Comparison of two chromatographic methods for the determination of cocaine and its metabolites in blood and urine

After a solid-phase extraction, two chromatographic procedures (GC/FID and HPLC/UV detector) for the determination of cocaine and its metabolites (benzoylecgonine and ecgonine methyl ester) in human blood and urine have been developed. Linear calibration curves were obtained in urine over the concentration ranges of 0.16-4 mug/mL and 0.2-4 mug/mL, by GC and HPLC, respectively; and, in blood, between 0.1 and 2 mug/mL, by both methods. The recoveries ranged from 66% to 83% for GC, and from 61% to 95% for HPLC. The limit of detection was found to be below 76ng/mL for all the analytes. Precision and accuracy were studied with acceptable results. The methods have been applied simultaneously to quantitate the compounds in real samples; concentrations of cocaine and benzoylecgonine determined by GC/FID correlated well with those determined by HPLC/UV in most cases.