Improved GC method for the determination of the active principles of Catha edulis

•GC/MS and GC/FID analysis of Catha edulis vegetable material seized in Italy in 2012.•Optimization and validation of the analytical method.•Determination of cathinone, cathine and phenylpropanolamine.

The GC method previously reported by our research group for the analysis of the active principles of Catha edulis, i.e. cathine, cathinone and phenylpropanolamine, was considerably improved. N-methyl-N-trimethylsilyl-trifluoroacetamide (MSTFA) as derivatizing agent was employed, thus allowing an accurate determination of the analytes and a suitable internal standard for quantitative analyses (nicotinamide) was introduced. Moreover the chromatographic conditions were carefully studied to improve the separation of the alkaloids and sensitivity. To this end different chromatographic capillary columns and temperature gradients were investigated. The optimized GC method was validated and resulted adequate for the application in forensic analysis. Finally on behalf of the Tribunal, C. edulis vegetable material seized by the police in northern Italy was analyzed, the quantity of cathine ranging from 0.095 to 0.29%, the quantity of PPA from 0.010 to 0.21% and the quantity of cathinone from 0.025 to 0.374% of the weight of the vegetable material.