Quantification of the C30+ fraction of North sea gas condensates by high temperature capillary gas chromatography
Abstract
Good reproducibility and quantitative analysis of high molecular mass n-alkanes by high temperature capillary gas chromatography (HTCGC) is attainable. For the authentic n-alkanes, the method described in this paper gave for C20–C60, an sr of under 5% for manual injection, a linear response factor and a linear calibration over the concentrations used. When applied to the analysis of two waxy North Sea gas condensates, n-alkanes with carbon numbers extending above C80 were observed. This is a surprising result because condensates are generally low molecular mass fluids similar to gasoline. Good quantitative agreement was observed between HTCGC and conventional gas chromatography for carbon fractions less than C30 but HTCGC was able to extend the quantitative analysis to carbon numbers of at least C65.