Electrochemical behavior of labetalol at an ionic liquid modified carbon paste electrode and its electrochemical determination

Abstract

Electrochemical behavior of labetalol (LBT) at carbon paste electrode (CPE) and an ionic liquid1-benzyl-3-methylimidazolehexafluorophosphate([BnMIM]PF6)modified carbon paste electrode([BnMIM]PF6/CPE)in Britton-Robinson buffer solution (pH 2.0) was investigated by cyclic voltammetry (CV) and square wave voltammetric (SWV). The experimental results showed that LBT at both the bare CPE and [BnMIM]PF6/CPEshowed an irreversible oxidation process, but at [BnMIM]PF6/CPE its oxidation peak current increased greatly and the oxidation peak potential shifted negatively. The electrode reaction process is a diffusion-controlled process involving one electron transferring accompanied by a participation of one proton at [BnMIM]PF6/CPE. At the same time, the electrochemical kinetic parameters were determined. Under the optimized electrochemical experimental conditions, the oxidation peak currents were proportional to LBT concentration in the range of 7.0 x 10-6-1.0 x 10-4 mol L-1 with the limit of detection(LOD, S/N=3) of 4.810 x 10-8 mol L-1and the limit of quantification(LOQ, S/N=10) of 1.60 x 10-7 mol L-1, respectively. The proposed method was successfully applied in the determination of LBT content in commercial tablet samples.