Optimisation of accelerated solvent extraction of cocaine and benzoylecgonine from coca leaves

Abstract

Accelerated solvent extraction (ASE) was developed for the rapid extraction of cocaine and benzoylecgonine from coca leaves. Several parameters such as the nature of the extracting solvent, the pressure, temperature, extraction time, addition of alkaline substances, and sample granulometry were investigated to find the best extraction conditions. A central composite design was used to optimise critical parameters (pressure, temperature, and extraction time) and to assess the robustness of the extraction method. It was demonstrated that the extraction method was perfectly robust around optimal conditions (20 MPa, 80°C, and 10 min). Determination of both cocaine and benzoylecgonine in coca leaves was carried out by means of gas chromatography with flame ionisation detection (GC-FID) or capillary electrophoresis with UV detection (CE-UV). With the latter, separation of both compounds was achieved in less than 4 min with the use of a short-end injection procedure.