ASTM_E_1329_-_10.pdf

Designation:E132910Standard Practice forVerification and Use of Control Charts in SpectrochemicalAnalysis1This standard is issued under the fixed designation E1329;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 covers procedures for determining if aspectrochemical analysis is under statistical control.1.2 Criteria are presented for determining when correctiveaction is required.1.3 Control will be effected by using verifiers to testinstrument response.It is recommended,although not required,that this be accompanied by the plotting of control charts.1.4 The preparation of control charts is described.1.5 LimitationsThe procedures that are described do notapply to analyses that require a calibration each time a set ofanalyses is run.Reference is made specifically to atomicemission spectrometry,but the practice has a more generalapplication.1.6 This practice does not apply to validation proceduresthat monitor the correctness of calibration.2.Referenced Documents2.1 ASTM Standards:2E135 Terminology Relating to Analytical Chemistry forMetals,Ores,and Related MaterialsE158 Practice for Fundamental Calculations to ConvertIntensities into Concentrations in Optical Emission Spec-trochemical Analysis(Withdrawn 2004)3E305 Practice for Establishing and Controlling AtomicEmission Spectrochemical Analytical CurvesE456 Terminology Relating to Quality and StatisticsE876 Practice for Use of Statistics in the Evaluation ofSpectrometric Data(Withdrawn 2003)32.2 Other ASTM Documents:MNL 7A Manual on Presentation of Data and Control ChartAnalysis43.Terminology3.1 DefinitionsFor definitions of terms used in thispractice,refer to Terminologies E135 and E456 and PracticeE876.Refer also to the glossary of terms and symbolsappearing in MNL 7A.3.2 Definitions of Terms Specific to This Standard:3.2.1 control limitsin control charts,the upper and lowerlimits of a statistic that are not expected to be exceeded,designated as UCL and LCL respectively in this practice.Forthe statistic that is the average of more than one reading ordetermination,the upper and lower limits will be equidistantfrom a central line(CL)representing the expected average.Forthe statistic of either standard deviation or range,the upperlimit will be farther from the central line if the lower limit iszero.3.2.2 normalizationa procedure for correcting readings toa common basis.A special case of normalization is standard-ization in which readings are made to conform to an existingcalibration.Normalization permits gathering data in differentperiods of time and correcting for drift in a way that may beindependent of standardization routines.3.2.3 variationdifference in an observed value from anaccepted value.3.2.3.1 assignable causevariation which can be identifiedand corrected.It may be the result of a condition of aninstrument or a method of operation.For example,signalintensities may be affected because a spectrometer is notprofiled properly.3.2.3.2 chance or common causerandom variation whichconsistently affects a system,contributing to the imprecision ina predictable way.In the application of control charts,theassumption is made that chance causes of variation arenormally distributed.1This practice is under the jurisdiction of ASTM Committee E01 on AnalyticalChemistry for Metals,Ores,and Related Materials and is the direct responsibility ofSubcommittee E01.22 on Laboratory Quality.Current edition approved Oct.1,2010.Published December 2010.Originallyapproved in 1990.Last previous edition approved in 2003 as E1329 00(2003).DOI:10.1520/E1329-10.2For 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 Document Summary page onthe ASTM website.3The last approved version of this historical standard is referenced onwww.astm.org.4ASTM Manual Series,ASTM,7th edition,2002.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 4.Significance and Use4.1 Consistency in analysis depends on being aware of asignificant change in instrumental response,such as that causedby drift or changes in analytical precision,or both,and takingcorrective action.The usual corrective action for drift isstandardization.Standardization,however,when there is noreal need,can only broaden the spread of subsequent analyses.One purpose of this practice is to set guidelines that will avoid“unnecessary standardization.”4.2 To control manufacturing processes,there must beconfidence that a consistent material is being produced and thatthe analysis of the material is reliable.For assurance that thematerial meets specification,a purchaser may require thesuppor