Polarographic determination of pyrethroid residues in stored cereals

A new method for determination of the total cyanopyrethroid residue concentration in stored cereals by differential-pulse polarography is proposed. Cyanopyrethroids were previously extracted with a non-polar solvent and purified by solid-phase extraction. The total pyrethroid residue concentrations are determined by differential-pulse polarography of 3-phenoxybenzaldehyde formed quantitatively by rapid and reproducible alkaline alcoholysis of the sample. The method is linear, quantitative and reproducible for maize and wheat analysis in the range 0.1-3.0 mg kg-1. A thin-layer chromatographic method for identification of six widely used cyanopyrethroids in the sample is described. The electronic reduction process of 3-phenoxybenzaldehyde is examined and the reduction products isolated and identified.