Micro gas chromatography sample injector for the analysis of natural gas

This paper reports on a gas sample injection system for gas chromatography, with the specificity of being potentially able to sustain the harsh environment of natural gas. This device integrates six low-leak microvalves made from polyetheretherketone (PEEK) membranes on silicon substrates. We report on the design, operation principle, fabrication, and intrinsic characteristics of the micro injector as well as its measured behavior in a compact gas chromatograph. The overall size of the micro injector - 7 mm × 3 mm × 1.2 mm - is among the smallest reported in the literature, and it permits the injection of a 250-nL sample volume. Characterization revealed a transition time of less than 35 ms between the sampling mode and the injection mode of the microinjector, with an expected potential of high precision on injection sample volume, owing to the very low leakage levels. Continuous operation and reproducible measurements are demonstrated when using the micro injector in a miniaturized chromatographic system. Comparison with commercially available injectors revealed similar quality of gas sample injection.