Estudos para determinação de 4-aminofenazona em amostras de cocaína usando eletrodo de carbono vítreo modificado com nanocompósito de óxido de grafeno reduzido e azul da Prússia

Abstract

In this work we show the electrochemical preparation of a nanocomposite film of reduced graphene oxide and Prussian blue (rGO/FeHCF) and its subsequent application as an electrochemical sensor in the detection of 4-aminophenazone (4AF) in seized cocaine samples. The material was produced on a glassy carbon electrode in a typical three-electrode electrochemical system by cyclic voltammetry (CV) immersed in a GO dispersion with Fe2+ ions. After drying, this precursor was subjected to successive cyclic voltammograms in potassium ferricyanide solution, obtaining the desired rGO/FeHCF nanocomposite. The electrochemical tests after film formation demonstrated a synergistic effect between the materials that could be evidenced by the increase in current intensity and by the good chemical stability during 50 CVs in acid medium (pH = 4). The characterizations carried out by means of Raman spectroscopy and infrared absorption with Fourier transform showed effective reduction of GO as well as the formation of the PB film. The microscopy images showed PB particles well distributed on rGO sheets and their constitution was also confirmed by EDX. In CV studies, investigations were carried out to identify the region where the analyte showed redox activity using the modified and unmodified glassy carbon electrode. Studies carried out by batch injection analysis with amperometric detection demonstrated that the determination of 4AF was possible in cocaine samples (without interference from the common adulterants present in this type of sample). In addition, a comparison was also performed using the unmodified GC electrode for the determination of 4AF. It was noticed that the GC electrode showed better sensitivity for the determination of 4AF, demonstrating that the clean electrode is also a good alternative to the determination of this analyte in forensic samples.