Flow injection analysis with amperometric detection of cocaine in confiscated samples

Flow injection analysis (FIA) with amperometric detection is applied to the determination of cocaine. Flow parameters were optimised prior to electrode calibration: a detection potential of +1 V vs. Ag/AgCl/sat. KCl and a flow rate of 2.5 ml min−1 resulted adequate. A relative standard deviation of 1.7% was calculated for a concentration level of 6.2 × 10−6 (n = 12) without carrying out a carbon paste electrode pretreatment. Calibration curves were found to be linear between 2 × 10−7 and 10−5 M, and the method has a detection limit of 2 × 10−7 M. A simple and reproducible procedure is proposed for the determination of cocaine in illegal dosage forms confiscated by police authorities. The method compared favourably with liquid chromatography with UV detection.