Liquid chromatographic detection of fumonisins in rice seed
2008
Kushiro, M.(National Food Research Inst., Tsukuba, Ibaraki (Japan)) | Nagata, R. | Nakagawa, H. | Nagashima, H.
Fumonisins are mycotoxins mainly produced by Fusarium verticillioides, which is a major pollutant to corn. On the other hand, rice adherent fungus Gibberella fujikuroi is taxonomically near to F. verticillioides, so that the potential risk of fumonisin contamination in rice is significant. Previously we developed an efficient extraction procedure (submergence extraction) and a sensitive detection method (liquid chromatography with tandem mass spectrometry (LC-MS/MS)) for the determination of fumonisins in brown rice. In this study, we attempted to detect fumonisins in rice seed in the husk by an extension of the method for fumonisin analysis in brown rice, according to the request to detect fumonisins in rice before threshing. As a result, extraction with submergence was found to be effective in rice seed as well as in brown rice, but more effective way was to use a different solid phase extraction (SPE) cartridge for the purification of fumonisins from rice seed extract. With submergence extraction and purification with the newly selected SPE cartridge, fine recovery was achieved for clean rice seed samples in spike and recovery tests. About five hundred grams of rice seed sample was divided to seven subsamples, and ten grams from each subsample was subjected to analysis. The conventional determination method, liquid chromatography using fluorescence detection (HPLC-FL) with precolumn derivatization, could not detect any fumonisins in any of the analytical samples, while fumonisins were detected in two of seven samples by use of LC-MS/MS. This is the first case of the natural occurrence of fumonisins in domestic Japanese rice. The importance of sampling in non-homogeneous samples like rice seed was also suggested.
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