Validation of a method using solid phase extraction and liquid chromatography for the determination of pesticide residues in groundwaters

a method is described for the determination of the pesticides carbofuran, clomazone, 2,4-d and tebuconazole in groundwaters. the method involves solid phase extraction (spe) with c18 cartridges and quantification by high performance liquid chromatography with diode array detector (hplc-dad). after the optimization of the extraction and separation parameters, the method was validated by evaluating the analytical curve, linearity, limits of detection and quantification, precision and accuracy (recovery). the method presents an average recovery of 87.9% and 96.9%, in repeatability and intermediate precision conditions, respectively, with adequate precision (rsd from 0.8 to 20.7%), for all compounds. the method will be applied to determine pesticides in groundwater samples with limit of quantification of 0.2 μg l-1.