1、Designation: C 1254 99 (Reapproved 2005)Standard Test Method forDetermination of Uranium in Mineral Acids by X-RayFluorescence1This standard is issued under the fixed designation C 1254; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revisi
2、on, the year of 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 steps necessary for thepreparation and analysis by X-ray fluorescence (XR
3、F) ofmineral acid solutions containing uranium.1.2 This test method is valid for those solutions containing0.05 to 20 g uranium/L as presented to the spectrometer.Higher concentrations may be covered by appropriate dilu-tions.1.3 This test method requires the use of an appropriateinternal standard.
4、Care must be taken to ascertain that samplesanalyzed by this test method do not contain the internalstandard element or that this contamination has been correctedfor mathematically whenever present. Such corrections are notaddressed in this test method. Care must also be taken that thechoice of inte
5、rnal standard and sample medium are compatible;that is, do not use yttrium with solutions containing HF orstrontium with those having H2SO4. Alternatively a scatter linemay be used as internal standard.21.4 The values stated in SI units are to be regarded as thestandard.1.5 This standard does not pu
6、rport 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 use. Specific precau-tionary statements are give
7、n in Section 8 and Note 1.2. Referenced Documents2.1 ASTM Standards:3C 982 Guide for Selecting Components for Energy Disper-sive X-Ray Fluorescence (XRF) SystemsC 1118 Guide for Selecting Components for Wavelength-Dispersive X-Ray Fluorescence (XRF) SystemsD 1193 Specification for Reagent WaterE 135
8、 Terminology Relating to Analytical Chemistry forMetals, Ores, and Related Materials2.2 Other Document:NBS Handbook 111, Radiation Safety for X-Ray Diffractionand X-Ray Fluorescence Analysis Equipment43. Terminology3.1 Definitions:3.1.1 See Terminology E 135 for definitions of terms appli-cable to t
9、his test method.4. Summary of Test Method4.1 Solution standards containing 0.025 g/L uranium to 20g/L uranium and an appropriate internal standard (usuallyeither yttrium or strontium) are placed in a liquid sample holderof an X-ray spectrometer and exposed to an X-ray beamcapable of exciting the ura
10、nium L-alpha emission line and theappropriate emission line for the internal standard (usually theK-alpha line). The intensities generated are measured by anappropriate detector. The intensity ratio values obtained fromthis data are used to calibrate the X-ray analyzer.5. Significance and Use5.1 Thi
11、s test method is applicable to aqueous solutions ofuranium containing 0.05 to 20 g uranium per litre of solutionpresented to the spectrometer.5.2 Either wavelength-dispersive or energy-dispersiveX-ray fluorescence systems may be used provided the softwareaccompanying the system is able to accommodat
12、e the use ofinternal standards.6. Apparatus6.1 X-Ray SpectrometerSee Guide C 982 or GuideC 1118 for the selection of the X-ray spectrometer. This testmethod is valid for either energy-dispersive or wavelength-dispersive systems.1This test method is under the jurisdiction of ASTM Committee C26 on Nuc
13、learFuel Cycle and is the direct responsibility of Subcommittee C26.05 on Methods ofTests.Current edition approved June 1, 2005. Published December 2005. Originallyapproved in 1993. Last previous edition approved in 1999 as C 125499.2Andermann, George, and Kemp, J. W., “Scattered X-Rays as Internal
14、Standardsin X-ray Spectroscopy,” Analytical Chemistry, Vol 20(8), 1958.3For 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 Document Summary page onthe AST
15、M website.4Available as a photocopy from the U.S. Department of Commerce, NationalInstitute of Standards and Technology, Gaithersburg, MD 20899.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.6.2 Sample Cups:6.2.1 Prepare liquid samp
16、le cups for the X-ray spectrometeras described by the manufacturer. Vented, disposable samplecups with snap-on caps are satisfactory for most such analyses;such cups decrease the likelihood of contamination betweensamples.6.2.2 Polyester, polyethylene, and polypropylene films havebeen used successfu
17、lly as the film window for such cups. Testsshould be performed to determine the serviceability of any filmchosen before insertion into the instrument.6.3 Solution DispenserThe dispenser for the internal stan-dard solution should be capable of reproducibly dispensing theinternal standard to a level o
18、f 0.5 % relative standard deviationof the volume dispensed.7. Reagents and Materials7.1 Purity of ReagentsReagent grade chemicals shall beused in all tests. Unless otherwise indicated, it is intended thatall reagents conform to the specifications of the Committee ofAnalytical Reagents of the America
19、n Chemical Society wheresuch specifications are available.5Other grades may be usedprovided it is first ascertained that the reagent is of sufficientlyhigh purity to permit its use without lessening the accuracy ofthe determination.7.2 Purity of WaterUnless otherwise indicated, referencesto water sh
20、all mean reagent water conforming to SpecificationD 1193.7.3 Ferric Nitrate, Fe(NO3)39H2O.7.4 Nitric Acid, HNO3, concentrated (70 %).7.5 Strontium Carbonate, SrCO3.7.6 Uranium Oxide,U3O8, NBL CRM-1296(or equivalent).7.7 Yttrium Oxide,Y2O3.8. Technical Precautions8.1 XRF equipment analyzes by the int
21、eraction of ionizingradiation with the sample. Applicable safety regulations andstandard operating procedures must be reviewed prior to theuse of such equipment. All modern XRF spectrometers areequipped with safety interlocks to prevent accidental penetra-tion of the X-ray beam by the user. Do NOT o
22、verride theseinterlocks without proper training, or a second knowledgeableperson present during such operation. (See NBS Handbook111.)8.2 Instrument performance may be influenced by environ-mental factors such as heat, vibration, humidity, dust, strayelectronic noise, and line voltage stability. The
23、se factors andperformance characteristics should be reviewed prior to use ofthis standard.9. Preparation of Apparatus9.1 Chamber EnvironmentThe standards and samplesused in this test method are corrosive liquids. Some fumes willbe emitted from the sample cups. These fumes may bedetrimental to the sp
24、ectrometer chamber. It is desirable to flushthis chamber with an inert gas (usually helium) before andduring analysis. Some X-ray spectrometers control the changeof sample chamber atmosphere (air, vacuum, helium) auto-matically through the software; in others, it must be donemanually. Follow the ins
25、trument manufacturers recommenda-tions to achieve the inert gas environment.NOTE 1Caution: Allow sufficient stabilization time before analysis.Care must be taken to ensure that a vacuum environment is not chosenwith liquid samples.9.2 X-Ray Power SupplyIf the power to the X-ray tube isnot controlled
26、 by the instrument software, set the propercombination of voltage and current for the instrument in use.These settings must be determined by the user for his instru-ment and choice of X-ray tube. Allow sufficient stabilizationtime prior to analysis.10. Calibration and Standardization10.1 Internal St
27、andard Solution (25.0 g/L):10.1.1 Weigh 25 g of the chosen internal standard com-pound into an 800-mL beaker. Cover with water. Add concen-trated nitric acid slowly. For yttrium oxide the reaction will beslow and may require heating. For strontium carbonate, thereaction will be vigorous.10.1.2 Heat
28、on a hot plate if necessary to complete thedissolution.10.1.3 Cool the solution to room temperature, and transferto a 1000-mL volumetric flask. (Filter the solution if neces-sary.) Dilute to volume with water and mix thoroughly.10.2 Impurity Stock Solution (Optional):10.2.1 Weigh 50 g of reagent gra
29、de ferric nitrate,Fe(NO3)39H2O, into a 600-mL beaker.10.2.2 Dissolve the crystals in 200 mL of water and 50 mLof concentrated nitric acid.10.2.3 When cool, transfer the solution to a 1000-mLvolumetric flask and dilute to volume with water.10.3 Uranium Calibration Standards:10.3.1 Prepare a uranium s
30、tandard for each concentrationlevel by weighing into a 150-mL beaker the amounts ofuranium oxide given in Table 1.10.3.2 Dissolve the oxide in 25 mL of water and 25 mLconcentrated nitric acid. Heat on a hot plate, if necessary tocomplete the dissolution.10.3.3 When cool, transfer each solution to a
31、properlylabeled 100-mL volumetric flask. Add the amount of internalstandard solution and impurity solution (if desired) indicated inTable 1 to each volumetric flask.NOTE 2The internal standard solution may be added using a dispens-ing pipet if desired. However, care must be taken to ensure that noad
32、justment to the dispenser is made between use for standards and use forsamples.10.3.4 Dilute to volume with water and mix thoroughly.10.4 Instrument Calibration:5Reagent Chemicals, American Chemical Society Specifications, AmericanChemical Society, Washington, DC. For suggestions on the testing of r
33、eagents notlisted by the American Chemical Society, see Analar Standards for LaboratoryChemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeiaand National Formulary, U.S. Pharmaceutical Convention, Inc. (USPC), Rockville,MD.6Available from the U.S. Department of Energy, New Brun
34、swick Laboratory,D350, 9800 South CassAvenue,Argonne, IL 60439,Attn: Reference Material Sales.C 1254 99 (2005)210.4.1 Follow manufacturers instructions for the instru-ment in use to obtain intensity data for the uranium L-alpha andthe internal standard line for each standard.10.4.2 Exercise care tha
35、t the analytical conditions deter-mined appropriate for the instrument in use are documented, orrecorded, in sufficient detail that these may be reproduced insubsequent runs and when analyzing the samples.10.4.3 Calculate the uranium/internal standard ratios fromthe data obtained in 10.4.1. Calculat
36、e a calibration curve usingthese ratios. The curve should be at least a second orderpolynomial (quadratic) or should have a term to correct foruranium self-absorption. A third-order equation may be used ifthe software allows. All have been found acceptable. Currentlyavailable instrument software wou
37、ld contain one or the other orperhaps both. (A complete discussion of the mathematicalderivation of the following equations is outside the scope ofthis procedure. Explanations of correction models and inter-element effects are found in several sources.7,8) The quadraticequation will have the form:Y
38、5 DX31 CX21 BX 1 A (1)where:Y = concentration of uranium,X = uranium/internal standard intensity ratio, andA, B, C, D = coefficients of quadratic equation.10.4.4 For self-absorption the equation will have the form:Y 5 MX 1 B! 1 1 aX/100! (2)where:Y = concentration of uranium,X = uranium/internal sta
39、ndard intensity ratio,M = slope of straight line,B = intercept of straight line, anda = self-absorption coefficient.NOTE 3Units used for Y in Eq 1 and Eq 2 may be changed asappropriate for the software used.11. Procedure11.1 Sample Preparation:11.1.1 Shake the sample and pipet an appropriate aliquot
40、into a tared 50-mL volumetric flask.NOTE 4Some estimate of the approximate g U/L will be necessary todetermine the appropriate dilution. This may be obtained by gammacounting of the incoming sample, prior knowledge of the origin of thesample or some other scheme devised by the user. Such schemes are
41、outside the scope of this standard.11.1.2 Obtain the gross weight of the sample and flask. (Ifan answer on a weight basis is not desired, this may beomitted.)11.1.3 Add 2 mL of the internal standard solution; dilute tovolume with water and mix thoroughly.11.2 Counting the Sample:11.2.1 Set the X-ray
42、 spectrometer to the conditions noted in10.4.1. If the analytical conditions are controlled by computer,start the computer according to manufacturers instructions forthe software in use.11.2.2 Shake each flask to mix thoroughly. Fill the liquidsample cup with the recommended amount of liquid for the
43、instrument in use.11.2.3 Following manufacturers instrumental instructions,obtain intensities for the uranium L-alpha line and the internalstandard line.11.2.4 Calculate the uranium concentration in the flaskusing the appropriate equation.NOTE 5Additional factors, such as volume, weight, isotopic co
44、rrec-tion, secondary dilutions, may be included with the listed equations toobtain results on the proper basis for the users application.12. Precision and Bias12.1 There is no readily available certified material (ura-nium dissolved in mineral acid) for this test method. However,two solutions of NBL
45、 CRM-1149(U3O8) were prepared.12.1.1 The first solution, with a theoretical value of 0.03916g uranium per g solution (g U/g solution), corresponding to;42.4 g U/L, was prepared by dissolving ;50 g (weighed tothe nearest 0.1 mg) as outlined in 10.3.4 and transferring to atared 1000mL volumetric flask
46、. This solution was diluted tovolume with water, mixed thorughly and weighed. Aliquots ofthis solution were prepared by five different technicians andanalyzed on two different X-ray spectrometers over a four-month period. The average of 30 determinations (see Table2for data) was 0.03923 g U/g soluti
47、on, a relative difference of0.27 % from the theoretical value, with a relative standarddeviation of 0.53 %12.1.2 The second solution, with a theoretical value of0.000984 g uranium per gram solution, corresponding to ;0.17Bertin, Eugene P., Introduction to X-Ray Spectrometric Analysis, Plenum Press,N
48、ew York and London, 1978.8Tertian, R., and Claisse, F., Principles of Quantitative X-Ray FluorescenceAnalysis, Heyden and Son, London, Philadelphia, and Rheine, 1982.9No longer available; see Table 1, Footnote A.TABLE 1 Uranium Calibration StandardsConcentration,(g/L)WeightU3O8(CRM-129)AInternalStan
49、dard,(mL)Impurity Solution,(mL)AFinal Volume,(mL)0.025 0.00295 4 5 1000.050 0.00590 4 1000.100 0.01180 4 5 1000.500 0.05898 4 1001.000 0.11796 4 5 1001.250 0.14745 4 1001.500 0.17694 4 5 1001.750 0.20644 4 1002.00 0.23593 4 5 1004.00 0.47185 4 1006.00 0.70778 4 5 1008.00 0.94370 4 10010.00 1.17963 4 10 10012.00 1.41556 4 10014.00 1.65148 4 10 10016.00 1.88741 4 10018.00 2.12333 4 10 10020.00 2.35926 4 100AWeights will need to be adjusted for the purity of the uranium referencematerial used. See the certification accompanying the material. Weights indicatedare for
