Application of coupled-column liquid chromatography combined with post-column photochemically induced fluorimetry derivatization and fluorescence detection to the determination of pyrethroid insecticides in vegetable samples.

This study reports the first application of coupled-column liquid chromatography-photochemically induced fluorimetry-fluorescence detection (LC-LC-PIF-FD), demonstrating its potential for the quantitative and selective detection of seven pyrethroids in vegetable samples such as cucumber, green bean, tomato and aubergine. An internal surface reversed-phase (ISRP) column coupled to a C18 column for analyte clean-up and determination were used, respectively. In comparison with a C18 column, the ISRP substantially improved the separation between analytes and interferences from the vegetable matrix. The limits of detection ranged from 0.01 to 0.22 microg kg(-1) in the vegetable samples (equivalent to 0.01 and 0.13 microg L(-1) in the extract injected), and limits of determination ranged from 0.56 to 8.33 microg kg(-1) in the vegetable samples (equivalent to 0.34 and 5.00 microg L(-1) in the extract injected). Samples were extracted into dichloromethane to yield mean recoveries at two levels of concentration between 72.8 and 110.0% in all cases. Relative standard deviations were lower than 11%.