Desenvolvimento de método para determinação de resíduos de tiametoxam em grãos de feijão, empregando extração sólido-líquido com partição à baixa temperatura

Abstract

The application of pesticides has been evidenced since the beginning of large crops to combat pests and, therefore, contain harmful diseases to plantations. However, the use of these substances requires monitoring, especially in recent decades, when their use is considered exacerbated and carried out on a large scale. Considering the risks of contamination of environmental compartments, such as soil and water, and non-target organisms, from the consumption of food contaminated with pesticide residues, in this work, we developed a method for the determination of thiamethoxam in bean grains using solid-liquid extraction with a low-temperature partition (SLE-LTP). For the separation and quantification of the insecticide, high-performance liquid chromatography with detection by a diode array was used. The SLE-LTP method has advantages, such as the significant reduction in sample amounts and organic solvents, accessibility and simplicity, low cost, low analyst interference, and high efficiency for complex matrices. Initially, we optimized some SLE-LTP parameters, such as the type of extractor solvent, sample mass, extractor volume, the mass of KCl, and freezing time. The solvent that presented the best percentages of recovery was ethyl acetate, in the proportion of water: extractor of 2.0:4.0 (v/v), mainly after the addition of 40 % (m/v) of KCl, using a mass of 500 mg of beans and freezing for two hours, resulting in extraction rates close to 100 %. Following the optimization of the extraction method, the method validation was carried out based on the parameters proposed by the European Community validation guide, document SANTE/11312/2021. Thus, the proposed method was able to extract, separate and quantify thiamethoxam residues in a complex sample, such as bean grains, with LOQ of 0.08 mg/ kg, demonstrating good detectability of the method, below the maximum residue limit for thiamethoxam in bean grains.