Desenvolvimento de sensor eletroquímico à base de ferroceno carboxílico para detecção de HPA’s em derivados de cana-de-açúcar

Abstract

Aromatic Polycyclic Hydrocarbons (HPA's) are volatile organic compounds from the incomplete combustion of organic matter and comprise an important class of environmental contaminants, many of which are proven to be carcinogenic. In the present study, samples of sugarcane derivatives as well as 5 HPA's were analyzed, being anthracene, benzo (a) pyrene, benzo (b) fluoranthene, phenanthrene and naphthalene, which were chosen due to their high carcinogenicity. In order to prepare a gold electrode modified with ferrocene carboxylic acid, to analyze the electrochemical behavior of the substances of interest and to develop na electrochemical sensor for analysis of HPA's, studies were carried out using a glassy carbon electrode and gold modified with carboxylic ferrocene. Experiments with Fourier Transform Infrared Spectroscopy (FTIR) and Cyclic Voltammetry were developed to prove that the process of modification of the gold electrode was effective, that is, the reaction of the free amino group with the carboxylic group, forming the amide group. The methodology was applied in the sense of performing Cyclic Voltammetry and Differential Pulse Voltammetry, Proton Magnetic Resonance (NMR1H) and High Efficiency Liquid Chromatography (HPLC) with fluorescence detector. The results obtained evidenced that the HPA's standards are not electroactive at pH 7. A new sensor was prepared and characterized, this one formed from gold modified with ferrocene carboxylic, in which a catalytic response was presented for all HPA's studied. With this sensor it was possible to construct calibration curves as well as to analyze the presence of the anthracene, benzo (b) fluorethane, phenentrene and naphthalene HPAs in real samples, being demerara sugar, brown sugar, plantain honey and rapadura. The analysis of 1 H NMR showed no evidence of the presence of HPA's in the samples studied. Analysis with High Performance Liquid Chromatography it was possible to validate the presence of PAHs. This project demonstrated the practicality and efficiency of the electrochemical sensor for the analysis of HPA's tested.