2010 Volume 89 Issue 5 Pages 456-462
International Bureau of Weights and Measures (BIPM) - Consultative Committee for Amount of Substance (CCQM) has conducted international comparisons on quantitative analysis of natural gas components. We participated in one of the international key comparisons for natural gas analysis, CCQM-K23b, as National Metrology Institute of Japan. A pilot laboratory of this comparison distributed the sample gas cylinders to 16 participants (including the pilot laboratory). Nominal composition of sample gases in this comparison was 70 mmol/mol of nitrogen, 30 mmol/mol of carbon dioxide, 94 mmol/mol of ethane, 34 mmol/mol of propane, 10 mmol/mol of isobutane, 8 mmol/mol of butane. The other component gas was methane. In order to measure the sample gas, we prepared our own primary reference gas mixtures by gravimetric blending method. After that, we measured each component in the sample gas with micro gas chromatograph. The accuracy of analyzed concentrations by us were 0.079 to 0.27% as relative expanded uncertainties (coverage factor, k=2). These uncertainties were enough small to participate in this comparison, because the uncertainties were close to those of key comparison reference values for the sample gas. Furthermore, our analytical results had consistency with the results of other national metrology institutes.
