Abstract. Twenty-two standards of synthetic natural gas standards were submitted from ten different NMIs for a comparison using the harmonization method developed by NPL. All standards had seven components. This method can remove the correlated variation in calibration data for multi-component mixtures and makes a significant improvement in fitting individual points to calibration curves. After removing the non-random variation from the data all the standards showed very good agreement with only a few outliers. The typical deviation from the calibration curves was around 0.05% (relative) for the main components and less than 0.2% for the butanes.

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