[Extraction and analysis of profenofos residue in tomato and cabbage by gas chromatography-flame photometric detector].
A quick and effective extraction and clean-up method of profenofos residue in tomato and cabbage is presented. Tomato and cabbage samples were homogenized with a mixture of acetone-hexane (1:1, V/V) using a mechanical homogenizer. The resultant homogenate was cleaned-up by adding active carbon and then filtered under reduced pressure. The filter cake was extracted twice with the same solvent mixture. The filtrates were combined and transferred into a separatory funnel. The organic layer was separated and evaporated to dryness using a rotary evaporator. The residue was dissolved in 2 mL of acetone and transferred into a small glass vial and then determined by GC on a 5% OV-101 Chromosorb W-HP column with flame photometric detector. The results showed that this analytical method can be used for an accurate determination of profenofos residues in tomato and cabbage. The minimum detectable concentration of profenofos in samples was 0.06 mg/kg. The recoveries of profenofos in tomato and cabbage were in the range of 96.2%-105.9% and 94.7%-102.3%, respectively. The relative standard deviations were in the range of 3.7%-4.9% and 3.7%-5.0%, respectively. The tomato and cabbage samples were collected 3 weeks after applying profenofos in the field, and the contents of profenofos were determined. The average contents of profenofos in tomato and cabbage were (13.8 +/- 0.8) mg/kg and (14.4 +/- 0.7) mg/kg, respectively.