Determination of Butocarboxim Residue in Agricultural Products by HPLC with Post-Column Derivatization System

 SU-HSIANG TSENG*, PI-CHIOU CHANG AND SHIN-SHOU CHOU

 National Laboratories of Foods and Drugs, Department of Health, Executive Yuan, 161-2, Kuen Yang Street, Nankang 115, Taipei, Taiwan, R.O.C.

ABSTRACT

   A method using high performance liquid chromatography (HPLC) for the determination of butocarboxim in agricultural products was developed. Butocarboxim was extracted from samples with acetone and the extract solution was concentrated. The residue was dissolved in sodium chloride solution and partitioned with n-hexane. The aqueous phase was collected followed by extracted with dichloromethane, which was then evaporated to a volume of 2 mL prior to passing through an aminopropyl cartridge for sample clean-up. Determination of butocarboxim residue in crops was carried out by HPLC equipped with a post-column derivatization system and a fluorescence detector. HPLC separation was performed on a Lichrospher 60 RP-Select B column eluted with a mobile phase of acetonitrile-water (25:75, v/v). Butocarboxim was hydrolyzed at 90℃ under alkaline conditions and subsequently reacted with o-phthaldia ldehyde (OPA) / 2-mercaptoethanol reagent via a post-column reactor to generate a fluorophore, which was then detected with a fluorescence detector at Ex 340 nm and Em 455 nm. Average recoveries from radishes and bamboo sprouts, which were spiked with 0.1~0.3 and 0.2 ppm butocarboxim, respectively, were in the range of 81.9~82.6%. The detection limit was 0.05 ppm. No butocarboxim residue was detected in 10 commercial products including radishes, carrots, and bamboo sprouts.

Key words: agricultural products, butocarboxim, aminopropyl cartridge, high performance liquid chromatography (HPLC), post-column derivatization system, fluorescence detection.