Co-occurrence of aflatoxin B1, B2, G1, G2 and ochrotoxin A in Glycyrrhiza uralensis analyzed by HPLC-MS/MS

Licorice is widely used as additives in food and pharmaceutical industries and Glycyrrhiza uralensis is one of the main sources of licorice in China. G. uralensis may be contaminated by mycotoxins during growth, collection, transportation and, especially, storage. A rapid and highly sensitive method was firstly developed to determine aflatoxins (AFs) and ochratoxin A (OTA) in G. uralensis using high performance liquid chromatography coupled with tandem mass spectrometry (HPLC-MS/MS). Due to the complexity and high color of the investigated matrices, the proposed method is based on sonication extraction using a methanol/water mixture (80:20, v/v) followed by immunoaffinity column (IAC) cleanup. The limits of quantification (LOQs) of aflatoxins B1, B2, G1, G2 and OTA were 0.020, 0.015, 0.010, 0.015 and 0.010 μg/kg based on a signal-to-noise ratio of 10: 1, respectively. Good linearity was observed for all the analytes of interest, with correlation coefficients all higher than 0.995 within their respective linear ranges. Among the total of 15 G. uralensis samples collected from different areas in China, 6 were moldy due to inappropriate storage and 9 were fine without any visible mold contamination. The results showed that almost all the samples were contaminated with AFs and OTA. The AFs and OTA levels found in the moldy samples were higher than those not visibly moldy and two of the moldy samples exceeded the maximum limit set for OTA in licorice by EU regulation. This is the first report of the co-occurrence of AFs and OTA in G. uralensis in China.