Abstract:

A method using gas chromatography (GC) was established for the determination of dicofol residue in vegetables and fruits. Samples were extracted with a mixture of acetone and n-hexane. The resulting extract was then cleaned up on a Florisil column and treated with a mixture of absolute ethanol and aqueous potassium hydroxide solution. The n-hexane (upper layer) was harvested and washed with 20 g/L aqueous sodium sulfate solution twice prior to the injection into a GC system equipped with an electron capture detector. The external standard method was adopted for dicofol quantification. The figures of merit of the developed method such as sensitivity, accuracy and precision were evaluated. The limit of detection for dicofol was 0.005 mg/kg. Average recoveries for dicofol in 10 species of real samples separately spiked at 3 levels in 10 replicates each were ranged from 70.23% to 98.10%, with a RSD range between 3.21% and 10.12%. This method may satisfy the requirements of the national standards for pesticide residue determination.

Key words: gas chromatography, fruits and vegetables, dicofol, alkaline hydrolysis