Kinetic method for the determination of iron(II, III) by its catalytic effect on the oxidation of 3-methyl-2-benzothiazolinone hydrazone with hydrogen peroxide Original Research Article

The iron catalyzed oxidation reaction of 3-methyl-2-benzothiazolinone hydrazone (MBTH) with hydrogen peroxide was studied kinetically by an initial-rate method. The reaction was followed by measuring the absorbance at 345 nm of the product. According to the kinetic study, a mechanism is proposed which leads to the following rate equation: R0 cat=[Fe]0[MBTH][H2O2]P[H+]+Q[H+][H2O2]+S[MBTH][H+][H2O2]+T[MBTH][H2O2]+U[MBTH][H+]+V[MBTH]The optimal conditions for the iron determination by the initial rate procedure were predicted using this rate equation. Under the optimum conditions (9 × 10−3 mol l−1 MBTH, 0.9 mol l−1 hydrogen peroxide, pH 2.7, 40°C), iron(II, III) can be determined in the range 1 to 1000 ng ml−1. The relative standard deviations are 6.2, 2.1 and 1.8% for the determination of 2, 10 and 60 ng ml−1 iron, respectively. This method was successfully applied to the determination of iron in tap and hot spring water samples.