1、Designation: D 4922 01Standard Test Method forDetermination of Radioactive Iron in Water1This standard is issued under the fixed designation D 4922; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A numbe
2、r 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 determination of55Fe in thepresence of59Fe by liquid scintillation counting. The a-prioriminimum detectable con
3、centration for this test method is 7.4E-3 Bq/mL.21.2 This test method was developed principally for thequantitative determination of55Fe. However, after proper cali-bration of the liquid scintillation counter with reference stan-dards of each nuclide,59Fe may also be quantified.1.3 This test method
4、was used successfully with Type IIIreagent water conforming to Specification D 1193.Itistheresponsibility of the user to ensure the validity of this testmethod for waters of untested matrices.1.4 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It
5、 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 a specifichazard statement, see Section 9.2. Referenced Documents2.1 ASTM Standards:D 1068 Test Methods for Iron in Wa
6、ter3D 1129 Terminology Relating to Water3D 1193 Specifications for Reagent Water3D 2777 Practice for Determination of Precision and Bias ofApplicable Methods of Committee D-19 on Water3D 3370 Practices for Sampling Water33. Terminology3.1 DefinitionsFor definitions of terms used in this testmethod,
7、refer to Terminology D 1129. For terms not defined inthis test method or in Terminology D 1129, refer to otherpublished glossaries.44. Summary of Test Method4.1 This test method describes the effective separation ofiron from the interfering cations of manganese, cobalt, zirco-nium, niobium, and cesi
8、um by anion exchange using acidwashes of various molarities. Subsequent elution of the iron isfollowed by phosphate precipitation to remove any residualzinc. The iron phosphate precipitate is dissolved in phosphoricacid and water and mixed with liquid scintillation cocktail. Thechemical yield is det
9、ermined by the recovery of iron carrierusing atomic absorption spectrophotometry or any proceduredescribed in Test Method D 1068.5. Significance and Use5.1 Radioactive iron is produced by neutron activation ofstable iron. Its concentration in reactor coolant is used tomonitor the corrosion of reacto
10、r parts such as reactor fuel-cladding material and reactor structural components.5.2 This technique effectively removes other activation andfission products such as isotopes of iodine, zinc, manganese,cobalt, and cesium by the addition of hold-back carriers and ananion exchange technique. The fissio
11、n products (zirconium-95and niobium-95) are selectively eluted with hydrochloric-hydrofluoric acid washes. The iron is finally separated fromZn+2by precipitation of FePO4at a pH of 3.0.6. Interferences6.1 Samples of reactor origin will also contain59Fe afterother radioactive contaminants have been r
12、emoved by anionexchange (see Fig. 1).59Fe is also an activation product whichdecays by b-g emission and will be a source of interference inthe quantitative determination of55Fe. The large difference inthe energies of their characteristic decay emissions makes itpossible to determine appropriate fact
13、ors to correct for the59Fespectral cross-talk in the55Fe region.6.2 Quenching, which may be caused by a number offactors, results in a reduction in the light output from thesample. The subsequent decrease in the spectral pulse heightwill cause variations in the counting efficiency with varyingdegree
14、s of quench. For this reason, it is necessary to monitorboth the changes in the55Fe efficiency and the59Fe cross-talkin the55Fe region as a function of quench. This techniquerecommends the use of the automatic external standard ratiosupplied by most liquid scintillation counters to monitor theamount
15、 of quench in a sample.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 Aug. 10, 2001. Published November 2001. Originallypublished as D 4922 89. Last previ
16、ous edition D 4922 94e1.2Currie, L., “Limits for Qualitative Detection and Quantitative Determination,”Analytical Chemistry, 40, 1968, pp. 586593.3Annual Book of ASTM Standards, Vol 11.01.4“American National Standard Glossary of Terms,” Nuclear Science andTechnology (ANSI N1.1), American National St
17、andards Institute, 1430 Broadway,New York, NY 10018.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.6.3 The final heating of the sample solution will drive off allexcess hydrochloric acid, ammonia, and water. These sub-stances are, t
18、herefore, effectively removed as possible quench-ing agents.6.4 Scintillation stock or sample solutions which have beenexposed to light must be dark adapted to avoid erratic resultsdue to light activation of the scintillator.NOTE 1It is the responsibility of the user to determine the requireddark ad
19、aptation period for the specific cocktail used.6.5 The stable iron content in a sample will interfere in thedetermination of the chemical recovery. Since the amount ofstable iron in a sample will depend on its sources, a correctionfor the iron in the sample must be made.7. Apparatus7.1 Liquid Scinti
20、llation Counter, with an automatic externalstandard and multiple energy region of interest (ROI) capabili-ties.7.2 Glass Scintillation Vials, 20-mLvials exhibiting suitableoptical reproducibility so as not to cause erratic results amongsamples.7.3 Atomic Absorption Spectrophotometer.7.4 Variable Spe
21、ed Peristaltic Pump, with controller. Pumpspeed should be between 5 and 8 mL/min.7.5 Centrifuge, using 100 mL centrifuge tubes.7.6 Volumetric Flasks.8. Reagents and Materials8.1 Purity of ReagentsReagent grade chemicals shall beused for all tests. Unless otherwise indicated, it is intended thatall r
22、eagents shall conform to the specifications of the Commit-tee on Analytical Reagents of the American Chemical Society,where such specifications are available.5Other grades may beused, provided it is first ascertained that the reagent is ofsufficiently high purity to permit its use without lessening
23、theaccuracy of the determination.8.2 Purity of WaterUnless otherwise indicated, referencesto water shall be understood to mean reagent water conformingto Specification D 1193, Type III.8.3 Anion Exchange Columns:8.3.1 ResinAGl-X8, 200-400 mesh; 25 mL previouslyequilibrated with 125 mL concentrated h
24、ydrochloric acid.8.3.2 ColumnsCommercially available plastic dryingtubes and ends (40 mL volume, 1.5 cm diameter, 15 cm long).68.3.3 TubingPump inlet tubing, approximately 18 in. inlength, and pump outlet tubing, approximately 30 in. in length.8.3.4 Polyethylene Porous Disc35 m pore size and 3.2mm t
25、hick.78.4 Scintillation CocktailCommercially prepared Insta-Gel scintillator or equivalent non-ionic detergent scintillator ofthe octyl-phenyl polyglycol ether type.8NOTE 2To obtain a clear aqueous final sample, the sample volumemust be kept below 1.8 mL with the addition of 15 mL Insta-Gel. It is t
26、heresponsibility of the user to determine the optimum sample volume tococktail volume to obtain a clear homogeneous solution for any otherliquid scintillation cocktail used.8.5 Ammonium Hydroxide (NH4OH)Concentrated (sp gr0.90).8.6 Ammonium Phosphate (0.5 M)Dissolve 66 g of am-monium monohydrogen ph
27、osphate (NH4)2HPO4 in 1000 mLof water.8.7 Cesium Carrier Solution (1 mg=1mL)Cesium ascesium chloride (CsCl) in dilute hydrochloric acid.98.8 Cobalt Carrier Solution (1 mg=1mL)Cobalt ascobalt chloride (CoCl2) in dilute hydrochloric acid.98.9 Hydrochloric Acid (sp gr 1.187)Concentrated HCl.8.10 Hydroc
28、hloric Acid 10 M (5 + 1)Dilute 833 mL ofconcentrated hydrochloric acid to 1000 mL with water in avolumetric flask.8.11 Hydrochloric Acid6M(1+1)Dilute 500 mL ofconcentrated hydrochloric acid to 1000 mL with water in avolumetric flask.8.12 Hydrochloric Acid 4 M (1 + 2)Dilute 333 mL ofconcentrated hydr
29、ochloric acid to 1000 mL with water in avolumetric flask.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 LaboratoryChemicals, BDH Lt
30、d., Poole, Dorset, U.K., and the United States Pharmacopeiaand National Formulary, U.S. Pharmaceutical Convention, Inc. (USPC), Rockville,MD.6Bio-Rad drying tubes, available from Bio-Rad, 2200 Wright Ave., Richmond,CA 94804, have been found satisfactory for this purpose.7Bel-Art porous polyethylene
31、sheets, in various pore sizes and thicknesses,available from BelArt, Pequannock, NJ 07440, have been found satisfactory for thispurpose.8Insta-Gel scintillator, available from United Technologies Packard, PackardInstrument Company, 2200 Warrensville Rd., Downers Grove, IL 60515 has beenfound to be s
32、uitable for this purpose.9Commercially available atomic absorption reference standards in 1 mg=1mLconcentrations may be used as carriers.FIG. 1 Percent of Total Radionuclide Activity Removed Per AcidWashD49220128.13 Hydrochloric Acid 0.5 M (1 + 23)Dilute 42 mL ofconcentrated hydrochloric acid to 100
33、0 mL with water in avolumetric flask.8.14 Hydrochloric Acid .01 M (1 + 1199)Dilute 20 mL of0.5 M HCl to 1000 mL with water in a volumetric flask.8.15 Hydrochloric(6 M)-Hydrofluoric Acid (0.5 M)Dilute 500 mL of concentrated hydrochloric acid (HCl) (sp gr1.187) and 20 mL of 49 % concentrated hydrofluo
34、ric acid (HF)to 1000 mL with water in a plastic or TFE-fluorocarbonvolumetric flask.8.16 Iron Carrier Solution (Fe+3as ferric chloride)9Dissolve 5.00 g of metallic iron in 300 mL of 6 M HCl, filter,dilute to 1 L, and calibrate using an atomic absorptionspectrophotometer (Test Methods D 1068).8.17 Ma
35、nganese Carrier Solution (1 mg=1mL)Mn+2indilute nitric acid (HNO3).98.18 Niobium Carrier Solution (1 mg=1mL)Nb+5in5 % hydrofluoric acid (1 + 9 M).98.19 Nitric Acid (sp gr 1.42)Concentrated (HNO3).8.20 Phosphoric Acid (sp gr 1.834)Concentrated(H3PO4).8.21 Sodium Hydroxide (6 M)Dissolve 24 g sodium hy
36、-droxide (NaOH) in 90 mL water, allow to cool, and dilute to100 mL with water and store in plastic bottles.8.22 Zinc Carrier Solution (1 mg=1mL)Zn+2in dilutehydrochloric acid.98.23 Zirconium Carrier Solution (1 mg=1mL)Zr+4indilute hydrochloric acid.99. Hazards9.1 HF is very hazardous and should be u
37、sed in a well-ventilated hood. Wear rubber gloves, safety glasses or goggles,and a laboratory coat.Avoid breathing any HF fumes. Clean allspills and wash thoroughly after using HF.Also, do not add HFto any glassware for it is a significant hazard and can affectanalytical accuracy.10. Sampling10.1 Co
38、llect samples in accordance with procedures pre-sented in Practices D 3370, as applicable.10.2 If the sample is not acidified at the time of collection,20 mLof concentrated HCl or HNO3should be added per 1000mL of sample.11. Calibration11.1 The reference standard for both iron isotopes willcontain 5
39、 mg iron carrier. Add 6 drops of concentratedphosphoric acid to the carrier solution and heat on a hot plateuntil it clears. This will drive off any excess hydrochloric acidand water (to less than 0.5 mL but do not allow to bake dry).Add 1 mL of water and swirl in the glass vial. This final carriers
40、olution should be colorless. Cool the vial to room temperature.Spike with the appropriate isotope and add 15 mL of scintil-lation cocktail. Cap and shake until the mixture is clear; thisstep ensures that the proper sample volume to scintillationcocktail volume ratio is obtained for a clear, homogene
41、oussolution. The volume of the reference standard should be suchthat its addition to the sample does not cause additionalquench.11.2 Prepare a series of quenched55Fe standards and aseries of quenched59Fe standards using various weights of ironcarrier or concentration or volumes, or both, of acid. Us
42、e theleast quenched standards in each set to optimize the liquidscintillation counter (LSC) discriminator settings and amplifiergain. Ensure that the55Fe spectrum does not spill over intothe59Fe ROI.11.3 Count each set of standards, with the LSC automaticexternal standard ratio selected on, to obtai
43、n approximately1 % counting statistics (approximately 10,000 counts) in theROI.11.4 Prepare a curve of the55Fe efficiency versus theexternal standard ratio.11.5 Prepare a crosstalk (XT) curve of the ratio of59Fecounts in the55Fe ROI to the59Fe counts in the59Fe ROIversus the external standard ratio.
44、12. Procedure12.1 Weigh an acidified and filtered aliquant of the sample(approximately 50 g) into a 100 mL centrifuge tube.12.2 Add 1 mL of the iron carrier solution and mix well.12.3 Add NaOH (6 M), mix, and heat to precipitate ironhydroxide.12.4 Centrifuge and decant the supernate to waste.12.5 Wa
45、sh the precipitate with 50 mL of hot water, centri-fuge and decant the supernate to waste.12.6 Dissolve the precipitate in 5 mL of 10 M HCl and add2 mL (2 mg) each of the appropriate hold-back carriers (Co+2,Zn+2,Zr+4,Nb+5,Mn+2, and Cs+1carriers). It is recommendedthat an aliquant of the sample be p
46、repared for gamma isotopicanalysis to verify the presence of potentially interfering nu-clides. Transfer the solution with 10 M HCl washes to a beakerand dilute to approximately 50 mL with 10 M HCl. Pass thesolution through an anion exchange column (AGl-X10 or1-X8, 200-400 mesh) previously equilibra
47、ted with 125 mL ofconcentrated HCl (sp gr 1.19). The column volume is approxi-mately 25 mL.The speed of the sample and washes through thecolumn should be between 5 and 8 mL/min.12.7 After the sample has been passed through the column,wash the column with 100 mL of 10 M HCl, then 150 mL of6 M HCl fol
48、lowed by 300 mL of 4 M HCl. If zirconium-95/niobium-95 activity is suspected, replace the 6 M HCl with the6 M HCl-0.5 M HF. Discard the effluents.NOTE 3If 6 M HCl-0.5 M HF is used, use only plastic ware. Columnplug should not be glass wool.12.8 Elute the iron with approximately 150 mL of 0.01 MHCl (
49、discard the first 20 mL) and collect the yellow bandindicative of Fe+3in a beaker. Do not allow the column to rundry.12.9 Add 10 mL of 0.5 M (NH4)2HPO4to the beaker andadd dropwise concentrated NH4OH until the pH is 3.0. The useof pH paper may not be sensitive enough to accuratelydetermine the pH. Gently heat the sample on a hot plate tocompletely precipitate the iron as Fe(PO4). Centrifuge, decant,and wash the precipitate with hot water.12.10 Dissolve the precipitate with a minimal amount of 6M HCl. Transfer the solution with approximately 10 mL wat
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