ASTM_D_6512_-_07_2014.pdf

Designation:D651207(Reapproved 2014)Standard Practice forInterlaboratory Quantitation Estimate1This standard is issued under the fixed designation D6512;the number immediately following the designation indicates the year oforiginal adoption or,in the case of 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 practice establishes a uniform standard for com-puting the interlaboratory quantitation estimate associated withZ%relative standard deviation(referred to herein as IQEZ%),and provides guidance concerning the appropriate use andapplication.The calculations involved in this practice can beperformed with DQCALC,Microsoft Excel-based softwareavailable from ASTM.21.2 IQEZ%is computed to be the lowest concentration forwhich a single measurement from a laboratory selected fromthe population of qualified laboratories represented in aninterlaboratory study will have an estimated Z%relativestandard deviation(Z%RSD,based on interlaboratory stan-dard deviation),where Z is typically an integer multiple of 10,such as 10,20,or 30,but Z can be less than 10.The IQE10%is consistent with the quantitation approaches of Currie(1)3and Oppenheimer,et al.(2).1.3 The fundamental assumption of the collaborative studyis that the media tested,the concentrations tested,and theprotocol followed in the study provide a representative and fairevaluation of the scope and applicability of the test method aswritten.Properly applied,the IQE procedure ensures that theIQE has the following properties:1.3.1 Routinely Achievable IQE ValueMost laboratoriesare able to attain the IQE quantitation performance in routineanalyses,using a standard measurement system,at reasonablecost.This property is needed for a quantitation limit to befeasible in practical situations.Representative laboratoriesmust be included in the data to calculate the IQE.1.3.2 Accounting for Routine Sources of ErrorThe IQEshould realistically include sources of bias and variation thatare common to the measurement process.These sourcesinclude,but are not limited to:intrinsic instrument noise,some“typical”amount of carryover error;plus differences inlaboratories,analysts,sample preparation,and instruments.1.3.3 Avoidable Sources of Error ExcludedThe IQEshould realistically exclude avoidable sources of bias andvariation;that is,those sources that can reasonably be avoidedin routine field measurements.Avoidable sources wouldinclude,but are not limited to:modifications to the sample;modifications to the measurement procedure;modifications tothe measurement equipment of the validated method,and grossand easily discernible transcription errors,provided there wasa way to detect and either correct or eliminate them.1.4 The IQE applies to measurement methods for whichcalibration error is minor relative to other sources,such aswhen the dominant source of variation is one of the following:1.4.1 Sample Preparation,and calibration standards do nothave to go through sample preparation.1.4.2 Differences in Analysts,and analysts have little oppor-tunity to affect calibration results(as is the case with automatedcalibration).1.4.3 Differences in Laboratories(for whatever reasons),perhaps difficult to identify and eliminate.1.4.4 Differences in Instruments(measurement equipment),such as differences in manufacturer,model,hardware,electronics,sampling rate,chemical processing rate,integra-tion time,software algorithms,internal signal processing andthresholds,effective sample volume,and contamination level.1.5 Data Quality ObjectivesTypically,one would com-pute the lowest%RSD possible for any given dataset for aparticular method.Thus,if possible,IQE10%would be com-puted.If the data indicated that the method was too noisy,onemight have to compute instead IQE20%,or possibly IQE30%.In any case,an IQE with a higher%RSD level(such asIQE50%)would not be considered,though an IQE with RSD10%(such as IQE1%)would be acceptable.The appropriatelevel of%RSD may depend on the intended use of the IQE.2.Referenced Documents2.1 ASTM Standards:41This practice is under the jurisdiction of ASTM Committee D19 onWater andis the direct responsibility of Subcommittee D19.02 on Quality Systems,Specification,and Statistics.Current edition approved Jan.15,2014.Published February 2014.Originallyapproved in 2000.Last previous edition approved in 2007 as D6512 07.DOI:10.1520/D6512-07R14.2Available fromASTM International Headquarters.OrderAdjunct No.ADJDQ-CALC.Original adjunct produced in 2007.3The boldface numbers in parentheses refer to the list of references at the end ofthis standard.4For 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 ASTM website.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,