ENZYME-IMMUNOASSAY FOR FUMONISIN B-1 APPLIED TO CORN-BASED FOOD

Polyclonal antibodies against fumonisin B-1 (FB1) were produced in rabbits after immunization with a FB1-keyhole limpet hemocyanin conjugate. Using these antibodies and a FB1-horseradish peroxidase conjugate in competitive direct enzyme immunoassay (EIA), the average detection limit for FB1 (buffer. solutions) was 0.17 ng/mL. The relative cross-reactions with FB1, fumonisin B-2, and fumonisin B-3 were 100 %, 24 %, and 55 %, respectively. Corn samples were extracted with methanol/water and the diluted raw extracts directly analyzed by EIA. The raw extracts were purified by employing strong ion-exchange (SAX) cartridges and reanalyzed by both EIA and a HPLC method. The recoveries for FB1 from artificially contaminated corn at levels of 50 and 500 ng/g were 59.7 % and 73.2 % after EIA analysis of the raw extracts; the corresponding values for SAX extracts were 53.5 % and 54.4 % (EIA) and 62.3 % and 65.6 % (HPLC), respectively. Food samples (n = 19) from German retail stores (some were import products from Italy) were analyzed: 16 were found to contain FB1 in a range from 12 to 1300 ng/g.