Coupled-column liquid chromatography method with photochemically induced derivatization for the direct determination of benzoylureas in vegetables
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Author/sGil García, María Dolores; Barranco Martínez, Dolores; Martínez Galera, María; Parrilla Vázquez, Piedad
The coupled-column (LC-LC) system, consisting of a first column packed with internal surface reversed phase (ISRP) (50x4.6 mm ID) and a Chrompack C18 (100x4.6 mm ID) as second column, allowed the simultaneous determination of five benzoylurea insecticides in dichloromethane (CH2Cl2) extracts of vegetable samples without any clean-up step. This system was combined with a photochemically induced fluorescence (PIF) post-column derivatization in order to provide strongly fluorescent photoproducts from the non-fluorescent benzoylureas. Limits of detection ranged from 0.21 to 0.98 ug L–1 of pesticide (equivalent to 0.14–0.65 ug kg–1 in vegetable samples) and limits of determination ranged from 4.0 to 10.0 ug L–1 (equivalent to 2.7–6.7 ug kg–1). Linearity of the method was established between 2 and 1800 ug L–1, depending upon the compound. Validation of the total method was performed by randomly analyzing recoveries of four vegetable samples (aubergine, cucumber, green bean, and tomato) spike...
Photochemically induced fluorescence