1、Designation: C1254 99 (Reapproved 2005) C1254 13Standard Test Method forDetermination of Uranium in Mineral Acids by X-RayFluorescence1This standard is issued under the fixed designation C1254; the number immediately following the designation indicates the year oforiginal adoption or, in the case of
2、 revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method covers the steps necessary for the preparation and analysis by X-ray fluoresce
3、nce (XRF) of mineral acidsolutions containing uranium.1.2 This test method is valid for those solutions containing 0.05 to 20 g uranium/L as presented to the spectrometer. Higherconcentrations may be covered by appropriate dilutions.1.3 This test method requires the use of an appropriate internal st
4、andard. Care must be taken to ascertain that samples analyzedby this test method do not contain the internal standard element or that this contamination has been corrected for mathematicallywhenever present. Such corrections are not addressed in this test method. Care must also be taken that the cho
5、ice of internalstandard and sample medium are compatible; that is, do not use yttrium with solutions containing HF or strontium with thosehaving H2SO4. Alternatively a scatter line may be used as internal standard.21.3 The values stated in SI units are to be regarded as the standard.1.4 This standar
6、d does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatorylimitations prior to use. Specific precautionary statement
7、s are given in Section 89 and Note 1.2. Referenced Documents2.1 ASTM Standards:2C859 Terminology Relating to Nuclear MaterialsC982 Guide for Selecting Components for Energy-Dispersive X-Ray Fluorescence (XRF) Systems (Withdrawn 2008)3C1118 Guide for Selecting Components for Wavelength-Dispersive X-R
8、ay Fluorescence (XRF) Systems (Withdrawn 2011)3D1193 Specification for Reagent WaterE135 Terminology Relating to Analytical Chemistry for Metals, Ores, and Related Materials2.2 Other Document:NBS Handbook 111,ANSI/HPS N43.22001 Radiation Safety for X-RayX-ray Diffraction and X-Ray Fluorescence Analy
9、sisEquipment43. Terminology3.1 Definitions:3.1.1 See TerminologyTerminologies E135 and C859 for definitions of terms applicable to this test method.4. Summary of Test Method4.1 Solution standards containing 0.025 g/L uraniumg uranium/L to 20 g/L uraniumg uranium/L and an appropriate internalstandard
10、 (usually either yttrium or strontium) strontium), unless a scatter line is used in lieu of, are placed in a liquid sample holderof an X-ray spectrometer and exposed to an X-ray beam capable of exciting the uranium L-alpha emission line and the appropriate1 This test method is under the jurisdiction
11、 of ASTM Committee C26 on Nuclear Fuel Cycle and is the direct responsibility of Subcommittee C26.05 on Methods of Test.Current edition approved June 1, 2005Jan. 1, 2013. Published December 2005January 2013. Originally approved in 1993. Last previous edition approved in 1999 asC1254 99.C1254 99 (200
12、5). DOI: 10.1520/C1254-99R05.10.1520/C1254-13.2 For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.3 The last a
13、pproved version of this historical standard is referenced on www.astm.org.4 Available as a photocopy from the U.S. Department of Commerce, National Institute of Standards and Technology, Gaithersburg, MD 20899.from the Health PhysicsSociety, McLean, Virginia, 22101.This document is not an ASTM stand
14、ard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases
15、 only the current versionof the standard as published by ASTM is to be considered the official document.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1emission line for the internal standard (usually the K-alpha line). The intensitie
16、s generated are measured by an appropriate detector.The intensity ratio values obtained from this data are used to calibrate the X-ray analyzer.5. Significance and Use5.1 This test method is applicable to aqueous solutions of uranium containing 0.05 to 20 g uranium per litre of solutionpresented to
17、the spectrometer.5.2 Either wavelength-dispersive or energy-dispersive X-ray fluorescence systems may be used provided the softwareaccompanying the system is able to accommodate the use of internal standards.6. Interferences6.1 This test method requires the use of an appropriate internal standard. C
18、are must be taken to ascertain that samples analyzedby this test method do not contain the internal standard element or that this contamination has been corrected for mathematicallywhenever present. Such corrections are not addressed in this test method.6.2 Alternatively a scatter line may be used a
19、s internal standard in which case the preparation of internal standard solutions andsubsequent doping of samples and calibration standards is unnecessary.56.3 Sample must not contain significant concentration of any elements that have mass absorption edges that fall between theenergies of the uraniu
20、m L-alpha line and the internal standard line.6.4 Care must also be taken that the choice of internal standard and sample medium are compatible; that is, do not use yttriumwith solutions containing HF or strontium with those having H2SO4.7. Apparatus7.1 X-Ray SpectrometerSee Guide C982 or Guide C111
21、8 for the selection of the X-ray spectrometer. This test method is validfor either energy-dispersive or wavelength-dispersive systems.7.2 Sample Cups:7.2.1 Prepare liquid sample cups for the X-ray spectrometer as described by the manufacturer. Vented, disposable sample cupswith snap-on caps are sati
22、sfactory for most such analyses; such cups decrease the likelihood of contamination between samples.7.2.2 Polyester, polyethylene, and polypropylene films have been used successfully as the film window for such cups. Testsshould be performed to determine the serviceability of any film chosen before
23、insertion into the instrument.7.3 Solution DispenserThe dispenser for the internal standard solution should be capable of reproducibly dispensing theinternal standard to a level of 0.5 % relative standard deviation of the volume dispensed.8. Reagents and Materials8.1 Purity of ReagentsReagent grade
24、chemicals shall be used in all tests. Unless otherwise indicated, it is intended that allreagents conform to the specifications of the Committee of Analytical Reagents of the American Chemical Society where suchspecifications are available.6 Other grades may be used provided it is first ascertained
25、that the reagent is of sufficiently high purityto permit its use without lessening the accuracy of the determination.8.2 Purity of WaterUnless otherwise indicated, references to water shall mean reagent water conforming to SpecificationD1193.8.3 Ferric Nitrate, Fe(NO3)39H2O.8.4 Nitric Acid, HNO3, co
26、ncentrated (70 %).8.5 Strontium Carbonate, SrCO3.8.6 Uranium Oxide, U3O8, NBL CRM-1297 (or equivalent).8.7 Yttrium Oxide, Y2O3.9. Technical Precautions9.1 XRF equipment analyzes by the interaction of ionizing radiation with the sample. Applicable safety regulations and standardoperating procedures m
27、ust be reviewed prior to the use of such equipment. All modern XRF spectrometers are equipped with safety5 Andermann, George, and Kemp, J. W., “Scattered X-Rays as Internal Standards in X-Ray Spectroscopy,” Analytical Chemistry, Vol. 20(8), 1958.6 Reagent Chemicals, American Chemical Society Specifi
28、cations, American Chemical Society, Washington, DC. For suggestions on the testing of reagents not listed bythe American Chemical Society, see Analar Standards for Laboratory Chemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeia and NationalFormulary, U.S. Pharmacopeial Conven
29、tion, Inc. (USPC), Rockville, MD.7 Available from the U.S. Department of Energy, New Brunswick Laboratory, D350, 9800 South Cass Avenue, Argonne, IL 60439, Attn: Reference Material Sales.C1254 132interlocks to prevent accidental penetration of the X-ray beam by the user. Do NOT override these interl
30、ocks without propertraining, or a second knowledgeable person present during such operation. (See NBS Handbook 111.)ANSI/HPS N43.22001.)9.2 Instrument performance may be influenced by environmental factors such as heat, vibration, humidity, dust, stray electronicnoise, and line voltage stability. Th
31、ese factors and performance characteristics should be reviewed prior to use of this standard.10. Preparation of Apparatus10.1 Chamber EnvironmentThe standards and samples used in this test method are corrosive liquids. Some fumes will beemitted from the sample cups. These fumes may be detrimental to
32、 the spectrometer chamber. It is desirable to flush this chamberwith an inert gas (usually helium) appropriate gas (for example, helium and nitrogen) before and during analysis. Some X-rayspectrometers control the change of sample chamber atmosphere (air, vacuum, helium) helium, nitrogen) automatica
33、lly through thesoftware; in others, it must be done manually. Follow the instrument manufacturers recommendations to achieve the inert gasenvironment.NOTE 1Caution: Allow sufficient stabilization time before analysis. Care must be taken to ensure that a vacuum environment is not chosen with liquidsa
34、mples.10.2 X-Ray Power SupplyIf the power to the X-ray tube is not controlled 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 instrument andchoice of X-ray tube. Allow sufficient stabilizati
35、on time prior to analysis.11. Calibration and Standardization11.1 Internal Standard Solution (25.0 g/L):11.1.1 Weigh 25 g of the chosen internal standard compound into an 800-mL beaker. Cover with water. Add concentrated nitricacid slowly. For yttrium oxide the reaction will be slow and may require
36、heating. For strontium carbonate, the reaction will bevigorous.11.1.2 Heat on a hot plate if necessary to complete the dissolution.11.1.3 Cool the solution to room temperature, and transfer to a 1000-mL volumetric flask. (Filter the solution if necessary.)Dilute to volume with water and mix thorough
37、ly.11.2 Impurity Stock Solution (Optional):11.2.1 Weigh 50 g of reagent grade ferric nitrate, Fe(NO3)39H2O, into a 600-mL beaker.11.2.2 Dissolve the crystals in 200 mL of water and 50 mL of concentrated nitric acid.11.2.3 When cool, transfer the solution to a 1000-mL volumetric flask and dilute to v
38、olume with water.11.3 Uranium Calibration Standards:11.3.1 Prepare a uranium standard for each concentration level by weighing into a 150-mL beaker the amounts of uranium oxidegiven in Table 1.TABLE 1 Uranium Calibration StandardsConcentration,(g/L)Weight U3O8(CRM-129)AInternalStandard,(mL)Impurity
39、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 1.415
40、56 4 10014.00 1.65148 4 10 10016.00 1.88741 4 10018.00 2.12333 4 10 10020.00 2.35926 4 100A Weights will need to be adjusted for the purity of the uranium reference materialused. See the certification accompanying the material. Weights indicated are forNBL CRM-129 (no longer available; use NBL CRM-1
41、29 or equivalent). Use of theimpurity solution is optional.C1254 13311.3.2 Dissolve the oxide in 25 mL of water and 25 mL concentrated nitric acid. Heat on a hot plate, if necessary to completethe dissolution.11.3.3 When cool, transfer each solution to a properly labeled 100-mL volumetric flask. Add
42、 the amount of internal standardsolution and impurity solution (if desired) indicated in Table 1 to each volumetric flask.NOTE 2The internal standard solution may be added using a dispensing pipet if desired. However, care must be taken to ensure that no adjustmentto the dispenser is made between us
43、e for standards and use for samples.11.3.4 Dilute to volume with water and mix thoroughly.11.4 Instrument Calibration:11.4.1 Follow manufacturers instructions for the instrument in use to obtain intensity data for the uranium L-alpha and theinternal standard line or scatter line for each standard.11
44、.4.2 Exercise care that the analytical conditions determined appropriate for the instrument in use are documented, or recorded,in sufficient detail that these may be reproduced in subsequent runs and when analyzing the samples.11.4.3 Calculate the uranium/internal standard ratios from the data obtai
45、ned in 10.4.111.4.1. Calculate a calibration curve usingthese ratios. The curve should be at least a second order polynomial (quadratic) or should have a term to correct for uraniumself-absorption. A third-order equation may be used if the software allows. All have been found acceptable. Currently a
46、vailableinstrument software would contain one or the other or perhaps both. (A should need curve equation. A complete discussion of themathematical derivation of the followingavailable equations is outside the scope of this procedure. Explanations of correctionmodels and interelement effects are fou
47、nd in several sources.8,9) The quadratic equation will have the form:Y 5DX 31CX 21BX1A (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 5MX1B! 11aX/100!
48、 (2)where:Y = concentration of uranium,X = uranium/internal standard 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 as appropriate for the software used.12. Procedure12.1 Sample Prep
49、aration:12.1.1 Shake the sample and pipet an appropriate aliquot into a tared 50-mL volumetric flask.NOTE 3Some estimate of the approximate g U/L will be necessary to determine the appropriate dilution. This may be obtained by gamma countingof the incoming sample, prior knowledge of the origin of the sample or some other scheme devised by the user. Such schemes are outside the scope ofthis standard.12.1.2 Obtain the gross weight of the sample and flask. (If an answer on a weight basis is not desired, this may be omitted.)12.1.3 Add 2 mL of the internal standa
