ASTM E1950-17 Standard Practice for Reporting Results from Methods of Chemical Analysis.pdf
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1、Designation: E1950 17Standard Practice forReporting Results from Methods of Chemical Analysis1This standard is issued under the fixed designation E1950; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A n
2、umber in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This practice covers the approximate number of digitsrequired to express the expected precision of results reportedfrom standard methods
3、 of chemical analysis. This practiceprovides selection criteria and proper form and symbols forcoding results when necessary to indicate the relative reliabilityof results having small values.1.2 Specifically excluded is consideration of report formsand the associated informational content of report
4、s in whichresults are tabulated or transmitted. It is assumed that thereporting laboratory has established a report format to ensureproper identification of the materials tested, the nature andconditions of the test, the responsible personnel, and otherrelated information in accordance with existing
5、 regulations andgood laboratory practices.1.3 This international standard was developed in accor-dance with internationally recognized principles on standard-ization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recom-mendations issued by the Wor
6、ld Trade Organization TechnicalBarriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2E29 Practice for Using Significant Digits in Test Data toDetermine Conformance with SpecificationsE135 Terminology Relating to Analytical Chemistry forMetals, Ores, and Related MaterialsE1601
7、Practice for Conducting an Interlaboratory Study toEvaluate the Performance of an Analytical MethodE1763 Guide for Interpretation and Use of Results fromInterlaboratory Testing of Chemical Analysis Methods(Withdrawn 2015)33. Terminology3.1 Definitions:3.1.1 For definitions of terms, refer to Termino
8、logy E135.3.2 Definitions of Terms Specific to This Standard:3.2.1 lower limit, L, nthe lower limit of the quantitativeanalyte mass fraction or concentration range (see Annex A1).3.2.2 low-level reproducibility index, KR,nthe reproduc-ibility index constant (for low analyte levels) determined asdire
9、cted by Guide E1763.3.2.3 null limit, NL, nthe analyte content below whichresults are so near zero that averaging is unlikely to yield avalue significantly different from zero.3.2.4 quantitative, adjrelating to results, having a numeri-cal value that includes at least one significant digit (see Prac
10、ticeE29).4. Significance and Use4.1 Aresult must be stated to a sufficient number of digits sothat a user receives both quantitative information and ameasure of the variability of the value reported.4.2 The range of application of most methods of chemicalanalysis is based upon the presumption that t
11、he quantitativeresults produced are to be used to compare the analyte contentof the test material with specified limiting values. However,analytical results may be used legitimately for other purposes.If the same material is analyzed a number of times or a productis analyzed periodically during an i
12、nterval of production, eachset of results may be averaged to yield an average result havingimproved reliability, provided nothing has been done betweenanalyses to modify the composition of the analyzed material.Results that fall below the lower limit, although not quantita-tive individually, contain
13、 compositional information and maybe reported. The reporting system in this practice permits theanalyst to indicate which values are likely to be renderedquantitative by averaging and which are not.1This practice is under the jurisdiction of ASTM Committee E01 on AnalyticalChemistry for Metals, Ores
14、, and Related Materials and is the direct responsibility ofSubcommittee E01.22 on Laboratory Quality.Current edition approved Nov. 15, 2017. Published December 2017. Originallyapproved in 1998. Last previous edition approved in 2010 as E1950 10. DOI:10.1520/E1950-17.2For referenced ASTM standards, v
15、isit 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 ASTM website.3The last approved version of this historical standard is referenced onwww.astm.org.Copyright
16、ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United StatesThis international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for theDevelopment of International S
17、tandards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.14.3 The system is simple enough to be used routinely inreporting results from standard methods and assists thoseuntrained in statistics to apply results appropriately.5. Rounding
18、Calculated Values5.1 Use information from the precision section of themethod to determine the appropriate number of digits to reportas follows:5.1.1 Estimate the reproducibility index, R, at the analytelevel of the result, C, from an equation of R as a function ofconcentration or mass fraction, or f
19、rom the table of statisticalinformation.5.1.2 Calculate the percent relative reproducibility index:Rrel%5 100 3R/C (1)5.1.3 For results within the range of application specified inthe method, round the values to the number of digits specifiedin Table 1 (see A1.1.1 through A1.1.2).5.1.4 For results l
20、ess than the lower limit, proceed asdirected in Section 6 to establish the number of digits andappropriate coding for rounding and reporting the values.5.2 Calculated values shall be rounded to the requirednumber of digits in accordance with the rounding method ofPractice E29.6. Procedure6.1 Prelimi
21、nary PrecautionFor a method to be used toanalyze materials with analyte content very near zero, theanalyst shall determine that it is capable of producing “unbi-ased” estimates of zero. If the method occasionally yieldsnegative results for low analyte levels, that capability isdemonstrated. Proceed
22、as directed in 6.2.6.1.1 Test for “Biased-Zero” MethodsPrepare the methodto perform determinations. Include all aspects of instrumentpreparation and calibration. Apply the method to a “blank”sample or one known to have negligible analyte content butthat meets the methods scope requirements in all ot
23、herrespects. If the method yields a negative result, it is not a“biased-zero” method as directed in 6.2. If, during the courseof at least ten replicate determinations, several zeros but nonegative values are observed, it is a “biased-zero” method.Apply the biased-zero rule of 6.4 in reporting result
24、s lowerthan NL (see 6.2.2).6.2 Critical Concentrations or Mass Fractions:6.2.1 From the method, obtain the value of the lower limit,L, to two digits (add a final zero, if necessary). Determine thedecimal place of the second digit.6.2.2 Calculate the null limit as follows:NL 5 L/4 (2)6.3 Basic Rules:
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