Application of central composite designs in the supercritical fluid extraction of tropane alkaloids in plant extracts

Central composite designs were used in the study of supercritical fluid extraction (SFE) of three tropane alkaloids : hyoscyamine and scopolamine from Datura candida x D. aurea hairy roots and cocaine from coca leaves (Erythroxylum coca). Several SFE parameters, such as pressure, temperature, the nature and percentage of the polar modifier were examined. The tropane alkaloid extraction yield was established as response. A comparison between the predicted and the experimental extraction yields was established in order to assess the prediction quality of the model. Response surfaces were drawn from the mathematical models and enabled to determine the optimal conditions and to visualise the method robustness. The behaviour of the compounds investigated was discussed in relation with the selected SFE parameters.