Desenvolvimento de uma metodologia eletroanalítica para detectar e quantificar ocratoxina A em amostras de café
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Data
2025-06-05
Autores
Medeiros, Jane Schneider de
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Universidade Federal do Espírito Santo
Resumo
Ochratoxin A (OTA) is a mycotoxin produced by fungi of the genera Aspergillus and Penicillium, frequently found in food products such as coffee, cereals, and spices. Given its toxicity and potential carcinogenicity, this study developed a sensitive and selective electroanalytical methodology for the detection and quantification of OTA in roasted and ground coffee. The method employed screen-printed electrodes composed of carbon black and graphite (SPE CB-G), modified in situ with cetyltrimethylammonium bromide (CTAB). The technique used was adsorptive stripping differential pulse voltammetry (DPAdSV), optimized through a central composite design (CCD). Raman spectroscopy characterization of the SPE CB-G confirmed the presence of graphite and carbon black, with a conductive surface suitable for electrochemical detection. The electroanalytical response of OTA was investigated using cyclic voltammetry (CV) under different electrolytes and pH ranges, demonstrating an irreversible oxidation process, with the anodic peak potential (Epa) shifting toward less positive values as the pH increased. The optimal electrochemical condition was achieved using phosphate buffer (PB) 0.2 mol L−1 (pH 7.0) with CTAB (80 µmol L−1), which favored OTA adsorption onto the electrode surface through electrostatic interactions with its anionic forms. Epulse, tpulse, tdep, and CTAB concentration parameters in both differential pulse voltammetry (DPV) and DPAdSV techniques were optimized via CCD to maximize the peak current (Ip). The optimized conditions provided excellent sensitivity and selectivity. The calibration curve in PB with CTAB showed linearity in the range of 10.10 to 242.29 ng mL−1 (R2 = 0.994), with a limit of detection (LOD) of 1.39 ng mL−1 and a limit of quantification (LOQ) of 4.20 ng mL−1. In the coffee matrix, LOD and LOQ were 2.70 ng mL−1 and 8.20 ng mL−1, respectively, also with R2 = 0.994. Recovery assays yielded values ranging from 94% to 110% in buffer with CTAB, wheat, and coffee, validating the method even in complex matrices. The analysis of typical coffee interferents revealed variations in OTA Ip due to competition for active sites on the SPE CB-G surface, with CTAB playing a critical role in minimizing these effects. The proposed methodology demonstrated high analytical performance, low cost, and suitability for routine analysis, meeting regulatory limits established by Anvisa and the European Union.
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Voltametria (DPAdSV). , Eletrodo impresso (SPE) , Segurança alimentar