Determination of fumonisins B1 and B2 in corn flakes by HPLC and immunoaffinity clean up

The determination of fumonisins in cornXakes is a challenging matter as the actually available methods for the analysis of corn do not perform well when applied to this more complex matrix. After testing several factors that may aVect the analytical performance, an accurate method for the determination of fumonisin B1 (FB1) and B2 (FB2) in cornXakes has been developed. The method uses immunoaYnity chromatography for clean-up and high performance liquid chromatography (HPLC) for quantiWcation of the toxins. Samples were extracted twice with acetonitrile± methanol± water (25:25:50) and the combined extracts were diluted with phosphate buVered saline (PBS) and applied to a FumoniTestTM immunoaYnity column. After washing with PBS, fumonisins were eluted from the column with methanol and reacted with o-phthaldialdehyde /2-mercaptoethanol to form Xuorescent derivatives. Fumonisin derivatives were analysed by reversed phase HPLC with Xuorometric detection using methanol± 0.1M phosphate buVer (77:23; pH adjusted at 3.35) as mobile phase. The average recoveries for FB1 and FB2 spiked in the ranges of 0.33± 2.80 ·g/g and 0.17± 1.40 ·g/g were 102.6% and 95.1%, respectively, with average relative standard deviations of 9% and 8% . The limit of quantiWcation for FB1 and FB2 was 0.005 ·g/g based on a signal-to-noise ratio of 6:1 by using a sensitive Xuorescence detector. The method was used to analyse 18 cornXakes and cornXake cereals samples for FB1 and FB2 contamination. All but one sample were found to be contaminated, with maximum FB1 and FB2 concentrations of 1.092 ·g/g and 0.235 ·g/g, respectively. Mean FB1 and FB2 concentrations were 0.157 ·g/g and 0.036 ·g/g, respectively.