Application of comprehensive two-dimensional gas chromatography (GC × GC) to the enantioselective analysis of essential oils

A new method for the enantioselective analysis of essential oils is described, using comprehensive two-dimensional gas chromatography (GC × GC). The column set comprised a primary column containing a cyclodextrin derivative as a chiral selector, and a secondary column containing a polyethylene glycol stationary phase. A cryogenic modulation system was used to achieve the GC × GC experiment. The enantiomeric compositions of a number of monoterpene hydrocarbons and oxygenated monoterpenes in Australian tea tree (Melaleuca alternifolia), including α-thujene, sabinene, β-pinene, α-phellandrene, limonene, trans-sabinene hydrate, cis-sabinene hydrate, linalool, terpinen-4-ol, and α-terpineol are reported. The GC × GC resolution advantage is shown to improve the efficiency of enantioselective essential oil analyses. In a single temperature programmed analysis, the individual antipodes of optically active components can be separated, and are effectively free from matrix interferences.