Development and validation of a multi-residue analytical methodology to determine the presence of selected pesticides in water through liquid chromatography

In the present work an analytical methodology is described to determine the presence of multi-residues of selected pesticides used in sugar-cane cultures ( tebuthiuron, hexazinone, diuron, 2,4-D and ametrine), in source of drinking water. The analytes were isolated from the water matrix through the following techniques: liquid-liquid extraction (LLE) using dichloromethane as solvent; solid phase extraction (SPE) using C-18 as solid support and acetonitrile as solvent to condition the solid phase and elution of the analytes; and supercritical fluid extraction (SFE) using C18 as solid support and CO2 in supercritical state as extractant solvent. The chromatographic analysis was done by high performance liquid chromatography ( HPLC) with an ultraviolet detector and using acetonitrile/ water as mobile phase. Among the three evaluated extraction techniques, the best results were obtained with both liquid-liquid extraction and solid phase extraction.