Value assignment and uncertainty evaluation for certified reference gas mixtures

Published

September 9, 2024

Author(s)

Christina Cecelski, Jennifer Carney, Antonio Possolo

Abstract

The procedures used to assign values to certified reference gas mixtures and to evaluate their associated uncertainties, which are described in ISO 6143, and that were variously improved by Guenther and Possolo (Anal Bioanal Chem 399:489–500, 2011. 10.1007/s00216-010-4379-z), are further enhanced by the following developments: (i) evaluating and propagating uncertainty contributions derived from comparisons with historical reference gas mixtures of similar nominal composition; (ii) recognizing and quantifying mutual inconsistency (dark uncertainty) between primary standard gas mixtures used for calibration; (iii) employing Bayesian procedures for calibration, value assignment, and uncertainty evaluations; and (iv) employing state-of-the-art methods of meta-analysis to combine cylinder-specific measurement results. These developments are illustrated in examples of certification of two gas mixture Standard Reference Materials developed by the National Institute of Standards and Technology (NIST, USA). These examples serve only to demonstrate the methods described in this contribution and do not replace any official measurement results delivered in the certificates of any reference materials developed by NIST.

Citation

Accreditation and Quality Assurance

Pub Type

Journals

Download Paper

https://doi.org/10.1007/s00769-024-01614-w

Local Download

Keywords

calibration, gas mixture, certified reference material, errors-in-variables regression, maximum likelihood, Bayesian methods, homogeneity, dark uncertainty, prediction

Citation

Cecelski, C. , Carney, J. and Possolo, A. (2024), Value assignment and uncertainty evaluation for certified reference gas mixtures, Accreditation and Quality Assurance, [online], https://doi.org/10.1007/s00769-024-01614-w, https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=956579 (Accessed October 17, 2025)