Gas Chromatographic Measurement of Cocaine in Serum, Plasma and Whole Blood

Abstract

A gas chromatographic method is presented to measure cocaine in serum, plasma or blood. To reduce the in-vitro chemical and enzymic hydrolysis of cocaine, samples should be collected into fluoride oxalate tubes, frozen immediately and stored at — 20°C until analysis. Extractions are carried out in disposable glass tubes immersed in an ice-bath. The method uses a single step extraction from a mildly basic solution into n-butyl acetate containing maprotiline internal standard. A portion of the upper organic layer is chromatographed for 5 min isothermally on a packed column (3% SP2250) with nitrogen-phosphorus detection. The coefficient of variation (CV) of the assay is below 6% at 0·1 mg/L and the limit of accurate measurement is 0·02 mg/L. A case of acute cocaine intoxication is described to illustrate the application of the method.