Determination of benzoylureas in tomato by high-performance liquid chromatography using continuous on-line post-elution photoirradiation with fluorescence detection

A photochemically induced fluorescence post-column method, with HPLC separa tion and fluorescence detection, was developed for the determination of fiv e naturally non-fluorescent benzoylurea insecticides: diflubenzuron, triflu muron, hexaflumuron, lufenuron and flufenoxuron. The applicability of the m ethod to the determination of insecticides in spiked tomato was evaluated. Samples were extracted into ethyl acetate and further cleaned-up by solid-p hase extraction using an aminopropyl-bonded silica cartridge. The interfere nces due to the matrix effect were eliminated using matrix matched standard s. Linear dynamic ranges were established over more than two orders of magn itude. The limits of detection ranged from 5 to 3,1 ng ml(-1) (or 0.5 and 2 .1 mug kg(-1) in the vegetable samples), with relative standard deviations lower than 5.0%, using blank tomato extract. Mean recoveries ranged from 79 to 102%. (C) 2001 Elsevier Science B.V. AU rights reserved.