Improved Analysis of Petroleum and Shale-Derived Fuel Distillates by Altering GC Programmed Temperature Rates

摘要

Overlapping chromatographic peaks of components from different hydrocarbon classes can be disengaged by exploiting their shifts in relative retention behavior with changes in linear rates of programmed temperature. Many co-eluting species in complex chromatograms of shale- and petroleum-derived jet fuels can be resolved without varying stationary phase, column length, or initial column temperature. Retention indices were simultaneously determined on two bonded phase, fused silica capillary columns of slightly different polarities at three different linear programmed temperature rates. For certain hydrocarbon types, no change in index values was observed with an alteration in programming rate. However, the indices of other hydrocarbon classes shifted uniformly with programmed temperature rates on each of the two stationary phases. When applied, this phenomenon could help resolve coeluting members of different or even the same hydrocarbon type and elucidate their probable structure. The overall precision of the retention indices, i.e., the mean standard deviation at the 95% confidence levels, was less than +/- 0.13 for either column at any of three programming rates. Since the above technique is automated, it could also be a useful screening tool to search for specific hydrocarbons in a myriad of unknown components of a complex hydrocarbon mixture.