Determination of low levels of methanol in crude oils by multi-dimensional gas chromatography (MDGC) using novel micro channel flow technology.

The accurate and precise determination of methanol in crude oils at concentrations less than 10 ppm is of economic value to the petroleum industry. This report presents the optimization, results and long term performance of a flow switching device MDGC hardware, the Swafer™, for the rapid and precise analysis of methanol from approximately 0.4 ppm (w/w) to 1000 ppm. The use of low temperature injection and backflush technique decreases maintenance and increases sample throughput. The short term quantitative percent relative standard deviations at 1, 30 and 1000 ppm (w/w) methanol in crude oils are 5, 3 and 0.3, respectively. The MDGC procedure follows closely that described in ASTM D7059 for determination of crude oils; however, D7059 previously has not been evaluated at concentrations of less than 10 ppm. This work further extends the application of D7059 to concentrations of <10 ppm.