Development and application of kinetic-spectrophotometric method for analysis of diflubenzuron in soil samples using SPE followed by HPLC method

Abstract

The purpose of this paper is to present a new sensitive and simple kinetic-spectrophotometric method for the determination of the insecticide diflubenzuron (DFB). The kinetic method is based on the inhibition effect of DFB on the oxidation of sulfanilic acid (SA) by potassium periodate in acetate buffer in the presence of Fe(III) ion as a catalyst and 1,10-phenantroline. The reaction was monitored spectrophotometrically by measuring the increase in absorbance with time of the reaction product at 368 nm. Diflubenzuron was determined with linear calibration graph in the interval from 0.0374 to 0.374 μg/cm3 and from 0.374 to 26.18 μg/cm3. The detection limit and quantification limit of the method with 3σ criteria were 0.0039 μg/cm3 and 0.0131 μg/cm3, respectively. The relative standard deviations for five replicate determinations of 0.0374, 0.188 and 0.374 μg/cm3 DFB were 2.24, 2.11 and 1.10%, respectively. The method was successfully applied to determine DFB residues in soil samples. Solid-phase extraction (SPE) was used for extraction of DFB from soil and samples with Chromabond® (Macherey-Nagel) C18 cartridges. The HPLC method was used as a comparative method to verify the results. The results obtained by two different methods showed good agreement.