Chemical characterisation of the different types of volatile oil constituents by various solute retention ratios with the use of conventional and novel commercial gas chromatographic stationary phases.

Retention ratios of an unknown solute peak from a volatile oil can help to identify its chemical type. Relative retentions on conventional stationary phases can be used to calculate a polar/non-polar ratio which may suggest it is an aromatic solute or a sesquiterpene hydrocarbon. With dipentyl (DA) cyclodextrin phases, gamma-DA/alpha-DA ratios can indicate a bicyclic or monocyclic monoterpenoid. Temperature change on alpha-DA can pick out a non-alcoholic saturated cyclic monoterpenoid, using 150/125 degrees C. Twenty retention ratios are reviewed involving various phases, including other modified cyclodextrins, liquid crystals, "Chirasil-Val" and crown ethers. Applications to six volatile oils are made using a variety of phases.