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 B1 (FB1) and fumonisin B2 (FB2) in different maize products, five materials (maize flour, corn flakes, extruded maize, muffins 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 mg/kg and 1.5 mg/kg FB1+FB2) and naturally contaminated materials (ca. 1.5 mg/kg with FB1+FB2). The end determination step was performed by high-performance liquid chromatography analysis of the o-phthaldialdehyde derivatised extracts. The ruggedness test permitted to identify two critical factors in the analysis of fumonisins in the above products, namely ¡§extraction solvent¡¨ and ¡§clean-up procedure¡¨. In particular, the use of ACN+water (1+1, v+v) as extraction solvent and immunoaffinity column for clean-up provided better fumonisins recovery and chromatographic resolution as compared to MeOH+water (3+1, v+v) and strong anion exchange (SAX), respectively. However, phase separation occurring after extraction with ACN+water may have given uncorrect 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.