GC Method Helps Narrow Source of Drug Distribution

Scientists at the National Police Scientific Institute in Ecully, France have been analyzing solvents trapped within crystals of cocaine hydrochloride with a static headspace-gas chromatography method. This method helps them ascertain the drug's country of origion, which can help determine the distribution chain.

Scientists Laurence Dujourdy and Fabrice Besacier studied the effects of five variables on method performance by measuring the solvent GC peak areas. The overall aim was to compare the trapped solvent profile of a new sample with that in a database, so Dujourdy and Besacier developed a system built using PHP software and a MySQL open source database. A cosine function was employed to compare the unknown to the database and provide a similarity value on a scale of 0-100, where 0 corresponds to a perfect non-match and 100 to a perfect match. A total of 2,863 cocaine samples were analysed over 6 years for the 18 solvents. Of these, 7 appeared in more than 60% of the cases, namely acetone, diethyl ether, isobutanol, propyl acetate, toluene, isopropyl acetate/benzene and hexane/chloroform/ethyl acetate. In the latter two cases, it was not possible to distinguish the respective components.