ABSTRACT
The evaluation of a link between two heroin seizures using a descriptive method is presented. It is based on the measure of the angles between two chromatograms assimilated to vectors, and interpreted using a continuous approach based on the likelihood ratio of Bayes' theorem. A complete evaluation model thus avoids the drawbacks of decision thresholds used until now to establish a link. Validation is obtained through tests and simulation methods.
Subject(s)
Forensic Medicine/statistics & numerical data , Heroin/adverse effects , Narcotics/adverse effects , Seizures/chemically induced , Statistics as Topic/methods , Humans , Likelihood Functions , Models, Statistical , Reproducibility of ResultsABSTRACT
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.
Subject(s)
Cocaine , Drug Residues/analysis , Heroin , Solvents/analysis , Chromatography, Gas , Drug ContaminationABSTRACT
A free zone capillary electrophoresis (CZE) system, with diode array detection, was used in the analysis of ephedrine and 9 amphetamines. The method was quantitative, offering better resolution than gas chromatography (GC), without the need for sample derivatisation. Under hydrodynamic injection, the concentrations of drug at which detection limits were reached lay between 13 and 68 micrograms/ml, with detection at 214 nm, these limits being of the same order of magnitude as those of GC. Analysis of casework samples by the two methods demonstrated the advantages of CZE with diode array detection over conventional GC for amphetamine identification and quantification.
