Determination of fumonisins B1 and B2 in maize-based baby food products by HPLC with fluorimetric detection after immunoaffinity column clean-up

A method for the determination of fumonisin B-1 (FB1) and B-2 (FB2) in different commercial maize-based products for infants and young children was developed and tested in a limited validation study involving 3 laboratories. The method used extraction at 55 C with an acidic mixture of methanol-acetonitrile-phosphate/citrate buffer, clean-up through immunoaffinity column and fumonisin determination by high performance liquid chromatography with automated pre-column derivatisation with 0-phthaldialdehyde. Recovery experiments were performed at five spiking levels in the ranges of 80-800 mu g/kg FB1 and 20-200 mu g/kg FB2. Mean recoveries ranged from 83 to 97% for FBI and from 61 to 78% for FB2. Relative standard deviations for within-laboratory repeatability (RSDr.) ranged from 5 to 12% for FBI and from 8 to 13% for FB2, whereas relative standard deviation for between-laboratory reproducibility (RSDR) ranged from 6 to 10% for FBI and from 9 to 16% for FB2. The limit of quantification of the method (signal to noise ratio of 6) was 2.8 mu g/kg for FBI and 2.2 mu g/kg for FB2. Fumonisins were found in 6 out of 19 maize-based baby foods obtained from the Italian retail market at levels up to 53 mu g/kg.