ASTM D6122-18
(Practice)Standard Practice for Validation of the Performance of Multivariate Online, At-Line, and Laboratory Infrared Spectrophotometer Based Analyzer Systems
Standard Practice for Validation of the Performance of Multivariate Online, At-Line, and Laboratory Infrared Spectrophotometer Based Analyzer Systems
SCOPE
1.1 This practice covers requirements for the validation of measurements made by laboratory or process (online or at-line) near- or mid-infrared analyzers, or both, used in the calculation of physical, chemical, or quality parameters (that is, properties) of liquid petroleum products and fuels. The properties are calculated from spectroscopic data using multivariate modeling methods. The requirements include verification of adequate instrument performance, verification of the applicability of the calibration model to the spectrum of the sample under test, and verification that the degree of agreement between the results calculated from the infrared measurements and the results produced by the PTM used for the development of the calibration model meets user-specified requirements. Initially, a limited number of validation samples representative of current production are used to do a local validation. When there is an adequate number of validation samples with sufficient variation in both property level and sample composition to span the model calibration space, the statistical methodology of Practice D6708 can be used to provide general validation of this equivalence over the complete operating range of the analyzer. For cases where adequate property and composition variation is not achieved, local validation continues to be used.
1.1.1 For some applications, the analyzer and PTM are applied to the same material. The application of the multivariate model to the analyzer output (spectrum) directly produces a PPTMR for the same material for which the spectrum was measured. The PPTMRs are compared to the PTMRs measured on the same materials to determine the degree of agreement.
1.1.2 For other applications, the material measured by the analyzer system is subjected to a consistent treatment prior to being analyzed by the PTM. The application of the multivariate model to the analyzer output (spectrum) produces a PPTMR for the treated material. The PPTMRs based on the analyzer outputs are compared to the PTMRs measured on the treated materials to determine the degree of agreement.
1.2 Multiple physical, chemical, or quality properties of the sample under test are typically predicted from a single spectral measurement. In applying this practice, each property prediction is validated separately. The separate validation procedures for each property may share common features, and be affected by common effects, but the performance of each property prediction is evaluated independently. The user will typically have multiple validation procedures running simultaneously in parallel.
1.3 Results used in analyzer validation are for samples that were not used in the development of the multivariate model, and for spectra which are not outliers or nearest neighbor inliers relative to the multivariate model.
1.4 When the number, composition range or property range of available validation samples do not span the model calibration range, a local validation is done using available samples representative of current production. When the number, composition range and property range of available validation samples becomes comparable to those of the model calibration set, a general validation can be done.
1.4.1 Local Validation:
1.4.1.1 The calibration samples used in developing the multivariate model must show adequate compositional and property variation to enable the development of a meaningful correlation, and must span the compositional range of samples to be analyzed using the model to ensure that such analyses are done via interpolation rather than extrapolation. The Standard Error of Calibration (SEC) is a measure of how well the PTMRs and PPTMRs agree for this set of calibration samples. SEC includes contributions from spectrum measurement error, PTM measurement error, and model error. Sample (type) specific biases are a part of the model error. Typically, spectroscopic analyzers are very precise, so that spe...
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Designation: D6122 − 18
Standard Practice for
Validation of the Performance of Multivariate Online, At-
Line, and Laboratory Infrared Spectrophotometer Based
1
Analyzer Systems
This standard is issued under the fixed designation D6122; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
INTRODUCTION
Operation of a laboratory or process stream analyzer system typically involves five sequential
activities. (1) Correlation—Prior to the initiation of the procedures described in this practice, a
multivariatemodelisderivedwhichrelatesthespectrumproducedbytheanalyzertothePrimaryTest
Method Result (PTMR). (1a) If the analyzer and Primary Test Method (PTM) measure the same
material, then the multivariate model directly relates the spectra to PTMR collected on the same
samples.Alternatively (1b) if the analyzer measures the spectra of a material that is subjected to
treatment prior to being measured by the PTM, then the multivariate model relates the spectra of
theuntreatedsampletothePTMRforthesamesampleaftertreatment. (2) Analyzer Qualification—
When an analyzer is initially installed, after major maintenance has been performed, or after the
multivariatemodelhasbeenchanged,diagnostictestingisperformedtodemonstratethattheanalyzer
meets the manufacturer’s specifications and historical performance standards. These diagnostic tests
may require that the analyzer be adjusted so as to provide predetermined output levels for certain
reference materials (3) Local Validation—A local validation is performed using an independent but
limited set of materials that were not part of the correlation activity. This local validation is intended
todemonstratethattheagreementbetweenthePredictedPrimaryMethodTestResults(PPTMRs)and
the PTMRs are consistent with expectations based on the multivariate model. (4) General
Validation—After an adequate number of PPTMRs and PTMRs have been accrued on materials that
were not part of the correlation activity and which adequately span the multivariate model
compositionalspace,acomprehensivestatisticalassessmentcanbeperformedtodemonstratethatthe
PPTMRs agree with the PTMRs to within user-specified requirements. (5) Continual Validation—
Subsequent to a successful local or general validation, quality assurance control chart monitoring of
the differences between PPTMR and PTMR is conducted during normal operation of the process
analyzer system to demonstrate that the agreement between the PPTMRs and the PTMRs established
duringtheGeneralValidationismaintained.Thispracticedealswiththethird,fourth,andfifthofthese
activities.
“Correlation where analyzer measures a material which is subjected to treatment before being
measured by the PTM” as outlined in this practice can be applied to biofuels where the biofuel
materialisaddedataterminalorotherfacilityandnotincludedintheprocessstreammaterialsampled
bytheanalyzeratthebasestockmanufacturingfacility.The“treatment”shallbeaconstantpercentage
addition of the biofuels material to the basestock material. The correlation is deemed valid only for
the specific percentage addition and type of biofuel material used in its development.
1. Scope*
1.1 This practice covers requirements for the validation of
1
This practice is under the jurisdiction ofASTM Committee D02 on Petroleum
measurementsmadebylaboratoryorprocess(onlineorat-line)
Products, Liquid Fuels, and Lubricants and is the direct responsibility of Subcom-
mittee D02.25 on Performance Assessment and Validation of Process Stream
near-ormid-infraredanalyzers,orboth,usedinthecalculation
Analyzer Systems.
ofphysical,chemical,orqualityparameters(thatis,properties)
Current edition approved July 1, 2018. Published January 2019. Originally
of liquid petroleum products and fuels. The properties are
approved in 1997. Last previous edition approved in 2015 as D6122–15. DOI:
10.1520/D6122-18. calculatedfromspectroscopicdatausingmultivariatemodeling
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
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D6122 − 18
methods. The requirements include verification of adequate PTMRs and PPTMRs agree for this set of calibration samples.
instrument performance, verification of the applicability of the SEC includes contributions from spectrum measurement error,
calibrationmodeltothespectrumofthesampleundertest,and PTM measurement error, and model error. Sample (type)
verification that the degree of agreement between the results specific biases are a part of
...
This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: D6122 − 15 D6122 − 18
Standard Practice for
Validation of the Performance of Multivariate Online, At-
Line, and Laboratory Infrared Spectrophotometer Based
1
Analyzer Systems
This standard is issued under the fixed designation D6122; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1
This practice is under the jurisdiction of ASTM Committee D02 on Petroleum Products, Liquid Fuels, and Lubricants and is the direct responsibility of Subcommittee
D02.25 on Performance Assessment and Validation of Process Stream Analyzer Systems.
Current edition approved June 1, 2015July 1, 2018. Published February 2016January 2019. Originally approved in 1997. Last previous edition approved in 20102015 as
D6122 – 13.D6122 – 15. DOI: 10.1520/D6122-15.10.1520/D6122-18.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
1
---------------------- Page: 1 ----------------------
D6122 − 18
INTRODUCTION
Operation of a laboratory or process stream analyzer system typically involves fourfive sequential
activities. (1) Correlation—Prior to the initiation of the procedures described in this practice, a
multivariate model is derived which relates the spectrum produced by the analyzer to the Primary Test
Method Result (PTMR). (1a) If the analyzer and Primary Test Method (PTM) measure the same
material, then the multivariate model directly relates the spectra to PTMR collected on the same
samples. Alternatively (1b) if the analyzer measures the spectra of a material that is subjected to
treatment prior to being measured by the PTM, then the multivariate model relates the spectra of
the untreated sample to the PTMR for the same sample after treatment. (2) Analyzer
CalibrationQualification—When an analyzer is initially installed, or after major maintenance has
been performed, or after the multivariate model has been changed, diagnostic testing is performed to
demonstrate that the analyzer meets the manufacturer’s specifications and historical performance
standards. These diagnostic tests may require that the analyzer be adjusted so as to provide
predetermined output levels for certain reference materials.materials (2a)Correlation, where analyzer
and Primary Test Method (PTM) measure the same material—Once the diagnostic testing is
completed, process stream samples are analyzed using both the analyzer system and the corresponding
PTM. A mathematical function is derived that relates the analyzer output to the PTM. The application
of this mathematical function to an analyzer output produces a Predicted Primary Test Method Result
(PPTMR) for the same material. (2b)Correlation, where analyzer measures a material which is
subjected to treatment before being measured by the PTM—Once the diagnostic testing is completed,
the process stream samples are analyzed by the analyzer system. The same samples are subjected to
a consistent treatment, and the treated samples are analyzed by the PTM. A mathematical function is
derived that related the analyzer output for the untreated sample to the Primary Test Method Result
(PTMR) for the treated material. The application of the mathematical function to the analyzer output
for the untreated material produces a PPTMR for the treated material. (3) ProbationaryLocal
Validation—Once the relationship between the analyzer output and PTMRs has been established, a
probationary —A local validation is performed using an independent but limited set of materials that
were not part of the correlation activity. This probationarylocal validation is intended to demonstrate
that the PPTMRs agree with the PTMRs to within user-specified requirements for the analyzer system
application. agreement between the Predicted Primary Method Test Results (PPTMRs) and the
PTMRs are consistent with expectations based on the multivariate model. (4) General and Continual
Validation—After an adequate number of PPTMRs and PTMRs have been accrued on materials that
were not part of the correlation activity, activity and which adequately span the multivariate model
compositional space, a comprehensive statistical assessment is can be performed to demonstrate that
the PPTMRs agree with the PTMRs to within user-specified requirements. Subsequent(5) Continual
Validation—Subsequent to a successful
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