A method for the detection of citrinin in food was developed by using high-affinity monoclonal antibodies against this mycotoxin. Samples were acidified and extracted with dichloromethane. The extracts were purified by liquid-liquid-partitioning with bicarbonate and analysed by an enzyme immunoassay (EIA). Positive results obtained by this screening assay were confirmed by HPLC and fluorescence detection. For this purpose, extracts were further purified by immunoaffinity chromatography. The detection limit for citrinin in food was 2μg/kg. This method was applied to 12 vegetarian "meat-like" products and 11 Asian foods purchased in retail stores in Bavaria, Germany. Using the EIA, citrinin could be detected in 8 vegetarian "meat-like" products and2 Asian foods at a concentration range of 22-105μg/kg. All but one positive result could be confirmed by HPLC analysis. All positive findings could be attributed to the use of rice fermented by Monascus spp. for food colouring. Furthermore, citrinin concentrations of 2800μg/kg and 157μg/kg were detected by HPLC analysis in 2 samples designated as natural food colorants. In 4 samples of red-mould rice from Japan, citrinin was found at lower concentrations (42-86μg/kg).
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