Ultra-Fast Determination of the Hydrocarbon Oil Index by Gas Chromatography using LTM GC
Ultra-fast gas chromatographic methods for determination of the hydrocarbon oil index according to ISO 9377-2 were developed using a low thermal mass column heater (LTM). The column heater consists of a module that enables very fast and controlled heating of the capillary column. The speed of analysis for the hydrocarbon group eluting between C10 and C40 could in this way be increased by up to a factor 18 compared to the conventional method. Since the column can also be cooled very quickly, the total cycle time can be reduced to less than 2 minutes. In addition to ultra-fast screening and a fully compliant method, an analytical method was developed that allows the separation of groups of hydrocarbons eluting between n-C10 and n-C20, n-C20 and n-C30, and n-C30 and n-C40, respectively. The cycle time for this analysis was 4.5 min. The quantitative performance of chromatographic analysis, with respect to linearity and sensitivity, is comparable to the conventional method.