Análise multirresíduo de inseticidas em batata (Solanum tuberosum L.) / Analysis multiresidue of insecticides in potato (Solanum tuberosum L.)

AUTOR(ES)
DATA DE PUBLICAÇÃO

2007

RESUMO

The objective of this project was to develop and valid the solid-liquid extraction methodology and purification in low temperature (ESL-PBT) to the residues analysis of the insecticides, chlorpyrifos, λ-cyhalothrin, cypermethrin and deltamethrin in potatoes. On the optimization stage, the agrotoxics extraction of interests of samples of fortified potatoes was made with extractor mixtures (water, acetonitrile and ethyl acetate) determined through an experimental planning, obtaining as answer the efficiency on the insecticides extraction. The potato samples with the extractors mixtures, in unique phase, were shaken and put in a freezer for approximately 12 hours. After being separated in phases by the freezing of the watery phase, with the temperature reduction, the superior phase, still liquid, was separated and submitted to an analysis for gaseous chromatography using detector for electrons capture and biphenthrin as internal standard. On the method optimization stage, some variables were evaluated on the potato agrotoxics extraction process such as: ionic force, the usage of ultrasound, type of freezing, extractor mixture containing methanol, time extraction and fortification. The optimized method consists in adding in 3,000 g of triturated potato, 1,0 mL of water, 6,5 mL of acetonitrile, 2,5 mL of ethyl acetate and submit the mixture to the sonication for 10 minutes followed by freezing. The liquid organic phase on the supernatant passed through a paper of filter with sodium sulphate anhydrous. The optimized method was validated determining the selectivity, tax of linearity, limits detection and quantification, precision and accuracy. The obtained results showed that the developed method constituted of ESL-PBT followed by chromatographic analysis is efficient to the insecticide residues analysis normally applied in potatoes, showing recuperation percentages higher than 80% and detection limits under the maximum limits of residues (LMR) established for these agrotoxics on this type of food. Besides, the methodology presents a small consume of solvents (10,0 mL) and lack of purification stages of the extracts before the chromatographic analysis. The matrix effect showed itself present on the quantification of the agrotoxics for gaseous chromatography. To get over this effect, analytic curves were prepared in organic extracts, obtained through the extraction of non-contaminated potatoes. In these conditions were obtained recuperation percentages over 70 % to all the insecticides. This matrix effect gets smaller, significantly, during the extracts storage process, although the low temperature. The optimized and validated method was applied in potatoes samples obtained from potato creators from the South Region in the state of Minas Gerais and in Viçosas - MG market. It was detected the presence of chlorpyrifos residues under the established LMR in cultivated potatoes on the conventional way. It was observed that the residues retention occurs on the potatos rind and its not eliminated even after their cooking.

ASSUNTO(S)

quimica analitica análise de resíduos batata potato residue analysis gaseous chromatography cromatografia gasosa

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