Determination of pyrethroids in vegetables by HPLC using continuous on-line post-elution photoirradiation with fluorescence detection

Seven naturally non-fluorescent pyrethroids: fenpropathrin, cyfluthrin, deltamethrin, fenvalerate, acrinathrin, tau-fluvalinate and bifenthrin were determined using HPLC with a photochemically-induced post-column method, and fluorescence detection. The method was applied to the analysis of these insecticides in cucumber. Samples were extracted with dichloromethane and further cleaned up by SPE using a florisil cartridge. Matrix effect was overcame using matrix-matched standard for building up the calibration graphs and, in this way, dynamic ranges were established over more than two orders of magnitude. The limits of quantification ranged from 8 to 90 ng ml(-1) (corresponding to 0.8 and 9 mug kg(-1) in the vegetable sample), with relative standard deviations less than 8.6% using blank cucumber extract. Mean recoveries ranged from 95 to 116%. (C) 2001 Elsevier Science B.V. All rights reserved.