TYPE ANALYSIS OF CITRUS ESSENTIAL OILS BY MULTIDIMENSIONAL SUPERCRITICAL-FLUID CHROMATOGRAPHY GAS-CHROMATOGRAPHY

A multidimensional supercritical fluid chromatography (SFC)/gas chromatography (GC) system was developed for the characterization of citrus essential oils. For on-line coupling of SFC with GC, the carbon dioxide mobile phase used in the SFC was split after a UV detector and then introduced into a GC injector. The elution order in the SFC on a silica-gel column was based on the polarities of the solutes. First, citrus essential oils were separated into three fractions (hydrocarbons, aldehydes and esters, and alcohols) by SFC utilizing stepwise pressure programming. Then, each fraction was introduced into the GC and determined using a flame ionization detector for the quantification of three fractions as well as their components in the oils. The SFC/GC system was applied to the characterization of citrus essential oils. All of the citrus essential oils used in this study mainly consisted of hydrocarbons.