A method for the simultaneous determination of cocaine, benzoylecgonine, and ecgonine methyl ester in blood and urine using GC/EIMS with derivatization to produce high mass molecular ions.

A method for the simultaneous analysis of cocaine (COC), derivatized benzoylecgonine (BE), and derivatized ecgonine methyl ester (EME) has been developed. Blood or urine containing deuterated analogs of the three analytes is extracted by pouring over a Chem-Elut column and eluting with chloroform/isopropanol (9:1). The eluent is collected, split into two equal aliquots, and evaporated to dryness. In one aliquot, dimethylformamide and dimethylformamide dipropyl acetal are allowed to react and to derivatize BE to n-propyl COC. In the other aliquot, 4-fluorobenzoyl chloride, pyridine, and benzene are used to derivatize EME to p-fluoro-COC. COC is not affected by these reactions and may be found in either aliquot. Separation was performed on an HP 5890 GC using an HP-1 capillary column. The oven temperature was initially 100 degrees C for 1 minute, then programmed at 30 degrees/minute to a final temperature of 260 degrees C. The GC/MS was operated in the SIM mode, and the masses monitored were 303, 321, and 331 respectively for COC and derivatized EME and BE, and 308, 324, and 334 for the respective deuterated internal standards. The assay showed a minimum linear range of 0.05-2.0 mg/L for COC and 0.10-4.0 mg/L for each of the metabolites.