1、Designation: D5174 07 (Reapproved 2013)Standard Test Method forTrace Uranium in Water by Pulsed-Laser Phosphorimetry1This standard is issued under the fixed designation D5174; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the yea
2、r 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 determination of totaluranium, by concentration, in water within the calibrated range
3、of the instrument, 0.1 g/Lor greater. Samples with uranium bymass, levels above the laser phosphorimeter dynamic range arediluted to bring the concentration to a measurable level.1.2 This test method was used successfully with reagentwater. It is the users responsibility to ensure the validity of th
4、istest method for waters of untested matrices.1.3 The values stated in SI units are to be regarded as thestandard.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 s
5、afety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D1129 Terminology Relating to WaterD1193 Specification for Reagent WaterD2777 Practice for Determination of Precision and Bias ofApplicable Test Methods of Co
6、mmittee D19 on WaterD3370 Practices for Sampling Water from Closed ConduitsD3856 Guide for Management Systems in LaboratoriesEngaged in Analysis of WaterD4448 Guide for Sampling Ground-Water Monitoring WellsD5847 Practice for Writing Quality Control Specificationsfor Standard Test Methods for Water
7、AnalysisD6001 Guide for Direct-Push Groundwater Sampling forEnvironmental Site CharacterizationE131 Terminology Relating to Molecular Spectroscopy3. Terminology3.1 Definitions:3.1.1 For definitions of terms used in this test method, referto Terminologies D1129 and E131.3.1.2 For terms not defined in
8、 this test method or inTerminology D1129 or E131, reference may be made to otherpublished glossaries.34. Summary of Test Method4.1 This test method is based on the utilization of a laserphosphorimeter to determine total uranium, by mass, in watersamples.4.2 Asample aliquant is pipetted into a pretre
9、ated glass vial.Concentrated HNO3and hydrogen peroxide are added and thesample heated to dryness. This step is repeated as necessaryand the residue is dissolved in dilute HNO3. A complexant isadded to an aliquant of this sample and analyzed in thephosphorimeter.4.3 For screening purposes only, an al
10、iquant of the samplemay be pipetted directly into the phosphorimeter cell contain-ing uranium complexant and read. This cannot be done if thesample was preserved with HCl or if the matrix is not known.5. Significance and Use5.1 This test method is useful for the analysis of totaluranium in water fol
11、lowing wet-ashing, as required, due toimpurities or suspended materials in the water.6. Interferences6.1 Absorption (Inner Filter Effect)This effect is moresevere with ultraviolet excitation light (337 nm) than withvisible excitation because many prevalent compounds havepi-bonding and absorb strongl
12、y in this region. Ferric iron andoxy-anions such as nitrate and organic acids are examples.Visible excitation (425 nm) may be absorbed by yellowsolutions, for example, chromate. The consequences of thismay be reduced signals and low analysis results.6.2 LumiphorsMany organic substances, such as humi
13、cacids and organic degradation products from incomplete ashing1This 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 Jan. 1, 2013. Published January 2013. Origina
14、llyapproved in 1991. Last previous edition approved in 2007 as D5174 07. DOI:10.1520/D5174-07R13.2For 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 standards Docum
15、ent Summary page onthe ASTM website.3See American National Standard Glossary of Terms in Nuclear Science andTechnology (ANSI N1.1), available from American National Standards Institute,1430 Broadway, New York, NY 10014, www.ansi.org.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, W
16、est Conshohocken, PA 19428-2959. United States1emit luminescence of varying lifetimes after excitation. Anadvantage of kinetic phosphorescence measurement is theability to determine if interferences are present by observingthe lifetime of the decay.6.3 QuenchingShortened triplet-state lifetime and r
17、educedphosphorescence intensities of the excited uranyl complexresult when quenching occurs. Reliable results cannot beobtained when quenching exceeds 80 to 90 %. Reducing agentssuch as alcohols, halides except fluoride, and metals withelectronic energy levels overlapping those of uranyl ion arestro
18、ng quenching agents; examples are silver, lead, iron (II),manganese (II), and thallium. Results from single time-gatedinstruments are particularly sensitive to even mild quenchingagents such as aluminum (III), magnesium (II), calcium (II),and strontium (II).6.4 Competing ReactionsFor this test metho
19、d to performwell, the uranyl ion must be protected from various intermo-lecular mechanisms which rapidly quench the uranyl lumines-cence. Complexation fulfills this need and examples of effec-tive agents are phosphoric acid, polyphosphates, and Uraplex.46.5 Hydrochloric acid, if present, is an inter
20、ference unlesseliminated during digestion.6.6 If the concentration of uranium in the samples exceedsthe calibrated range of the instrument, samples are diluted1/100 (or otherwise as appropriate) in 0.8 M nitric acid.6.7 When concentrations of interferences in the samplesprevent obtaining an acceptab
21、le measurement, samples arediluted in 0.8 M nitric acid to minimize the effects of theinterferences.7. Apparatus7.1 Laser Phosphorimeter,4meeting the following criteria:7.1.1 Detection LimitThe MDL for uranium is generally0.1 g/L or less.7.1.2 Dynamic RangeThe phosphorimeter must handle ananalytical
22、 range of 400 or greater.7.1.3 Instrumental PrecisionThe precision of repetitivemeasurements sufficient to obtain a relative standard deviationof less than 15 % at the low points of the calibration curves.7.2 LabwareIf samples containing less than 0.1 g/Luranium are to be analyzed, digestion vessels
23、 (both TFE-fluorocarbon and glassware) if used, and liquid scintillationvials should be leached in 4 M nitric acid and rinsed thoroughlywith deionized water before using. This is necessary to reducesample contamination from leachable uranium.8. Reagents8.1 Purity of ReagentsReagent grade chemicals s
24、hall beused in all tests. Unless otherwise indicated, it is intended thatall reagents shall conform to the specifications of the Commit-tee onAnalytical Reagents of theAmerican Chemical Society.5Other grades may be used, provided it is first ascertained thatthe reagent is of sufficiently high purity
25、 to permit its usewithout lessening the accuracy of the determination. Reagentblanks shall be run with all determinations.8.2 Purity of WaterUnless otherwise indicated, referencesto water shall be understood to mean reagent water conformingto Specification D1193, Type I or better.8.3 Hydrogen Peroxi
26、deStandard 30 % solution of hydro-gen peroxide (H2O2); commercially available reagent grade.8.4 Nitric Acid(sp gr 1.42) concentrated nitric acid(HNO3).8.5 Nitric Acid 4 MAdd 250 mL of concentrated nitricacid (HNO3) to 500 mL of reagent water and dilute to 1L inreagent water, Type 1 or better.8.6 Nit
27、ric Acid 0.8 MAdd 50 mL of concentrated nitricacid (HNO3) to 500 mL of reagent water and dilute to 1L inreagent water, Type 1 or better.NOTE 1Reagent blank shall be run on the nitric acid to analyze for thelevel of uranium.8.7 Uranium ComplexantPhosphoric acid or Uraplex4aresome complexants that may
28、 be used.9. Calibration and Standardization9.1 Preparation of Standards and Sample for LaserMeasurementStandards and samples shall be prepared in asimilar matrix for phosphorimetric measurement. The finalsample preparation step puts uranium into a 0.8 M HNO3matrix. Use uranium standards traceable to
29、 a National Stan-dardizing Laboratory such as NIST or NPL.9.2 Calibration of Phosphorimeter The instructions forthe operation of the laser phosphorimeter are provided by themanufacturer. The phosphorimeter should be calibrated eachday of use and the calibration verified with standards obtainedfrom a
30、 different stock solution than used to prepare thecalibration standards.10. Sampling10.1 Collect the sample in accordance with the applicablemethods as described in Practices D3370, D4448, and GuideD6001 or other approved practices or guides.11. Procedure11.1 Pipet 5.0 mL of sample into a glass vial
31、 previouslytreated as described in 7.2.11.2 Add 1 mL of concentrated HNO3and two or threedrops of 30 % hydrogen peroxide.4The sole source of supply of the apparatus known to the committee at this timeis Chemchek Instruments, Inc., 1845 Terminal Drive, Suite #101, Richland, WA,99354-4959. Consult app
32、ropriate equipment manuals for explanations of calibrationand calculations. If you are aware of alternative suppliers, please provide thisinformation to ASTM International Headquarters. Your comments will receivecareful consideration at a meeting of the responsible technical committee,1whichyou may
33、attend.5Reagent Chemicals, American Chemical Society Specifications, AmericanChemical Society, Washington, DC. For Suggestions on the testing of reagents notlisted by the American Chemical Society, see Annual Standards for LaboratoryChemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pha
34、rmacopeiaand National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville,MD.D5174 07 (2013)211.3 Place the vial on a hot plate and heat to dryness. Takecare that spattering of the sample does not occur.NOTE 2Placing the vial in a 50-mL beaker makes it easier to handleand not so apt to
35、be knocked over.11.4 Remove the vials from the hot plate and add 1 mL ofconcentrated HNO3, two or three drops of 30 % hydrogenperoxide, and heat to dryness. Repeat as necessary until only awhite or translucent residue remains.11.5 Add 1.0 mL of 4 M HNO3and warm gently, ifnecessary, to dissolve the r
36、esidue. Then add 4.0 mL of waterconforming to Specification D1193, Type I or better . Swirl tomix thoroughly.11.6 Analyze the solution according to the instructionmanual provided with the phosphorimeter.NOTE 3If the concentration of uranium in the prepared sample fallsabove the calibrated range of t
37、he instrument, dilutions should be madeusing 0.8 M HNO3, used for the final sample preparation.NOTE 4Lifetime values below 200 us indicate significant quenchingin the sample and could affect the quality of results obtained. The problemcan often be addressed by diluting samples in 0.8 M HNO3.12. Calc
38、ulation12.1 Refer to the instrument manual for explanation ofcalculations.12.2 Estimate the uncertainty of analysis by preparing andanalyzing replicate analyses at different known concentrationsand calculating the bias and standard deviation as a function ofconcentration.12.3 Estimate the method det
39、ection limit (MDL) andmethod reporting limit (RL) on a periodic basis or followingmajor maintenance of the instrument by processing seven ormore replicate reagent blanks through the entire above methodabove. Calculate the standard deviation SBand the MDL asdescribed in Eq 1 and Eq 2 below.NOTE 5Soft
40、ware supplied with certain KPAinstruments excludes datain time gates where net signal intensity falls to zero or below. Further, thesoftware censors final concentration results (that is, reports as “less than”values) when there is insufficient net intensity data to perform a best-fitregression to th
41、e decay plot. As a result, during the analysis of blanks theinstrument will often yield non-numerical concentration results (that is,“less-than” values). In such cases, “positive” results may be induced byspiking the MDL study “blank” samples at a concentration approximately25 times the estimated/ca
42、lculated MDL. MDL target concentrationsshould be adjusted and study measurements be repeated iteratively until asatisfactory concentration for an MDL is obtained.MDL0.995 tStudSB(1)SB5!(i51nxi2 x!2n 2 1(2)where:MDL0.99= the method detection limit at the 99 % confidencelevel,SB= standard deviation of
43、 the mean of measuredconcentration of uranium in replicate blanks inconcentration (g/L),tStud= students t value at the 99 % confidence level forn-1 degrees of freedom (default = 3.143 for 6degrees of freedom),n = number of blanks analyzed in the study (default =7),xi= measured concentration of urani
44、um in blank “i,”x = mean of measured concentration of uranium inall replicate blanks in concentration (g/L).12.4 Method Reporting Limit (RL):12.4.1 The method reporting limit (RL) is defined as thelowest non-zero standard on the calibration curve or thecalculated MDL.12.4.2 The RL shall never be est
45、ablished at a concentrationbelow the MDL and typically is established at concentrations310 times the concentration of the measured MDL.12.5 Reporting Results:12.5.1 All sample results and reporting limits shall beadjusted for any dilutions performed.12.5.2 The sample result and associated reporting
46、limit foreach result equal to or greater than the RL shall be reported.12.5.3 Sample results measured below the low point on thecalibration curve shall be reported as “less than the reportinglimit” (for example, RL).13. Precision and Bias613.1 The collaborative test conducted on this test methodincl
47、uded six laboratories for Level 1 and seven laboratories forLevels 2 and 3. There were a total of three levels between 1 and100 g/L with three replicates per level. The determination ofthe precision and bias statements were made in accordancewith Practice D2777.13.2 These collaborative test data wer
48、e obtained usingreagent grade water. For other matrices, these data may notapply.13.3 The bias of this test method, based upon the collab-orative test data, was found to vary with level according toTable 1.13.4 The overall and single operator precision were found tovary with level according to Table
49、 2.14. Quality Control14.1 In order to be certain that analytical values obtainedusing this test method are valid and accurate within theconfidence limits of the test the following QC measures shallbe followed when running the test. The batch size should notexceed 20 samples, not including QC samples.6Supporting data have been filed at ASTM International Headquarters and maybe obtained by requesting Research Report RR:D19-1148.TABLE 1 Uranium in Water by Phosphorimetry (DigestionMethod) Bias DataAmount Added, g/L Amount Found, g/L Bias, %2.25 2.
