The application of capillary gas chromatography-electron capture detection in the comparative analyses of illicit cocaine samples.

The gas chromatographic detection of manufacturing impurities in illicit cocaine can be enhanced by chemical derivatization and the use of an electron-capture detector. After derivatization of illicit cocaine hydrochloride samples with heptafluorobutyric anhydride, the isolated heptafluorobutyryl derivatives of the cocaine impurities were subjected to capillary gas chromatography-electron capture detection analysis. The on-column detection of cocaine impurities at low picogram levels was possible for compounds such as N-norcocaine and other N-demethylated impurities, amidic by-products, including N-benzoylnorecgonine methyl ester and tertiary amines possessing hydroxy functions. The latter compounds include the so-called hydroxycocaine impurities, believed to be new coca leaf alkaloids. This methodology is especially suited for sample comparison analyses.