Voltammetric Determination of Neonicotinoid Pesticides at Disposable Screen-Printed Sensors Featuring a Sputtered Bismuth Electrode

This work reports the determination of 5 neonicotinoid pesticides (Clothianidin, Imidacloprid, Thiamethoxam, Nitenpyram and Dinotefuran) in water samples by cathodic differential pulse (DP) voltammetry at screen-printed disposable sensors featuring a sputtered bismuth thick-film working electrode, a Ag reference electrode and a carbon counter electrode. The performance of the bismuth thick-film electrodes was compared to that of a home-made bismuth thin-film electrode and a bismuth-bulk electrode. The electrodes were further characterized by electrochemical and optical techniques. The effect of the pH of the supporting electrolyte on the DP reduction currents of the 5 pesticides was studied. The limits of quantification (LOQs) in 4 water matrices (distilled water, tap water, mineral water and surface water) were in the range 0.76 to 2.10mgL(-1) but severe matrix effects were observed in the analysis of mineral and, especially, surface water samples. Using a solid-phase extraction (SPE) procedure using Lichrolut EN cartridges and elution with methanol, the matrix effects were substantially reduced and the LOQs were in the range 9 to 17 mu gL(.)(-1) The recoveries of surface water samples spiked with the 5 target neonicotinoids at two concentration levels (20 and 50 mu gL(-1)) were in the range 89 to 109% and the % relative standard deviations ranged from 4.3 to 7.2%.