone, R.B., and Shirley, V.S., Table of Isotopes (Eighth Edition), JohnWiley and Sons, Inc., New York, 199
47、5.D 5811 003UIE= fractional uncertainty in the ingrowth efficiencyfactor,UVa= fractional uncertainty in the volume measurement,UYSr= fractional uncertainty in the chemical yield of thestrontium carrier,Uo= any additional fractional uncertainty that has beendetermined or estimated,and the other terms
48、 are as defined in 13.1 and 13.2.13.4 “A Priori” Minimum Detectable Radioactivity Con-centration (MDC):MDC Bq/L!54.65 =Cb1 2.71IE 3 ta3 Va3 YSr3 e2lSrt12t0!(8)where:Cb= number of counts accumulated during the counting ofthe sample aliquant due to instrument background,and the other terms are as defi
49、ned previously.NOTE 3The counting times of the sample aliquant and of instrumentbackground must be of equal length for Eq 6-8 to be valid. The valuesused for the terms in Eq 8 should be typical for the laboratory.14. Quality Control14.1 The project leader, as part of the external qualitycontrol program, shall submit blind quality control samples tothe analyst along with routine samples. These external qualitycontrol samples, which usually include duplicate and blanksamples, shall test sample collection and preparation
