1. Laboratory of Food Analysis, Faculty of Pharmaceutical Sciences, Ghent University, Harelbekestraat 72, B-9000 Ghent, Belgium, Toxi-Test n.v., Harelbekestraat 72, B-9000 Ghent, Belgium, and Agricultural Biotechnology Center, Szent-Györgyi Albert u. 4, H-2101 Gödöllö, Hungary