High pressure liquid chromatographic determination of aflatoxins in soy sauce and fermented soybean paste

A procedure for the quantitative determination of aflatoxins B1, B2, G1, and G2 in soy sauce and fermented soybean paste is proposed using high pressure liquid chromatography with ultraviolet detection after CB extraction and SEP-PAK and preparative thin layer chromatographic cleanups. Recoveries of 71.3 to 89.3% were obtained for soy sauce spiked with 1, 5, 20, and 100 ppb aflatoxins. Similar recoveries (77.0 to 90.8%) were obtained with concentrated soy sauce and fermented soybean paste spiked at 20 and 100 ppb. In comparison with other procedures, the proposed procedure is relatively fast and precise and gives good recoveries. Aflatoxins were not stable in soy sauce. During storage, half of aflatoxins B1 and G1 were deteriorated at 60 and 120 days, respectively.