Headspace analysis of solvents in cocaine and heroin samples

Solid phase adsorption of headspace vapours was used to trap occluded solvent residues contained in 41 heroin and 54 cocaine samples, seized in Switzerland between 1994 and 1996, onto activated charcoal. The residues were eluted with carbon disulphide and analysed by GC-FID. Identification was confirmed by GC-MS. The detection limits between 2-15 ppm were determined empirically on a w/w basis for 250-300 mg powder samples. Twelve and 16 solvents were identified in the heroin and cocaine samples respectively. It was possible to relate cocaine samples to each other, but heroin comparisons proved more problematical. Trends and geographic variation in solvent use are considered and recommendations are made with respect to the control of certain solvents frequently encountered in heroin and cocaine samples.