Thin-layer chromatographic detection of cocaethylene in human urine

A thin-layer chromatographic method was developed for the detection of cocaethylene and cocaine in human urine. Following a standard solid-phase extraction of urine buffered to pH 9.3, the concentrated extract was chromatographed in a solvent consisting of hexane:toluene:diethylamine (65:20:5 mL). Both cocaethylene and cocaine were visualized with iodoplatinate spray. Exclusive of the type of extraction used, the detection limit itself was 16 nmol (5 micrograms) for either compound. The method was applied to urine samples of 13 patients who had ingested cocaine with ethanol. Statistically significant correlations were noted between the intensity of the urine thin-layer chromatographic detection and the measured urine concentrations of cocaethylene and cocaine. The plasma and urine concentrations of both drugs also showed statistically significant correlations. Incorporation of the proposed procedure into commonly used clinical laboratory methodology is described.