Determinação Rápida E Simples De Citrato De Sildenafila (Viagra® E Genéricos) Empregando Eletrodo Impresso De Carbono Em Sistemas Fia E Bia Com Detecção Amperométrica

Abstract

This work presents two amperometric methods for Sildenafil Citrate (SC) determination in erectile dysfunction drugs (Viagra® and Generics), using Batch Injection Analysis (BIA) and Flow Injection Analysis (FIA) systems with a cell for Screen Printed Electrodes (SPE). In Britton-Robinson buffer solution (pH 2), the SC presented an irreversible anodic peak at around +1.0 V vs. Ag pseudo-reference electrode, using five different working electrodes of commercial SPE. The carbon SPE (unmodified) was selected as the best working electrode, providing good sensitivity, precision and low-cost. The SC amperometric detection for two proposed methods was performed at +1.1 V. The best conditions for SC determination by hydrodynamic systems were obtained through injection volumes of 50 and 150 μL at flow rates of 100 and 75 μL s-1, for BIA and FIA respectively. In these conditions, BIA system showed the best sensitivity (0.188 μA mol-1 L) and theoretical analytical frequency (360 h-1) for SC determination. The repeatability studies were similar for both systems with relative standard deviation of approximately 3.0%. The SC analyses in pharmaceutical samples obtained by two proposed methods were compared to HPLC-UV method.