ASTM D6122-13
(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
SIGNIFICANCE AND USE
5.1 The primary purpose of this practice is to permit the user to validate numerical values produced by a multivariate, infrared or near-infrared laboratory or process (online or at-line) 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.
5.2 Procedures are described for verifying that the instrument, the model, and the analyzer system are stable and properly operating.
5.3 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.
5.3.1 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 performe...
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. 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 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...
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Designation: D6122 − 13
StandardPractice 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 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’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. (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).Amathematical 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 output and PTMRs has been established, a probationary validation is performed using an
independentbutlimitedsetofmaterialsthatwerenotpartofthecorrelationactivity.Thisprobationary
validationisintendedtodemonstratethatthePPTMRsagreewiththePTMRstowithinuser-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.
measurementsmadebylaboratoryorprocess(onlineorat-line)
When there is adequate variation in property level, the statis-
near-ormid-infraredanalyzers,orboth,usedinthecalculation
ticalmethodologyofPracticeD6708isusedtoprovidegeneral
ofphysical,chemical,orqualityparameters(thatis,properties)
validation of this equivalence over the complete operating
of liquid petroleum products. The properties are calculated
range of the analyzer. For cases where there is inadequate
from spectroscopic data using multivariate modeling methods.
property variation, methodology for level specific validation is
The requirements include verification of adequate instrument
used.
performance, verification of the applicability of the calibration
modeltothespectrumofthesampleundertest,andverification
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
1
This practice is under the jurisdiction ofASTM Committee D02 on Petroleum
multivariate model, (such results are herein referred to as
Products, Liquid Fuels, and Lubricants and is the direct responsibility of Subcom-
mittee D02.25 on Performance Assessment and Validation of Process Stream
PredictedPrimaryTestMethodResults(PPTMRs)),versusthe
Analyzer Systems.
Primary Test Method Results (PTMRs) for the same sample
Current edition approved May 1, 2013. Published June 2013. Originally
set. Results used in the calculation are for samples that are not
approved in 1997. Last previous edition approved in 2010 as D6122–10. DOI:
10.1520/D6122-13. used in the development of the multivariate model. The
*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
1
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D6122 − 13
calculated precision and bias are statistically compared to 2. Referenced Documents
user-specified requirements for the analyzer system applica
...
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 − 10 D6122 − 13
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.
INTRODUCTION
Operation of a laboratory or 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’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. (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 output and PTMRs has been established, a probationary validation is performed using an
independent 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 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. 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
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
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.
Current edition approved May 1, 2010May 1, 2013. Published May 2010June 2013. Originally approved in 1997. Last previous edition approved in 20092010 as
D6122D6122 – 10.–09. DOI: 10.1520/D6122-10.10.1520/D6122-13.
*A Summary of Changes section appears at the end of this standard
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