Simultaneous determination of fumonisin B1 and hydrolyzed fumonisin B1 in corn products by liquid chromatography/electrospray ionization mass spectrometry

A method for the simultaneous determination of fumonisin B-1 (FB1) and its major hydrolysis product (HFB1), which is known to be formed during alkaline treatment of fumonisin-containing corn meal, was devised to analyze the levels of these mycotoxins in corn products available on the German market. Liquid chromatography/electrospray mass spectrometry in combination with selected ion monitoring (SIM) was used for unambiguous detection of FB1 and HFB1 after extraction of samples with acetonitrile/methanol/water (25:25:50) and solid-phase C18 cleanup. Quantitation was carried out using labeled fumonisin FB1-D-6 as an internal standard. The detection limits achieved with this method were 8 ng/g for HFB1 (signal-noise ratio = 5:1) and 5 ng/g for FB1 (s/n = 5:1) using the protonated molecule signals m/z 406 and 722 in the SIM mode. A screening of several corn-containing foodstuffs, among them extrusion products and alkali-processed corn food such as tortilla chips, showed HFB1 and FB1 contamination with levels of 8-80 and 5-450 ng/g, respectively.