ASTM D 7235 : 2021 : REV A

1.1This guide covers a general methodology to develop and assess the linear relationship between results produced by a total analyzer system versus the results produced by the corresponding primary test method (PTM) that the analyzer system is intended to emulate, using the principles and approaches outlined in relevant ASTM standard practices and guides.

1.2This guide describes how the statistical methodology of Practice D6708 can be employed to assess agreement between the PTM and analyzer results, and, if necessary, develop linear correlation to further improve the agreement over the complete operating range of the analyzer. For instances where there is insufficient variation in property level to apply the Practice D6708 multi-level methodology, users are referred to Practice D3764 to perform a level specific bias evaluation. The correlation relationship information obtained in the application of this guide is applicable only to the material type and property range of the materials representative of those used to perform the assessment. Users are cautioned against extrapolation of the relationship beyond the material type and property range being studied.

1.3This guide applies if the process stream analyzer system and the primary test method are based on the same measurement principle(s), or, if the process stream analyzer system uses a direct and well-understood measurement principle that is similar to the measurement principle of the primary test method. If the process stream analyzer system uses a different measurement technology from the primary test method, provided that the calibration protocol for the direct output of the analyzer does not require use of the PTM, this practice also applies.

1.4This guide does not apply if the process stream analyzer system utilizes an indirect or mathematically modeled measurement principle such as chemometric or multivariate analysis techniques where results from PTM are required for the chemometric or multivariate model development. Users should refer to Practices D8321 and D6122 for detailed correlation and model validation procedures for these types of analyzer systems.

1.5This guide assumes that the analyzer sampling system is fit for use, and both analyzer and lab systems are in statistical control during the execution of the required tasks. Procedures for testing for proper function of the analyzer sampling system are beyond the scope of this guide. For ascertaining whether the systems are in statistical control, refer to Practice D6299 or other technical equivalent documents.

1.6This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.

1.7This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.