Coupled-column liquid chromatography method with photochemically induced derivatization for the direct determination of benzoylureas in vegetables

✍ Scribed by María Dolores Gil García; Dolores Barranco Martínez; María Martínez Galera; Piedad Parrilla Vázquez

• Publisher: John Wiley and Sons
• Year: 2004
• Tongue: English
• Weight: 180 KB
• Volume: 27
• Category: Article
• ISSN: 1615-9306
• DOI: 10.1002/jssc.200301661

✦ Synopsis

Abstract

The coupled‐column (LC‐LC) system, consisting of a first column packed with internal surface reversed phase (ISRP) (50×4.6 mm ID) and a Chrompack C~18~ (100×4.6 mm ID) as second column, allowed the simultaneous determination of five benzoylurea insecticides in dichloromethane (CH~2~Cl~2~) 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 μg L^–1^ of pesticide (equivalent to 0.14–0.65 μg kg^–1^ in vegetable samples) and limits of determination ranged from 4.0 to 10.0 μg L^–1^ (equivalent to 2.7–6.7 μg kg^–1^). Linearity of the method was established between 2 and 1800 μg 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) spiked at two levels of concentration (10.0 and 33.3 μg kg^–1^). The combination of the LC‐LC system with PIF detection provides a sensitive, selective, and rapid method for the determination of pesticides in vegetable samples at levels lower than the maximum residue levels (MRLs) established for these compounds by Spanish legislation.