Simultaneous determination of captopril and hydrochlorothiazide on boron-doped diamond electrode by batch injection analysis with multiple pulse amperometric detection

This work describes a new, simple, and fast electrochemical method for simultaneous determination of captopril (CAP) and hydrochlorothiazide (HCT) using a boron-doped diamond (BDD) electrode associated with batch-injection analysis with multiple-pulse amperometric (BIA-MPA) detection. A sequence of potential pulses was selected in such a way that HCT was selectively detected at +1.4 V/50 ms and both (HCT + CAP), were detected at +1.8 V/50 ms. CAP was quantified without interference of HCT by subtracting the currents detected at +1.8 V and +1.4 V (using a correction factor). The proposed BIA method requires minimal sample manipulation (dissolution and dilution in electrolyte) and the simultaneous determination is achieved with a single injection step of 150 mu L of a sample solution (100 injections h(-1)). The results obtained with the BIA method were compared to those obtained by capillary electrophoresis and similar results were obtained (at 95% of confidence level). A simple and rapid test for detecting the presence or absence of electroactive interferents was also proposed (fast screening test). (C) 2015 Published by Elsevier B.V.