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 2.10 mg L −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 µg L −1 . The recoveries of surface water samples spiked with the 5 target neonicotinoids at two concentration levels (20 and 50 µg L −1 ) were in the range 89 to 109 % and the % relative standard deviations ranged from 4.3 to 7.2 %.