Supercritical fluid chromatography of sesquiterpene hydrocarbons on silica packed columns with on-line Fourier transform infrared detection

Abstract

The on-line coupling of carbon dioxide supercritical fluid chromatography with Fourier transform infrared (FT-IR) spectrometry allows the separation and identification of sesquiterpene hydrocarbon mixtures on bare silica as stationary phase. Separations of these non-polar but extremely thermosensitive organic compounds required low-temperature rather than low-density experimental conditions. These chromatographic conditions preserved structural information about these sesquiterpene hydrocarbons, such as the differentiation of methyl groups (1375–1385 cm −1) from methylene groups and the geminal or single nature of methyl groups (twin bands near 1360–1390 cm −1 or a single band near 1380 cm −1). The method was applied to the identification of the sesquiterpene hydrocarbon fraction of several essential oils; important structural features provided by their FT-IR spectra are reported.