ASTM_D_7235_-_16.pdf

Designation:D723516Standard Guide forEstablishing a Linear Correlation Relationship BetweenAnalyzer and Primary Test Method Results Using RelevantASTM Standard Practices1This standard is issued under the fixed designation D7235;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.INTRODUCTIONOperation of a process stream analyzer system typically involves four sequential activities:(1)Analyzer CalibrationWhen an analyzer is initially installed,or after major maintenance has beenperformed,diagnostic testing will typically be performed to demonstrate that the analyzer meetsmanufacturers specifications and historical performance standards.These diagnostic tests may requirethat the analyzer be adjusted so as to provide predetermined output levels for certain referencematerials.(2)Correlation to Primary Test MethodFor process stream analyzer systems where theapplication objective is to provide prediction of results from a Primary Test method,once thediagnostic testing is completed,process stream samples will typically be analyzed using both theanalyzer system and the corresponding primary test method.A mathematical function will be derivedthat relates the analyzer output to the primary test method(PTM).The application of this mathematicalfunction to an analyzer output produces a predicted PTM result.(3)Initial ValidationOnce therelationship between the analyzer output and primary test method results has been established,aninitial validation is performed using an independent data set to demonstrate that the predicted PTMresults agree with those from the primary test method within the tolerances established from theCorrelation activities and with no statistically observable systemic bias.(4)Continual ValidationDuring normal operation of the process analyzer system,quality assurance testing is conducted todemonstrate that the agreement between analyzer and primary test method results during the InitialValidation is maintained.This document provides guidance for item(2)above.1.Scope*1.1 This guide covers a general methodology to develop andassess the linear relationship between results produced by atotal analyzer system versus the results produced by thecorresponding primary test method(PTM)that the analyzersystem is intended to emulate,using the principles and ap-proaches outlined in relevant ASTM standard practices andguides.1.2 This guide describes how the statistical methodology ofPractice D6708 can be employed to assess agreement betweenthe PTM and analyzer results,and,if necessary,develop linearcorrelation to further improve the agreement over the completeoperating range of the analyzer.For instances where there isinsufficient variation in property level to apply the PracticeD6708 multi-level methodology,users are referred to PracticeD3764 to perform a level specific bias evaluation.The corre-lation relationship information obtained in the application ofthis guide is applicable only to the material type and propertyrange of the materials representative of those used to performthe assessment.Users are cautioned against extrapolation ofthe relationship beyond the material type and property rangebeing studied.1.3 This guide applies if the process stream analyzer systemand the primary test method are based on the same measure-ment principle(s),or,if the process stream analyzer systemuses a direct and well-understood measurement principle that issimilar to the measurement principle of the primary testmethod.If the process stream analyzer system uses a differentmeasurement technology from the primary test method,pro-vided that the calibration protocol for the direct output of theanalyzer does not require use of the PTM,this practice alsoapplies.1This guide is under the jurisdiction of ASTM Committee D02 on PetroleumProducts,Liquid Fuels,and Lubricants and is the direct responsibility of Subcom-mittee D02.25 on Performance Assessment and Validation of Process StreamAnalyzer Systems.Current edition approved April 1,2016.Published April 2016.Originallyapproved in 2005.Last previous edition approved in 2014 as D7235 14.DOI:10.1520/D7235-16.*A Summary of Changes section appears at the end of this standardCopyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 1.4 This guide does not apply if the process stream analyzersystem utilizes an indirect or mathematically modeled mea-surement principle such as chemometric or multivariate analy-sis techniques where results from PTM are required for thechemometric or multivariate model development.Users shouldrefer to Practices E1655 and D6122 for detailed correlation andmodel validation procedures for these types of analyzer sys-tems.NOTE1For example,this guide would apply for the comparison