SUPERCRITICAL-FLUID EXTRACTION AND HPLC ANALYSIS OF BENZIMIDAZOLE FUNGICIDES IN POTATO, APPLE, AND BANANA

An analytical method employing supercritical fluid extraction (SFE) of the benzimidazole fungicides thiabendazole, benomyl/carbendazim, and thiophanate-methyl was developed and tested with potato, banana, and apple matrices. Ion-pairing HPLC coupled with UV absorbance or fluorescence detection was used for analysis. Sample preparation involved shredding a 100 g sample, mixing a 3 g subsample with 2 g of Hydromatrix, and packing a 10 mL vessel. Optimal SFE conditions were determined by varying the amount, density, and flow rate of CO2, extraction temperature, type and amount of solvent modifier, and trapping/elution conditions of the extracted pesticides. Optimal conditions for extraction were obtained at 400 atm, 60 degrees C, 90 g of CO2, 3% methanol modifier, and 2 mL/min flow rate. The extracts were collected on a 1 mL C-18 trap at 25 degrees C and eluted with 10 mL of methanol. Potato, apple, and banana extracts were analyzed by HPLC without additional cleanup. Recoveries were 90 +/- 12% for the benzimidazole fungicides in fortified samples. Incurred potato and banana samples were also analyzed.