Determination of fumonisins B1 and B2 in Portuguese maize and maize-based samples by HPLC with fluorescence detection

Fumonisins B-1 (FB1) and fumonisin B-2 (FB2) are the main members of a family of mycotoxins produced by Fusarium verticillioides, Fusarium proliferatum, and other fungi species of the section Liseola. The present work shows the results of comparative studies using two different procedures for the analysis of fumonisins in maize and maize-based samples. The studied analytical methods involve extraction with methanol/water, dilution with PBS, and clean-up through immunoaffinity columns. Two reagents (o-phthaldialdehyde and naphthalene-2,3-dicarboxaldehyde) were studied for formation of fluorescent derivatives. The separation and identification were carried out by high-performance liquid chromatography with fluorescence detection. The optimized method for analysis of fumonisins in maize involved extraction with methanol/water (80:20), clean-up with an immunoaffinity column, and derivatization with naphthalene-2,3-dicarboxaldehyde (NDA). The limit of detection was 20 mu g kg(-1) for FB1 and 15 mu g kg(-1) for FB2. Recoveries of FB1 and FB2 ranged from 79% to 99.6% for maize fortified at 150 mu g kg(-1) and 200 mu g kg(-1), respectively, with within-day RSDs of 3.0 and 2.7%. The proposed method was applied to 31 samples, and the presence of fumonisins was found in 14 samples at concentrations ranging from 113 to 2,026 mu g kg(-1). The estimated daily intake of fumonisins was 0.14 mu g kg(-1) body weight per day.