Mass Spectrometry/Mass Spectrometry Study on the Degradation of B-Aflatoxins in Maize with Aqueous Citric Acid

Abstract

Degradation of B-aflatoxins in maize by means of 1N aqueous citric acid was confirmed by the AFLATEST immunoaffinity column method, High Performance Liquid Chromatography (HPLC), tandem mass spectrometry (MS/MS) and computational information. The AFLATEST and HPLC assays showed that 96.7% degradation occurred in maize contaminated with 93 ng g^-1 when treated with the aqueous citric acid. Two major products, produced during the acidification process, were identified by their corresponding mass spectral data: a nonfluorescent compound lacking the lactone group evidenced by the presence of a peak m/z 286 and a nonfluorescent compound retaining the difurane moiety but lacking the lactone carbonyl and the cyclopentenone ring of the AFB1, also suggested by the peak m/z 206; the title fragments correspond to molecular ions in agreement with their respective molecular weights. According to the theoretical calculations, applying density functional theory, it was confirmed that the active site may be assigned to the carbonylic carbon of the lactonic moiety.