A Clean-up Method for the Detection of Carbamate Insecticides in Foods by Thin-Layer Chromatography

Abstract

A clean-up method suitable for the detection of carbamate insecticides in unpolished rice, green tea, cabbage, and spinach by thin-layer chromatography was developed. The clean-up method consists of the treatment of food extracts with a coagulating solution, followed by washing with an alkaline solution. Washing with sodium benzoate solution is effective for removing most of caffeine in the extract of green tea. Washing with an acidic solution is necessary for the removal of contaminants in the extracts of cabbage and spinach. By this method, carbaryl (0.1 ppm) added to the food was finally recovered in an ethanolic solution (100 μl), and the detection limit on thin-layer plates was 4-5 μl. The detection of Suncide, Meobal, and Osbac from the food fortified at 1 ppm each was successful by the application of 3-7 μl of the finally obtained solution to thin-layer chromatography.