Eletrodo de pasta de carbono quimicamente modificado contendo uma rede polimérica de poli(dimetilsiloxano) funcionalizada com o ligante 2-aminotiazol para a determinação de cobre

Abstract

Through a preparation carried out in two stages, a new material was obtained based on a polymeric network, having as precursors poly(dimethylsiloxane) (PDMS), tetraethylorthosilicate (TEOS), 3-chloropropyltrimethoxysilane (CPTMS) and graphite. According to the PDMS:CPTMS mass ratio, the products of the first stage were named C25, C50 and C90. In the second part of the synthesis, the Cl present in the CPTMS was replaced by the 2-aminothiazole ligand (AMTZ), and these were named A25, A50 and A90. The prepared materials were characterized by Thermogravimetric Analysis (TGA) and Spectroscopy in the infrared region with Fourier transform with attenuated total reflectance accessory (FTIR-ATR). These data confirm the formation of the AMTZ functionalized polymeric network. With these materials, chemically modified carbon paste electrodes (C25, A25, A50 and A90) were constructed. The conductive properties of the electrodes were evaluated by Cyclic Voltammetry using [Fe(CN)6] 3-/4-as a probe molecule. The A25 electrode showed the best voltammetric responses compared to the study with the probe molecule. With these electrodes, Electrochemical Impedance Spectroscopy measurements were performed, showing that A25 has a higher capacitive character and lower total impedance. To study the electrochemical behavior of the electrodes in relation to copper ions, Cyclic Voltammetry and Square Wave Voltammetry were used. The results obtained showed that the A25 electrode has characteristics more suitable to be applied as a sensor for copper, for example, higher values of anodic current density. Using the A25 electrode in Square Wave Voltammetry with anodic stripping, in a concentration range of 2.00 – 19.60 μmol L-1of copper, detection limit and quantification limit of 0.12 and 0.40 μmol L-1 were determined. The application of A25 as an electrochemical sensor for copper was carried out with a commercial cachaça sample, efficiently detecting the analyte. The A25 electrode has the potential to be applied as an electrochemical sensor for the determination of copper ions, both in aqueous and alcoholic environments.