Avaliação da técnica de extração com partição em baixa temperatura na análise de carbamatos em alimentos e bebidas

• Ano de defesa: 2010
• Autor(a) principal: Goulart, Simone Machado
• Orientador(a): Queiroz, Maria Eliana Lopes Ribeiro de
• Banca de defesa: Paula, Washington Xavier de , Egreja Filho, Fernando Barboza
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de Viçosa
• Programa de Pós-Graduação: Doutorado em Agroquímica
• Departamento: Agroquímica analítica; Agroquímica inorgânica e Físico-química; Agroquímica orgânica
• País: BR
• Palavras-chave em Português: Carbamatos; Aldicarb; Carbofuran; Carbaryl; Cromatografia líquida de alta eficiência
• Palavras-chave em Inglês: Carbamates; Aldicarb; Carbofuran; Carbaryl; High efficiency liquid chromatography
• Área do conhecimento CNPq: CNPQ::CIENCIAS EXATAS E DA TERRA::QUIMICA::QUIMICA ANALITICA
• Link de acesso: http://locus.ufv.br/handle/123456789/210

The carbamate pesticides are used in crops of coffee, citrus and potato, commonly encountered in dark colored foods and beverages in cases of accidental or intentional poisoning in criminal investigations. Optimization studies, validation, stability and matrix effect in the analysis of carbamates by partition extraction technique with low temperature mineral water, chocolate milk, grape juice, cake and Brigadier were conducted in this work. The organic extracts were analyzed by high performance liquid chromatography with ultraviolet detector (HPLC-UV). Preliminary tests were conducted to optimize the method for evaluation of variables in the extraction of pesticides such as organic solvent, volume and mass of sample and organic solvent, ionic strength, method of mixing and stirring times of fortification and partition. For the matrices water, chocolate and grape juice, 2.00 mL sample were placed in contact with 4.00 mL of acetonitrile. For water and grape juice ionic strength (1.5% NaCl) increased the percentages of extraction. After shaking, the sample was placed in the freezer for 3 hours for phase separation and subsequent analysis of the organic fraction by HPLC-UV. The percentages of extraction of carbamate were above 90%. In the extraction of carbamates in the cake and the main difference Brigadier extraction, compared to other mothers, was the need to add water (2.00 mL) in the matrix before extraction with organic solvent (4.00 mL). The proposed method enabled the quantification of residues of aldicarb, carbofuran and carbaryl in samples of different kinds of cakes and Brig. The recovery percentages were above 83%. The optimum method for each array was validated by determining the main figures of merit such as selectivity, limits of detection and quantitation, precision, accuracy and linearity. Even using small volumes of sample and solvent, and not requiring the later stages of clean-up, the extraction technique was selective. Mineral water for the detection and quantification limits were between 5.0 and 10.0 mg L-1 and 17.0 and 33.0 mg L-1, respectively. For chocolate milk, grape juice, cake and brigadier, limits dectecção and quantification were between 8.0 and 15.0 mg L-1 and 25.0 and 50.0 mg L-1, respectively. The factors evaluated in the stability of these carbamates are the storage temperature, ionic strength and light. In addition, we evaluated the stability of the compounds in mineral water at differentpH values for a period of twenty-eight days. The results showed that light, pH and temperature affect the stability of the carbamate and the ionic strength does not affect this stability. In alkaline conditions these compounds are more unstable than in acid medium. Therefore, water samples contaminated with carbamates should be stored until the time of analysis in a freezer, under light and pH around 4. For samples of chocolate and grape juice, light,temperature and matrix composition affect the stability of carbamates. The best way to store the samples until their analysis isin a freezer and protected from light. In the solid matrix of cake and Brigadier stability of the compounds was not significantly affected by any factor evaluated. We also evaluated the effect of matrix components in the quantification of active compounds by HPLC and the results indicated that in all samples alimetos drinks and the matrix effect was made related to the systematic error constant. However, for larger confiabiliade results, techniques ELL-PBT andESL-PBT for the analysis of carbamates in food matrices and beverages by HPLC-UV, we recommend the use of standard curves prepared in extracts from pesticide-free matrix (white matrix). Finally, the partition extraction with a low temperature for the determination of pesticide residues in samples of foods and beverages by HPLC-UV resulted in a simple, effective, with a small sample and solvent consumption, high sampling rate and low cost.