Desenvolvimento de métodos eletroanalíticos para a determinação do diuron e ametrina e estudos de sorção em solos sob mata e cana-de-açúcar
Soares, Gabriela Byzynski
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It is vital to know the mechanisms and processes of interaction between pesticides and the environment and monitor the groundwater, surface water and soil in intensively used areas which such products for the evaluation of the pollution degree of natural resources. Therefore, there is a need for accurate, reliable and affordable methods of analysis. The objective of this work was to develop electroanalytical procedures for the determination of the herbicides diuron and ametryne, for the study of their sorption in soils under sugar cane production and the native forest in the sub-basin of the Ribeirão das Guabirobas, São Carlos and estimate their potential of contamination of surface and groundwater. The soils studied have contrasting granulometric sizes (sandy and clayed) and were characterized chemically and mineralogically by different techniques. Electroanalytical methods were developed for the determination of diuron with composite GPU electrode and ametryne with silver amalgam electrode. The methodologies developed were used to determine the concentrations of the herbicides in the equilibrium in the batch experiments. The sorption coefficients (Kd) obtained for diuron in the four soils tested showed higher influence with the amount of clay and the amount and quality of soil organic matter in sorption process. For ametryne, there was an important influence of pH in the sorption capacity of the herbicide in the soils. The results are in agreement with the data found in the literature using others techniques, such as chromatography and liquid scintillation, allowing to conclude that the developed procedures using the GPU and silver amalgam electrodes are suitable for the determination of sorption isotherms of these herbicides in soils, having the advantages of being simple and less expensive when compared with the conventional methods.