Optimization and Validation of the Preconcentration Technique with SBSE Coupled HPLC-UV/DAD for the Identification of Atrazine and Two of its Metabolites, 2-Hydroxyatrazine (2-HA) and Desethylatrazine (DEA) in Aqueous Samples

The purpose of this work is to address an environmental problem in Mexico, which uses significant amounts of water for agricultural activities, where atrazine is frequently used as a pesticide for weed control. Currently, there is no law prohibiting its use, even though it is considered an endocrine disruptor in some mammals and harmful to health. Due to the difficulty in the direct quantification of several herbicides, which present a low concentration in water, the present work aims to develop the optimization and validation of the preconcentration with magnetic stir bars (SBSE) in aqueous samples for the quantification of atrazine and two of its metabolites: 2-hydroxyatrazine (2-HA) and desethylatrazine (DEA), coupled to High-Performance Liquid Chromatography (HPLC-UV/DAD). For the optimization of the preconcentration technique, the nature and quantity of the solvents used in each step, contact time for retention and quantitative extraction of the analyte, as well as the effect of the concentration of the analyte on its retention on the bar were considered. Finally, it was determined that the presence of the metabolites 2-HA and DEA does not affect the sorption of atrazine on the sorption bar used. The analytical methodology can be considered as an efficient method of atrazine preconcentration for subsequent quantification via HPLC-UV/DAD in the range of 0.03 to 0.25 mg/L and in the absence of matrix interferences; its limits of detection and quantification are respectively 0.0014 mg/L and 0.0016 mg/L.