A portable electrochemical method for cocaine quantification and rapid screening of common adulterants in seized samples

[Display omitted] •The electrochemical oxidation of cocaine in acid media is proposed for the first time.•Excellent selectivity for cocaine quantification.•Two methods for fast screening of common adulterants in cocaine seized samples.•Minimal sample manipulation (dissolution in electrolyte). A simple and robust batch-injection analysis system with square-wave voltammetric (BIA-SWV) detection is proposed for the determination of cocaine and screening of the most common adulterants (benzocaine, caffeine, lidocaine, phenacetin, paracetamol, and procaine) in seized cocaine samples. The sample only requires a dissolution step in electrolyte (0.1molL−1H2SO4) prior injection into the BIA cell. SWV scanning is performed after injection of the sample plug and cocaine and adulterants are electrochemically oxidized on a boron-doped diamond electrode (BDDE), resulting in a unique voltammetric profile. The use of BDDE was essential to achieve, for the first time, the electrochemical oxidation of cocaine in an acid medium. Using the optimized experimental conditions, a linear response was found for cocaine concentrations ranging from 6 to 30mgL−1, with a detection limit of 0.27mgL−1 (0.89μmolL−1). The accuracy of the proposed method was estimated by comparing the results obtained for seized cocaine samples by GC-FID and with the addition and recovery protocol. Furthermore, BIA with multiple pulse amperometric (MPA) detection is also proposed as a promising protocol for faster screening of seized cocaine samples.