Abstract
Substantial fraction of herbicides used in the agriculture reaches the soil, an environmental compartment where these substances are liable to processes of adsorption, degradation, leaching, etc. The control of environmental quality requires efficient and low cost analytical methods. After sampling, sample treatment processes including extraction, pre-concentration and elimination of interferences are extremely important, because they influence the quality of the results. The extraction of pesticides from soil samples is still done predominantly in Soxhlet systems, employing time-consuming procedures that consume large volumes of solvent. Strategies for efficient and rapid extraction assisted by ultrasound or microwave have been described, but still using substantial amounts of solvents or expensive instrumentation. An alternative procedure that does not use organic solvents is the cloud point extraction, which has been exploited for extraction, purification and pre-concentration of various pesticides. Currently, great attention has been given to the extraction process called QuEChERS, which aims, as its acronym suggests, be Quick, Easy, Cheap, Effective, Rugged and Safe. In this project we intend to explore cloud point extraction and QuEChERS procedures followed by separation techniques using HPLC (High Performance Liquid Chromatography) and SIC (Sequential Injection Chromatography) with different stationary phases for the determination of the herbicides of the classes of triazines, ureas and uracil in soils and water samples. Among the triazines, emphasis will be given to simazine, ametryne metribuzin, atrazine and metabolites. Among ureas, linuron, tebuthiuron and dinuron will be studied. Bromacil will be selected as representative of the uracil class. The goal of this project is the development of efficient and low cost methods of analysis with minimum waste generation. Extraction procedures based on Soxhlet and ultrasound will be used as a reference methods.
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