Determinação multiresidual de agrotóxicos em camas biológicas empregando cromatografia gasosa acoplada à espectrometria de massas

Abstract

Pesticides are used worldwide to control pests and diseases in various crops in order to avoid losses, thus increasing production. Considering the toxicity of pesticides, both for the environment and for health, there is a specific law that regulates the production, trade and the transport to the final waste management. In Brazil, there is the Law No. 7802 of July 11, 1989, which has all the necessary specifications to ensure that pesticides are handled properly, from production to final destination of waste and packaging. However, in relation to accidental spills, water discharge from the washing of sprayers, etc., until very recently there was no procedure to avoid this type of contamination. In order to avoid this kind of enviromental contamination, biobeds were created in Sweden. These biological beds were being adapted in several other countries, among them Brazil. Since it is necessary a method to evaluate the efficacy of pesticide degradation of this system, this work aimed the development and validation of a multiresidual method for the determination of pesticide residues in biological beds. The following pesticides were evaluated: captan, being quantified from its degradation product tetrahidroftalimida, chlorpyrifos, chlorothalonil, fenitrothion, methidathion, phosmet and tebuconazole in biological beds using gas chromatography-mass spectrometry. The extraction method used was an adaptation from the of Dutch New mini-Luke method. To study the validation of the method the following criteria were evaluated: precision and accuracy, intermediate precision, limit of detection (LOD) and quantification (LOQ), linearity, linear range, selectivity and matrix effects. As a result there was obtained LOD from the method of 10 μg kg-1 for chlorpyrifos, phosmet and methidathion; as for tetrahidroftalimida (a captan degradation product), tebuconazole and chlorothalonil the detection limit was 20 μg kg-1. The LOQ for all pesticides was 50 μg kg-1.