Supercritical Fluid Chromatography Method Research Articles

Supercritical fluid chromatographic determination of hydrocarbon groups in gasolines and middle distillate fuels

A supercritical fluid chromatographic method to determine the percentage of saturates, olefins, and aromatics in gasolines and middle distillate fuels was developed. A microbore (1 mm i.d.) silica gel column was used to isolate and determine the aromatics, while a silver-ion-loaded strong cation exchange silica gel microbore column was used to separate the saturates from the olefins and aromatics. Olefins were determined by difference or by using a column switching technique which allows complete separation of saturates, olefins, and aromatics in a single run. A mixed mobile phase of 10% CO/sub 2/ in SF/sub 6/ (mole percent) was used for both columns, and a flame ionization detector provided uniform, linear response of the hydrocarbons, allowing quantitation with minimal calibration. The average absolute error was 1.5%, while the standard deviation of the area percent of the aromatics of one gasoline sample was 0.5%. Analysis times of under 60 min were achieved.

A study of retention characteristics by functional group analysis using supercritical fluid chromatography

Supercritical fluid chromatography (SFC) has recently been applied to the analysis of agricultural compounds. Studies investigating factors governing retention behavior of the compounds of interest will facilitate SFC method development for new compounds and metabolites. In this study, several compounds containing various functional groups were examined. Initial trends in retention were established; where appropriate, retention behavior was correlated with functional group similarities, differences and regio chemistry of compounds containing the same functional groups. Packed and capillary column SFC were used in these analyses. Results were compared to retention behavior observed under reversed-phase HPLC conditions. In general, the normal phase characteristics of SFC are very desirable in the separation of more polar compounds and metabolites of the agricultural products. Regio chemical effects and additions of methyl, phenyl, nitro, amide, carboxamide, chloro and other functional groups to common base molecules are discussed.