Determinação e quantificação de cefalexina e cefuroxima em diferentes matrizes utilizando técnicas eletroquímicas.

Abstract

The present work describes the electrochemical behavior of the antibiotic cefuroxime (CFX) and cephalexin (CFA) by cyclic voltammetry (CV) and the development of an electroanalytical methodology for CFX and CFA determination on mercury electrodes allied to the square wave voltammetry (SWV). In this work, CFX showed two irreversible reduction peak at -0.35 V (peak 1) and -1.03 V (peak 2), with the participation of two electrons and two protons for both peaks. It is suggested that the reduction reaction of the CFX occurs on the group – C = N – for the peak one and on the group – CH2 – R for the peak two. Under optimized conditions, the results were obtained in BR buffer pH 2.0, f = 90 s-1, a = 30 mV and ΔEs = 2 mV. Considering the peak 1, analytical curves were constructed and the limits of detection (LOD) and quantitation (LOQ) were calculated with LOD = 4.92×10-9mol L-1and LOQ = 1.64×10-8mol L-1. The recovery in electrolyte was 109.15% with RSD = 2.39% (n = 3). The methodology was applied in raw natural waters, commercial formulations and bovine milk obtaining recovery values from 96.40 to 129.4%. CFA reductions waves are observed at -0.97 V (peak 1) and -1.2 V (peak 2). These reduction waves are attributed to the reduction of ethylenic bond of CFA involving the transfer of two electrons and two protons. The optimized conditions were obtained in BR buffer pH 2.0, f = 100 s-1, a = 30 mV and ΔEs = 4 mV. Considering the peak at -1.2 V, analytical curves were constructed and were calculated with LOD = 1.27×10-8mol L-1and LOQ = 4.23×10-8 mol L-1. The recovery in electrolyte was 89.19% with RSD = 1.51% (n = 3). The methodology was applied to quantify in raw natural waters, commercial formulations and bovine milk obtaining recovery values from 78.45 to 92.13%. In developed methodologies, we obtained low values of LOD and LOQ, recovery between 78.00 to 130.00% and reproducibility below 5.00%, showing that those methods had excellent sensitivity, precision and efficiency.