Voltammetric Monitoring of Photodegradation of Clothianidin, Nitenpyram and Imidacloprid Insecticides Using a Tricresyl Phosphate-Based Carbon Paste Electrode

A voltammetric investigation of two commercial neonicotinoid insecticides, Clothianidin (Clo) and Nitenpyram (Nit), was carried out and completed with the third one, Imidacloprid (Imc), from a previous study when using two different types of carbon paste electrodes made from graphite powder and silicone oil (SO-CPE) or tricresyl phosphate as the binder (TCP-CPE). For all substances of interest, the latter has been found superior with respect to the signal-to-noise characteristics and the overal electroanalytical performance. Subsequently, a new method employing the direct differential pulse voltammetry (DPV) and the TCP-CPE has been proposed for the determination of Clo and Nit at the low μg mL-1 concentration level; all the key parameters being applicable also to Imc. Finally, the procedure combining DPV with the TCP-CPE could be applied for the monitoring of the photolytic and TiO2-assisted photocatalytic degradation of Clo, Nit, and Imc via their voltammetrically detectable disappearance, when the quantitative and kinetic data obtained have agreed well with the results of the reference HPLC/DAD measurements.