Analysis of fumonisins B1 and B2 in spices and aromatic and medicinal herbs by HPLC-FLD with on-line post-column derivatization and positive confirmation by LC-MS/MS.

Fumonisins are produced by the fungus Fusarium verticillioides, which are known to cause fatal diseases in some animals and humans. Here, we describe a sensitive, reproducible and reliable analytical method for the quantitative determination of fumonisins B(1) (FB(1)) and B(2) (FB(2)) in 112 spices and aromatic and medicinal herbs marketed in China. This method is based on high performance liquid chromatography and fluorescence detection (HPLC-FLD) coupled to a new on-line post-column derivatization using ortho-phthaldialdehyde with 2-mercaptoethanol and immunoaffinity column clean-up. Under the optimized experimental conditions, a complete separation of FB(1) and FB(2) was obtained using a Synergi C(18) column and a gradient elution at 0.8 mL min(-1) with methanol and 0.1 M phosphate buffer at pH 3.15. The limits of detection for FB(1) and FB(2) were both 40 μg kg(-1). Good recoveries were found for spiked samples with FB(1) and FB(2), ranging from 82.34% to 98.16% for FB(1) and from 72.58% to 97.10% for FB(2), with relative standard deviation (RSD) < 7.0%. 5 spices, 11 aromatic herbs and 96 medicinal herbs including 93 normal samples and 19 visibly moldy samples, which were spoiled artificially, were analyzed. The results showed that 8 (42.1%) visibly moldy samples and 8 (8.6%) normal samples were contaminated with FB(1) at mean contents of 129.0 and 165.9 μg kg(-1), and with FB(2) at 1745.0 and 256.8 μg kg(-1), respectively. Positive confirmation of detected samples was performed by liquid chromatography tandem electrospray ionization mass spectrometry (LC-ESI-MS/MS), using a triple quadrupole analyzer and operated in the multiple reaction monitoring mode.