Determination of fumonisins B 1 and B 2 in cornflakes by high performance liquid chromatography and immunoaffinity clean-up (original) (raw)

The determination of fumonisins in cornXakes is a challengin g 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 B 1 (FB 1 ) and B 2 (FB 2 ) in cornXakes has been developed. The method uses immunoaYnity chromatography for clean-up and high performance liquid chromatograph y (HPLC) for quantiWcation of the toxins. Samples were extracted twice with acetoni-trile± methanol± water (25:25:50) and the combined extracts were diluted with phosphate buVered saline (PBS) and applied to a FumoniTest TM 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± 0.1 M phosphat e buVer (77:23; pH adjusted at 3.35) as mobile phase. The average recoveries for FB 1 and FB 2 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 FB 1 and FB 2 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 FB 1 and FB 2 contamination. All but one sample were found to be contaminated, with maxi-mum FB 1 and FB 2 concentrations of 1.092 ·g/g and 0.235 ·g/g, respectively. Mean FB 1 and FB 2 concentrations were 0.157 ·g/g and 0.036 ·g/g, respectively.