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

摘要

A flow injection analysis (PIA) system, combined with photochemical induced fluorescence (PIP) detection is devel- oped 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 334 nm and an emission maximum at 377 nm. The linear concentration range of application was 1.0-60.0 ng ml~(-1) of imidacloprid, with a relative standard deviation of 2.1 % (for a level of 10ngml~(-1)) and a detection limit of 0.3 ngml~(-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 (-test). Recovery levels of the method reached around 100% in all cases.