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Calibration and uncertainty assessment for certified reference gas mixtures
Franklin R Guenther1, Antonio Possolo
1Material Measurement Laboratory, Analytical Chemistry Division, Gas Metrology Group, National Institute of Standards and Technology, 100 Bureau Drive, Stop 8393, Gaithersburg, MD 20899-8393, USA. franklin.guenther@nist.gov
Analytical and Bioanalytical Chemistry
|November 13, 2010
Summary
A modified weighted least squares method improves calibration gas mixture analysis by accounting for limited data. This approach enhances uncertainty assessment using Monte Carlo methods for more reliable gas mixture certification.
Area of Science:
- Analytical Chemistry
- Metrology
- Gas Analysis
Background:
- Accurate calibration gas mixtures are essential for precise gas analysis.
- ISO 6143 provides a method for building analysis functions but has limitations with small datasets.
- Traditional uncertainty propagation can be complex and require approximations.
Purpose of the Study:
- To modify the weighted least squares method for improved analysis of calibration gas mixtures with limited instrumental readings.
- To develop a robust uncertainty assessment method for gas mixture certification.
- To illustrate the practical application of the enhanced method using real-world data.
Main Methods:
- Modification of the weighted least squares method from ISO 6143.
- Application of Monte Carlo method for uncertainty assessment, aligned with GUM Supplement 1.
- Simulation study using real data from a standard reference material.
Main Results:
- The modified weighted least squares method demonstrates superior performance compared to conventional approaches.
- The Monte Carlo method provides a more direct and reliable uncertainty assessment.
- The study successfully illustrates NIST's three-step certification process for reference gas mixtures.
Conclusions:
- The enhanced method offers a more accurate way to build analysis functions for calibration gas mixtures.
- Monte Carlo simulation simplifies and improves the reliability of uncertainty evaluation.
- The described methodology enhances the certification of standard reference gas mixtures.
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