Fluorimetric determination of aromatic pesticides in technical formulations. Effects of solvent and of ultraviolet photolysis.

The effects of solvent and of ultraviolet (UV) photolysis on the fluorescence intensity of several aromatic pesticides including bendiocarb, chlorophacinone, coumatetralyl and pirimiphos-methyl were investigated. The type and polarity of solvent (acetonitrile, dimethylsulfoxide, methanol, ethanol and 2-propanol) were shown to play an important role in the limits of detection (LOD) of the method. UV photolysis provoked a decrease of the fluorescence signal more or less marked, depending of the structure of the pesticide. Analytical figures of merit were evaluated for the determination of pesticides under optimal conditions. The method exhibited satisfactory analytical performances. The linear dynamic ranges were obtained over more than two orders of magnitude. The LOD ranged from 0.03 to 20 ng/ml, according to the compound. The relative standard deviations were between 5.5 and 6.1%. Examples of application to the determination of pesticides in technical formulations are presented. The mean recoveries ranged from 86 to 116%. It shows the usefulness of this technique for pesticide analysis.