Development and validation of a method for the simultaneous estimation of terpinene-4-ol and 1,8-cineole in Melaleuca alternifolia (Maiden & Betche) Cheel and Rosmarinus officinalis L. oil using HPTLC coupled with a QbD approach

This paper comprehends a Quality by design (QbD) approach for development of a simple and precise HPTLC (High performance thin layer chromatography) method for simultaneous estimation of the phytoconstituents terpinen-4-ol and 1,8-cineole found in Melaleuca alternifolia (tea tree oil) and Rosmarinus officinalis (rosemary oil) respectively. The method was optimized by Design expert software using response surface methodology. The chromatographic condition optimized by using software was, mobile phase as hexane: ethyl acetate: glacial acetic acid in the ratio of 8.5:1.5:0.47 % v/v, stationary phase as TLC plates precoated with silica gel 60 F₂₅₄ at ambient temperature conditions and saturation time 20 min at 366 nm. Optimized conditions were verified and validated as per ICH Q2 (R1) (International council for harmonization of technical requirements of pharmaceuticals for human use) guidelines. The method developed was validated for the parameters such as specificity, linearity, DL, QL, accuracy and precision. This method was then applied for simultaneous estimation of terpinen-4-ol and 1,8-cineole in Melaleuca alternifolia (tea Tree oil) and Rosmarinus officinalis (rosemary oil) respectively.