Comparison of different extraction and clean-up procedures for the determination of fumonisins in maize and maize-based food products

In order to optimize the analytical method for the determination of fumonisin B-1 (FB1) and fumonisin B-2 (FB2) in different maize products, five materials (maize flour, corn flakes, extruded maize, mu? ns and infant formula) were investigated under a variety of experimental conditions organized in a ruggedness test according to a factorial design. The influence of five factors (extraction solvent, extraction mode, volume of extraction solvent, test sample size and clean-up) on method performances was tested by four laboratories using spiked materials (0.5 mug/g and 1.5 mug/g FB1 + FB2) and naturally contaminated materials (ca 1.5 mug/g with FB1 + FB2). The end determination step was performed by high-performance liquid chromatography analysis of the o-phthaldialdehyde derivatized extracts. The ruggedness test permitted identification of two critical factors in the analysis of fumonisins in the above products, namely `extraction solvent' and `cleanup procedure'. In particular, the use of acetonitrile (ACN)-water (1 + 1, v + v) as extraction solvent and immunoaffinity column for clean-up provided better recovery of fumonisins and chromatographic resolution as compared with methanol (MeOH)-water (3 + 1, v + v) and strong anion exchange (SAX), respectively. However, phase separation occurring after extraction with ACN-water may have given incorrect results. Based on the information obtained with the present study it was possible to develop a new method horizontally applicable to all the above mentioned maize-based food matrices.