Application of Gas–Liquid Chromatography to the Analysis of Essential OilsPart XVII.† Fingerprinting of Essential Oils by Temperature-programmed Gas–Liquid Chromatography Using Capillary Columns With Non-polar Stationary Phases
Problems in obtaining reproducible results when ‘fingerprinting’ essential oils by temperature-programmed gas–liquid chromatography have been reported on in Parts VII and VIII of this series. Those reports were concerned with the general problems and the use of packed columns. This report is concerned with the use of capillary columns and non-polar stationary phases. A collaborative study using capillary columns with non-polar stationary phases has resulted in a method which specifies the ‘g-pack value’ of a column and gives reproducible relative retention indices for the test compounds limonene, acetophenone, linalol, naphthalene, linalyl acetate and cinnamyl alcohol. The method has been applied successfully to the examination of oil of rosemary. A recommended method is given for the reproducible temperature-programmed gas–liquid chromatographic fingerprinting of essential oils using capillary columns with non-polar stationary phases.