Flow injection analysis of the insecticide imidacloprid in water samples with photochemically induced fluorescence detection

A flow injection analysis (FIA) system, combined with photochemical induced fluorescence (PIF) detection is developed for the sensitive and rapid determination of imidacloprid. It is based on the conversion of imidacloprid into the fluorophore 1-(6-chloro-3-pyridyl-methyl)-2-(hydroxyimino)-3,4-didehydroimidalozolidene. In an aqueous medium, this compound shows native fluorescence with an excitation maximum at 334nm and an emission maximum at 377nm. The linear concentration range of application was 1.0–60.0ngml−1 of imidacloprid, with a relative standard deviation of 2.1% (for a level of 10ngml−1) and a detection limit of 0.3ngml−1. The method was applied to check whether imidacloprid was present above this limit in waters from Cuenca and Granada (Spain). It was validated applying a recovery test (Student’s t-test). Recovery levels of the method reached around 100% in all cases.