Uso do método QuEChERS (versão cen) modificado na determinação de resíduos de pesticidas em tomate (Solanum lycopersicum L.) por cromatografia líquida/espectrometria de massas

• Ano de defesa: 2021
• Autor(a) principal: Santos, Álvaro Vieira dos
• Orientador(a): Navickiene, Sandro
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Programa de Pós-Graduação: Pós-Graduação em Química
• Palavras-chave em Português: Química; Tomate; Pesticidas; Solanum lycopersicum L. Tomate; QuEChERS; LC-MS
• Palavras-chave em Inglês: Solanum lycopersicum L. tomate; Pesticide
• Área do conhecimento CNPq: CIENCIAS EXATAS E DA TERRA::QUIMICA
• Link de acesso: https://ri.ufs.br/jspui/handle/riufs/14970

Tomato (Solanum lycopersicum L.) is a vegetable classified as vegetable-fruit, which is highly susceptible to the attack of pests. Ergo, formulations of pesticides are applied to control pests that can cause harm to the crop. Therefore, this work aims to develop a method of extraction through QuEChERS for pest residue determination in tomatoes and the analysis through the technique of liquid chromatography-tandem mass spectrometry. Optimizations of instrumental conditions and of the extraction procedure were carried out to analyze 18 pesticides, namely esfenvalerate, abamectin, lufenuron, methomyl, pyraclostrobin, teflubenzuron, thiacloprid, thiophanate-methyl, carbaryl, dimethoate, pirimicarb, malathion, flutriafol, bromuconazole, deltamethrin, azoxystrobin, and thiamethoxam. The analytes were studied through reversed-phase chromatbography, using a stationary phase C18 and mobile phase composed by MeOH:Water with 5 mM of ammonium formate. The set of analyses showed better response using electrospray ionization. In the QuEChERS procedure, different amounts of salts were tested, and the amount of 1.62 g presented more consistent results with mean recovery values of 87±14% with analyts at the concentration of 0.3 μg mL-1 . After that, possible adsorbents for clean-up were evaluated using C18, Florisil, Alumina Neutra, Biochar, Activated Carbon and Silica, in which Florisil showed better performance. We also evaluated the amount of adsorbents present in the dSPE stage, using 450 mg Biochar with C18, C18, Florisil, Alumina and Silica. Florisil also stood out with better recovery intervals between 70%-120%. Aiming at a lower expenditure of reagents maintaining a good efficiency, it was verified the performance between two amounts of adsorbents: 150 mg and 450 mg of Florisil. It was perceived that the method remains effective even using a smaller amount of adsorbent. The pertinence of the clean-up was also evaluated and thus apply a dilution process after extraction. However, dilution proved to be ineffective and with strong matrix effect. The method was valid and applied in tomato samples sold in São Cristóvão/SE, which did not present pesticide residues.