AN AUTOMATED PRECONCENTRATION-DERIVATIZATION SYSTEM FOR THE DETERMINATION OF COCAINE AND ITS METABOLITES IN URINE AND ILLICIT COCAINE SAMPLES BY GAS-CHROMATOGRAPHY MASS-SPECTROMETRY

Although gas chromatography/mass spectrometry (GC/MS) is the most powe rful technique for analysing cocaine and its hydrolysis products (benz oylecgonine, ecgonine methyl ester and ecgonine) in urine, the sample pretreatment required is rather laborious and involves a large number of steps, This paper reports a continuous method for the separation (b ased on the retention properties of cocaine and its major metabolites on a reversed phase C-18 column), preconcentration (evaporation under nitrogen) and derivatization (collecion of the residue in a few microl itres of derivatizing reagent) of cocaine and its metabolites in urine samples for subsequent analysis by GC/MS. Calibration graphs are line ar from 5 to 3000 ng/mL; the detection limits are 1 ng/mL (cocaine and ecgonine methyl ester), 20 ng/mL (benzoylecgonine) and 200 ng/mL (ecg onine), The method was applied to illicit cocaine samples and to urine from a drug addict.