ASTM_E_2054_-_99.pdf

Designation:E 2054 99Practice forPerformanceBased Description of Instruments in ChemicalAnalysis Methods1This standard is issued under the fixed designation E 2054;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(e)indicates an editorial change since the last revision or reapproval.1.Scope1.1 This practice covers procedures for specifying instru-ments for chemical analysis by performance rather than bydesign.1.2 The provisions of this practice do not apply to classicalchemical method of analysis.2.Referenced Documents2.1 ASTM Standards:E 135 Terminology Relating to Analytical Chemistry forMetals,Ores,and Related Materials2E 396 Test Method for Chemical Analysis of Cadmium3E 1024 Guide for Chemical Analysis of Metals and MetalBearing Ores by Flame Atomic Absorption Spectropho-tometry3E 1601 Practice for Conducting an Interlaboratory Study toEvaluate the Performance of an Analytical Method3E 1763 Guide for Interpretation and Use of Results fromInterlaboratory Testing of Chemical Analysis Methods3E 1914 Practice for the Use of Terms Relating to theDevelopment and Evaluation of Methods of ChemicalAnalysis3E 2055 Practice for Referencing Methods for ChemicalAnalysis of Metals and Related Materials33.Terminology3.1 DefinitionsFor definitions and use of terms used inthis practice,refer to Terminology E 135 and Practice E 1914.3.2 Definitions of Terms Specific to This Standard:3.2.1 classical analytical method,na method based uponclassical analytical measurements,that is,weight(as byanalytical balance),volume(as by buret),or both.3.2.2 instrumental analytical method,na method basedupon analytical measurements other than those employed inclassical methods.3.2.3 minimum instrument sensitivity index,MISI,nafigure of merit used to compare sensitivity of instruments atlow analyte levels.3.2.4 relative instrument sensitivity index,RISI,na figureof merit used to compare sensitivity of instruments at elevatedanalyte levels.4.Summary of Practice4.1 The author or a task group conducting an interlaboratorystudy(ILS)examines a measuring instrument to determinewhich components and operations contribute to imprecision ofresults.The task group collects ILS data and calculates valuesfor criteria that define acceptable operation of those compo-nents.Instrument tests and critical values are written into theApparatus section.Before applying a method,users verify thatan instrument meets the specified performance criteria.5.Significance and Use5.1 Instrumental methods specify measurement apparatusby name and a brief design description.An instrument de-signed differently than described may provide equivalentmeasurements.Relying solely on design specifications some-times excludes instruments capable of the required perfor-mance.5.2 This practice requires each method to specify tests andcriteria to measure critical performance characteristics of aninstrument.The tests provide verification that a users instru-ment is capable of producing results that reflect the precisionstated in the method.5.3 Any instrument designed to measure the physical prop-erties in the specified analytical systems may be used in amethod if it meets the performance criteria.If an instrumentsperformance does not meet the criteria,a user may still applythe method,but is warned that results may have greatervariability than is specified in the method.(WarningMeeting instrument performance criteria does not guaranteeexpected precision and accuracy.The tests warn only ofexcessive instrumental error.A user shall employ referencematerials in accordance with Practice E 2055 and adherestrictly to all requirements of a method to obtain results inaccordance with its Precision and Bias section.5.4 Classical analytical methods are not covered by thispractice.1This practice is under the jurisdiction of ASTM Committee E-1 on AnalyticalChemistry for Metals,Ores,and Related Materials and is the direct responsibility ofSubcommittee E01.22 on Statistics and Quality Control.Current edition approved Dec.10,1999.Published February 2000.2Annual Book of ASTM Standards,Vol 03.05.3Annual Book of ASTM Standards,Vol 03.06.1Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959,United States.6.Minimum Performance Parameters6.1 In instrumental methods,results are calculated from aninstruments response to an analytes concentration.Readingsare visually estimated values from an instruments analog scaleor digital values derived mechanically or electronically from itsoutput.A method specifies manual calculation of results frominstrument readings or programmed calculation by a computer.Some instruments may be calibrated to provide readingsdirectly in analyte content or concentration.In any case,amethod specifies one instrument sensitivity index near thebottom and another near the top of an