Simple chromatographic determination of aflatoxins in Korean fermented soybean products doenjang, ganjang, and gochujang, with comparison of derivatization methods

Korean fermented soybean products doenjang, ganjang, and gochujang are vulnerable to contamination with aflatoxigenic fungi in the open fermentation environment. Therefore, simple and effective methods to determine aflatoxins (AFs) in these complex food matrices are needed. High-performance liquid chromatography with fluorescence detection using two derivatization methods for AF determination in three fermented soybean products was optimized and validated. Pre-column derivatization (preCD) of the AF extracts was performed using trifluoroacetic acid, and post-column derivatization (PCD) was performed in a photochemical reactor for enhanced detection. Both derivatization methods resulted in acceptable performances for linearity (R2 > 0.999), recovery (71–118%), and precision (< 10.6%) values. Recovery and precision with preCD and PCD were similar, but the limit of detection was superior with PCD. When these analytical methods were applied to commercially available fermented soybean products, the AF levels of all commercial products were ranged from not detected to 6.06 μg/kg.