Interference modelling, experimental design and pre-concentration steps in validation of the Fentons reagent for pesticides determination

The determination of atrazine in real samples (commercial pesticide preparations and water matrices) shows how the Fentonʹs reagent can be used with analytical purposes when kinetic methodology and multivariate calibration methods are applied. Also, binary mixtures of atrazine–alachlor and atrazine–bentazone in pesticide preparations have been resolved. The work shows the way in which interferences and the matrix effect can be modelled. Experimental design has been used to optimize experimental conditions, including the effect of solvent (methanol) used for extraction of atrazine from the sample. The determination of pesticides in commercial preparations was accomplished without any pre-treatment of sample apart from evaporation of solvent; the calibration model was developed for concentration ranges between 0.46 and 11.6 × 10^-5 mol L^-1 with mean relative errors under 4%. Solid-phase extraction is used for pre-concentration of atrazine in water samples through C18 disks, and the concentration range for determination was established between 4 and 115 (mu)g L^-1approximately. Satisfactory results for recuperation of atrazine were always obtained.