Voltammetric Behavior of the Insecticide Pymetrozine on a Mercury Meniscus Modified Silver Solid Amalgam Electrode

Abstract

A novel sensitive voltammetric method for the determination of the insecticide pymetrozine was designed using a solid working electrode. A mercury meniscus modified silver solid amalgam electrode in connection with differential pulse voltammetry was found to be appropriate for the determination of the insecticide. Pymetrozine provided one well-developed reduction peak suitable for analytical purposes at approximately −800 millivolts (vs. the Ag/AgCl electrode) in an acidic medium. The voltammetric behavior of pymetrozine as a function of the pH of the supporting electrolyte and scan rate was investigated using cyclic voltammetry and direct current voltammetry, respectively. The optimum conditions for determination using differential pulse voltammetry were in a Britton-Robinson buffer at pH 3.0 with a limit of detection of 5.4 × 10−8 moles per liter and a linear dynamic range from 2 × 10−7 to 1 × 10−4 moles per liter. The relative standard deviations of repeated determinations (n = 5) at various concentrations of pymetrozine did not exceed 3%. The results obtained using a silver solid amalgam electrode were compared with those achieved on hanging mercury drop electrode. The influence of possible interfering agents was also studied. The practical application of the method was verified by analysis of pesticide preparations and fortified river water.