Validação de método de extração e análise multirresíduo de agrotóxicos em carne bovina por cromatografia gasosa

• Ano de defesa: 2008
• Autor(a) principal: Silva, Érica Pacheco
• Orientador(a): Queiroz, Maria Eliana Lopes Ribeiro de
• Banca de defesa: Afonso, Robson José Cássia Franco , Mendonça, Regina Célia Santos
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de Viçosa
• Programa de Pós-Graduação: Mestrado em Agroquímica
• Departamento: Agroquímica analítica; Agroquímica inorgânica e Físico-química; Agroquímica orgânica
• País: BR
• Palavras-chave em Português: Análise de resíduos; Agrotóxicos; Carne bovina; Cromatografia gasosa
• Palavras-chave em Inglês: Residue analysis; Pesticides; Beef; Gas chomatography
• Área do conhecimento CNPq: CNPQ::CIENCIAS EXATAS E DA TERRA::QUIMICA::QUIMICA ANALITICA
• Link de acesso: http://locus.ufv.br/handle/123456789/2069

The objective of this study was to optimize and validate the liquid-solid extraction with low-temperature purification (LSE- LTP) method for the analysis of chlorpyrifos, endosulfan, cypermethrin and deltamethrin pesticides residues in beef samples. Ideal conditions for the extraction of the pesticides of interest from the rump and liver cattle samples were determined by the employment of experimental planning to optimize the process. Sample mass, solvent extractor, ionic force, extraction time and agitation form were all evaluated. Rump and liver cattle samples were agitated with one-phase solvent mixtures and placed in a freezer for approximately 12 hours. The solids matrix and frozen aqueous phase were separated from the superior liquid phase. This superior phase was filtered and submitted to chromatography analysis using bifenthrin as an internal standard. The optimal technique consisted of supplementing 3.0000 g of beef with 1.0 mL of water, 6.5 mL of acetonitrile, 1.5 mL of ethyl acetate for the rump samples or 1.0 mL of water and 8.0 mL of acetonitrile for the liver samples, and submitting this mixture to ultrasound agitation for 10 minutes, followed by freezing. After separating the phases by freezing the aqueous phase, the supernatant liquid (10 mL) was removed and analyzed by gas chromatography with an electron capture detector. The clean up stage was evaluated for the liver extracts, however, during this stage, not only was the analysis time and cost increased, the percentage of analyte recovery diminished. With the intention of comparing the LSE-LTP with other techniques, the rump and liver samples were submitted to matrix solid phase dispersion (MSPD) extraction. However, this methodology presented recoveries inferior to those of the LSE-LTP in rump samples. For the liver samples, the MSPD technique showed to be little selective, presenting extracts less pure than those obtained by LSE-LTP, due to the greater extraction of matrix components. The optimized method was validated according to selectivity, linearity, detection limits and quantification of the method, precision and accuracy. The results showed that optimized LSE-LTP is efficient for the analysis of the pesticide residues of interest in rump and liver cattle with recovery percentages greater than 70 % and detection limits below the maximum residue limits (MRL) established by Codex Alimentarius the for these pesticides in the studied beef samples. This methodology also presents the small consumption of solvent and absence of purification steps of extracts before chromatography analysis. The effect of the matrix was found to be present in the quantification of pesticides by gas chromatography. To overcome these effects, calibration curves were prepared from organic extracts, obtained from rump and liver cattle free of contaminants. The optimized and validated technique was applied in beef samples acquired commercially in the city of Viçosa, Minas Gerais, Brazil. No trace of chlorpyrifos, endosulfan, cypermethrin or deltamethrin residues were found in either rump or liver samples.