Gas chromatographic quality control for oil of Melaleuca terpinen-4-ol type (Australian Tea Tree)

Detailed GC and GC-MS analyses of oil of Melaleuca have identified several constituents not previously reported from Melaleuca alternifolia and clarified some earlier assignments. The range, mean, and coefficient of variation for the principle constituents in 800 typical samples are presented along with the compositions of several substandard oils. Isolation and storage procedures affecting the chemical composition of the oil are reported. Ethanolic extraction of mature leaves gave solutions suitable for direct injection into a gas chromatograph for the qualitative determination of tea tree oil. Comparison with conventional steam distillation showed that this technique was suitable for preliminary analysis of tea tree oil yield and quality.