Sensor eletroquímico à base de biocarvão de semente de uva para determinação de fenamifós em diversas amostras

Abstract

The increase in the use of pesticides is due to the high demand in food production, aiming to improve the quality and quantity of agricultural products. However, the abusive application of these highly toxic compounds can cause serious problems for the environment and humans. Fenamiphos is a nematicide, classified as toxicological level I, and exhibits a significant residual effect. In this context, this work proposes the development of an electroanalytical methodology for the determination of fenamiphos (FNP), using a carbon paste electrode (CPE) modified with biochar produced from residual grape seed biomass. The biochar was characterized by techniques such as FT-IR, CHN, SEM, and nitrogen adsorption and desorption, indicating that the carbonaceous material exhibits microporosity, high surface area, and contains functional groups dispersed in its structure, favoring interaction with organic compounds, such as the studied pesticide. The electrode modification led to an approximately 36% increase in current intensity compared to the unmodified electrode. Optimizations in the medium parameters (supporting electrolyte, pH, pre-concentration time, and modifier content) and technique (pulse amplitude and time, and scan rate) were carried out to improve analyte detection and electrode sensitivity. Under the optimized analysis conditions, there was an approximately 6-fold increase in the electrochemical signal of FNP compared to the initial conditions used to assess the potential of the CPE modified with grape seed biochar (bSU). The proposed methodology showed an extensive linear working range between 0.005 and 1.100 μmol L-1 , achieving excellent detection and quantification limits of 0.3 and 0.9 nmol L-1 , respectively. Furthermore, it exhibited relative standard deviations below 5% for repeatability and reproducibility tests, respectively, and showed high sensitivity to the presence of concomitant species and recoveries above 90%, highlighting the high potential of the proposed methodology and electrode for the detection of the studied analyte.