ASTM D6122-09
(Practice)Standard Practice for Validation of the Performance of Multivariate Process Infrared Spectrophotometers
Standard Practice for Validation of the Performance of Multivariate Process Infrared Spectrophotometers
SIGNIFICANCE AND USE
The primary purpose of this practice is to permit the user to validate numerical values produced by a multivariate, infrared or near-infrared, online, process analyzer calibrated to measure a specific chemical concentration, chemical property, or physical property. The validated analyzer results are expected to be equivalent, over diverse samples whose spectra are neither outliers or nearest neighbor inliers, to those produced by the primary test method to within control limits established by control charts for the prespecified statistical confidence level.
Procedures are described for verifying that the instrument, the model, and the analyzer system are stable and properly operating.
A multivariate analyzer system inherently utilizes a multivariate calibration model. In practice the model both implicitly and explicitly spans some subset of the population of all possible samples that could be in the complete multivariate sample space. The model is applicable only to samples that fall within the subset population used in the model construction. A sample measurement cannot be validated unless applicability is established. Applicability cannot be assumed.
Outlier detection methods are used to demonstrate applicability of the calibration model for the analysis of the process sample spectrum. The outlier detection limits are based on historical as well as theoretical criteria. The outlier detection methods are used to establish whether the results obtained by an analyzer are potentially valid. The validation procedures are based on mathematical test criteria that indicate whether the process sample spectrum is within the range spanned by the analyzer system calibration model. If the sample spectrum is an outlier, the analyzer result is invalid. If the sample spectrum is not an outlier, then the analyzer result is valid providing that all other requirements for validity are met. Additional, optional tests may be performed to determine if the process sample spectrum ...
SCOPE
1.1 This practice covers requirements for the validation of measurements made by online, process near- or mid-infrared analyzers, or both, used in the calculation of physical, chemical, or quality parameters (that is, properties) of liquid petroleum products. 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 of equivalence between the result calculated from the infrared measurements and the result produced by the primary test method used for the development of the calibration model. When there is adequate variation in property level, the statistical methodology of Practice D 6708 is used to provide general validation of this equivalence over the complete operating range of the analyzer. For cases where there is inadequate property variation, methodology for level specific validation is used.
1.2 Performance Validation is conducted by calculating the precision and bias of the differences between results from the analyzer system (or subsystem) produced by application of the multivariate model, (such results are herein referred to as Predicted Primary Test Method Results (PPTMRs)), versus the Primary Test Method Results (PTMRs) for the same sample set. Results used in the calculation are for samples that are not used in the development of the multivariate model. The calculated precision and bias are statistically compared to user-specified requirements for the analyzer system application.
1.2.1 For analyzers used in product release or product quality certification applications, the precision and bias requirement for the degree of agreement are typically based on the site or published precision of the Primary Test Method.
Note 1—In most applications of this type, the PTM is the specificati...
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Designation:D6122–09
Standard Practice for
Validation of the Performance of Multivariate Process
1
Infrared Spectrophotometer Based 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 process stream analyzer system typically involves four sequential activities.
(1)Analyzer Calibration—When an analyzer is initially installed, or after major maintenance has
been performed, diagnostic testing is performed to demonstrate that the analyzer meets the
manufacturer’sspecificationsandhistoricalperformancestandards.Thesediagnostictestsmayrequire
that the analyzer be adjusted so as to provide predetermined output levels for certain reference
materials. (2)Correlation—Once the diagnostic testing is completed, process stream samples are
analyzed using both the analyzer system and the corresponding primary test method (PTM). A
mathematical function is derived that relates the analyzer output to the primary test method (PTM).
The application of this mathematical function to an analyzer output produces a predicted primary test
method result (PPTMR). (3)Probationary Validation—Once the relationship between the analyzer
outputandPTMRshasbeenestablished,aprobationaryvalidationisperformedusinganindependent
but limited set of materials that were not part of the correlation activity. This probationary validation
is intended to demonstrate that the PPTMRs agree with the PTMRs to within user-specified
requirements for the analyzer system application. (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, a comprehensive statistical assessment is performed to demonstrate that the
PPTMRs agree with the PTMRs to within user-specified requirements. Subsequent to a successful
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 during the General Validation is
maintained. This practice deals with the third and fourth of these activities.
1. Scope of equivalence between the result calculated from the infrared
measurements and the result produced by the primary test
1.1 This practice covers requirements for the validation of
method used for the development of the calibration model.
measurements made by online, process near- or mid-infrared
When there is adequate variation in property level, the statis-
analyzers, or both, used in the calculation of physical, chemi-
ticalmethodologyofPracticeD6708isusedtoprovidegeneral
cal, or quality parameters (that is, properties) of liquid petro-
validation of this equivalence over the complete operating
leum products. The properties are calculated from spectro-
range of the analyzer. For cases where there is inadequate
scopic data using multivariate modeling methods. The
property variation, methodology for level specific validation is
requirements include verification of adequate instrument per-
used.
formance, verification of the applicability of the calibration
1.2 Performance Validation is conducted by calculating the
modeltothespectrumofthesampleundertest,andverification
precision and bias of the differences between results from the
analyzer system (or subsystem) produced by application of the
1
This practice is under the jurisdiction ofASTM Committee D02 on Petroleum
multivariate model, (such results are herein referred to as
ProductsandLubricantsandisthedirectresponsibilityofSubcommitteeD02.25on
PredictedPrimaryTestMethodResults(PPTMRs)),versusthe
Performance Assessment and Validation of Process Stream Analyzer Systems.
Primary Test Method Results (PTMRs) for the same sample
CurrenteditionapprovedJune1,2009.PublishedJuly2009.Originallyapproved
´1
in 1997. Last previous edition approved in 2006 as D6122–06 . DOI: 10.1520/
set. Results used in the calculation are for samples that are not
D6122-09.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
1
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D6122–09
used in the development of the multivariate model. The 2. Referenced Documents
2
calculated precision and bias are statistically compared to
2.1 ASTM Standards:
user-specified requirements for the analyzer system applica-
D1265 Practice for Sampling Liquefied Petroleum (LP)
tion.
Gases, Manual Method
1.2.1 For analyzers used i
...
This document is not anASTM standard and is intended only to provide the user of anASTM 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.
´1
Designation:D6122–06 Designation:D6122–09
Standard Practice for
Validation of the Performance of Multivariate Process
Infrared SpectrophotometersValidation of the Performance
of Multivariate Process 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.
1
´ NOTE—Updated Fig. 4 editorially in November 2006.
INTRODUCTION
Operation of a process stream analyzer system typically involves four sequential activities.
(1)Analyzer Calibration —When an analyzer is initially installed, or after major maintenance has
been performed, diagnostic testing is performed to demonstrate that the analyzer meets the
manufacturer’sspecificationsandhistoricalperformancestandards.Thesediagnostictestsmayrequire
that the analyzer be adjusted so as to provide predetermined output levels for certain reference
materials. (2)Correlation—Once the diagnostic testing is completed, process stream samples are
analyzed using both the analyzer system and the corresponding primary test method (PTM). A
mathematical function is derived that relates the analyzer output to the primary test method (PTM).
The application of this mathematical function to an analyzer output produces a predicted primary test
method result (PPTMR). (3) Probationary Validation—Once the relationship between the analyzer
outputandPTMRshasbeenestablished,aprobationaryvalidationisperformedusinganindependent
but limited set of materials that were not part of the correlation activity. This probationary validation
is intended to demonstrate that the PPTMRs agree with the PTMRs to within user-specified
requirements for the analyzer system application. (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, a comprehensive statistical assessment is performed to demonstrate that the
PPTMRs agree with the PTMRs to within user-specified requirements. Subsequent to a successful
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 during the General Validation is
maintained. This practice deals with the third and fourth of these activities.
1. Scope
1.1 This practice covers requirements for the validation of measurements made by online, process near- or mid-infrared
analyzers, or both, used in the calculation of physical, chemical, or quality parameters (that is, properties) of liquid petroleum
products. 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 of equivalence between the result calculated from the infrared measurements and the result
produced by the primary test method used for the development of the calibration model. When there is adequate variation in
property level, the statistical methodology of Practice D6708 is used to provide general validation of this equivalence over the
complete operating range of the analyzer. For cases where there is inadequate property variation, methodology for level specific
validation is used.
1.2 Performance Validation is conducted by calculating the precision and bias of the differences between results from the
1
This practice is under the jurisdiction of ASTM Committee D02 on Petroleum Products and Lubricants and is the direct responsibility of Subcommittee D02.25 on
Performance Assessment and Validation of Process Stream Analyzer Systems for Petroleum and Petroleum Products.
Current edition approved July 1, 2006. Published August 2006. Originally approved in 1997. Last previous edition approved in 2001 as D6122–01.on Performance
Assessment and Validation of Process Stream Analyzer Systems.
´1
Current edition approved June 1, 2009. Published July 2009. Originally approved in 1997. Last previous edition approved in 2006 as D6122–06 .
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United
...
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