Fenton’s reagent for kinetic determinations

The use of the Fenton’s reagent (FR) (a mixture of H₂O₂ and Fe²⁺) for the kinetic determination of individual chemical species is proposed. The possibilities of the reagent arise from the oxidant power of intermediate species generated during the slow oxidation of Fe²⁺ by H₂O₂, but very few analytical applications of the reagent can be found. The oxidation of organic compounds (known as the Fenton reaction) is in fact an induced chain reaction that proceeds to an extension which is influenced by the reaction conditions. Experimental design has been used for optimization thinking of the analytical application. The pesticide atrazine has been used as analyte to test the analytical possibilities of the FR. Partial least squares regression (PLS), applied to reaction profiles between 206 and 270 nm, was used as algorithm to make the calibration model. Atrazine concentrations ranging from 0.46 to 13.4×10⁻⁵ M have been used for calibration, and mean errors under 2.5% both for calibration and validation have been found. Other classical methods of calibration such as those using absolute values of absorbance, initial rates, etc. gave poor results in the cases considered. According to the study of interferences, the main drawback of the reagent is the lack of selectivity, but some possible ways of improving it are discussed. The method was applied for the determination of atrazine in several commercial atrazine-based pesticide preparations. In general, good results were obtained when compared with those found by gas-liquid chromatography as a reference. Recovery studies also gave satisfactory results.