1、Designation:D625915An American National StandardStandard Practice forDetermination of a Pooled Limit of Quantitation for a TestMethod1This standard is issued under the fixed designation D6259;the number immediately following the designation indicates the year oforiginal adoption or,in the case of re
2、vision,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.Scope*1.1 This practice covers the use of standard regressiontechniques and data from an interlaboratory study to
3、 determinea lower quantitative limit for a test method.This determinedlower limit represents the numerical limit at or above which thetest results are considered to be quantitatively meaningful forcommerce or regulatory activities by this practice.It is definedby this standard as the pooled limit of
4、 quantitation(PLOQ)forthe test method.1.2 This practice is applicable to test methods that arecapable of producing numerical test results close to zero.Examples are those test methods that determine quantitativelythe concentration of analyte(s)near zero.2.Referenced Documents2.1 ASTM Standards:2D630
5、0 Practice for Determination of Precision and BiasData for Use in Test Methods for Petroleum Products andLubricantsE456 Terminology Relating to Quality and StatisticsE691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test Method3.Terminology3.1 Definitions:3.1.1 rep
6、eatability conditions,nconditions under whichtest results are obtained with the same test method in the samelaboratory by the same operator with the same equipment in theshortest practical period of time using test units or testspecimens taken at random from a single quantity of materialthat is as n
7、early homogeneous as possible.NOTE1By in the shortest practical period of time is meant that thetest results,at least for one material,are obtained in a time period not lessthan in normal testing and not so long as to permit significant change intest material,equipment,or environment.See Terminology
8、 E456.3.2 Definitions of Terms Specific to This Standard:3.2.1 pooled limit of quantitation(PLOQ),nlevel ofproperty or concentration for a test method at which the ratio:10 pooled repeatability standard deviation of results for aconcentration level/concentration level=1.3.2.1.1 DiscussionQuantitativ
9、e test results obtained usinga test method at or below its PLOQ is expected to have anuncertainty of 630%or greater at the 95%confidence level.3.2.2 pooled repeatability standard deviation,nthe statis-tically pooled standard deviation for results obtained underrepeatability conditions over multiple
10、operators/laboratoriesfor a sample that is obtained in accordance with PracticeD6300 or other equivalent Interlaboratory Study(ILS)analysis(for example,Practice E691,ISO 4259).3.2.3 laboratory limit of quantitation(LLOQ),nlevel ofproperty or concentration for a test method at which the ratio:10 repe
11、atability standard deviation of results for a concen-tration level determined in a single laboratory/concentrationlevel=1.3.2.3.1 DiscussionQuantitative test results obtained bythis single laboratory at or below its LLOQ is expected to havean uncertainty of 630%or greater at the 95%confidencelevel.3
12、.3 Acronyms:3.3.1 ILS,ninterlaboratory study.3.3.2 LLOQ,nlaboratory limit of quanitation.3.3.3 PLOQ,npooled limit of quantitation.4.Summary of Practice4.1 Statistically pooled repeatability standard deviationsfrom multiple laboratories for at least seven samples meetingthe requirements in Section 6
13、are obtained.4.2 An empirical power function is fitted to the plot Y versusX where:Y=10 pooled repeatability standard deviation/mean foreach sample,andX=mean of each sample.1This practice is under the jurisdiction of Committee D02 on PetroleumProducts,Liquid Fuels,and Lubricantsand is the direct res
14、ponsibility of Subcom-mittee D02.94 on Coordinating Subcommittee on Quality Assurance and Statistics.Current edition approved July 1,2015.Published August 2015.Originallyapproved in 1998.Last previous edition approved in 2010 as D6259 98(2010).DOI:10.1520/D6259-15.2For referenced ASTM standards,visi
15、t 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.*A Summary of Changes section appears at the end of this standardCopyright ASTM International,100 Bar
16、r Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 4.3 The value of X at which the evaluated Y=1 isdetermined using the function determined in 4.2.This value ofX is defined as the PLOQ for the method.5.Significance and Use5.1 BackgroundIn a single laboratory,the limit ofquantitation,LOQ,equal to ten times the standard deviationobtained under repeatability conditions extrapolated to zeroconcentration(s0)based on samples with close to zero concen-trations has been recommende