Strategies to avoid electrode fouling for nimesulide detection using unmodified electrodes

Voltammetric quantification of nimesulide presents a serious drawback due to surface fouling on unmodified electrodes. In the anodic region, the electrode fouling effects are critical and alternative procedures are required to bypass this effect. In the present study, new strategies for nimesulide quantification in pharmaceutical agents in the anodic region were developed. We propose a simple procedure to overcome this problem: just doing an electrochemical conditioning process before measurement. This was achieved by differential pulse voltammetry (DPV) and multiple pulsed amperometry (MPA), using batch and in flow injection analyses, respectively. These studies were performed in the presence of 0.1 mol L-1 H2SO4 and the application of 1.6 V to the electrode surface at short time intervals was effective both for electrode surface cleaning and for attaining a steady state regime. The new procedures proposed here allow for quantification of nimesulide in both anodic and cathodic regions, favouring the quantification of this species in complex samples. The results obtained here were in good agreement with the official spectrophotometric method recommended in the Brazilian Pharmacopoeia.