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

Abstract

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, cornflakes, 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 μg/g and 1.5 μg/g FB1 + FB2) and naturally contaminated materials (ca 1.5 μg/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.