SENSITIVE IMMUNOASSAY FOR FUMONISIN B-1 IN CORN

Polyclonal antibodies against fumonisin B-1 (FB1) were produced in rab bits after immunization with FB1 conjugates. Protection of the amino g roup prior to coupling the carboxylic acid of FB1 to human serum album in, and then deprotecting the amine before immunization, generated hig h-affinity antibodies. The antibodies produced were specific to fumoni sins and their hydrolyzed products (HFB1, HFB2) but not to any other m ycotoxins commonly found in grains. The relative crossreactivities of FB1, fumonisin B-2 (FB2), fumonisin B-3 (FB3), HFB1, and HFB2 were 100 %, 55%, 13%, 11%, and 3%, respectively. Using these antibodies, a sens itive indirect competitive ELISA was developed. The detection limit an d IC50 for FB1 in water were 0.05 and 0.66 ng/mL, respectively. The li near range was determined to be 0.05-0.75 ng/mL. The method was applie d directly to 75% methanol extracts of corn. Recoveries of FB1 were be tter than 87% from 10 to 10 000 ng/g at five levels of fortification. The detection limit in corn was 5 ng/g.