Application of factorial design and Box-Behnken matrix in the optimisation of a microwave-assisted extraction of essential oils from Salvia mirzayanii

Essential oil of Salvia mirzayanii cultivated in Iran was obtained by microwave assisted extraction (MAE) procedures. The essential oil was analysed by capillary gas chromatography using flame ionisation and mass spectrometric detections. The effects of different parameters, such as microwave power, temperature, time and type of solvent on the MAE of Salvia mirzayanii oil were investigated. Results of the two-level fractional factorial design (2(4-1)) based on an analysis of variance demonstrated that only the power, temperature and type of solvent were statistically significant. Optimal conditions for the extraction of essential oils were obtained by using Box-Behnken design. For optimum recovery of essential oil the variables power, temperature and solvent values were 115?W, 50°C and 14?s, respectively. Under the optimised experimental conditions, the extraction yield of microwave assisted extraction was 11.2% (w/w).