Development of an immunochromatographic assay for detection of aflatoxin B1 in foods

A rapid, signal step and sensitive immunochromatographic (IC) test for detection of aflatoxin B1 (AFB) in foods was described. Colloidal gold-labeled polyclonal antibody specific to AFB was used as the marker; AFB–BSA conjugate was the competitive antigen and goat-anti-rabbit antibody as control. Conditions for the analysis of AFB to be completed in less than 10 min were optimized. With visual observation, the lower limit was found to be around 2.5 ppb. For quantitative analysis by adopting a photometric strip reader, the lower detection limit was found to be around 0.05–0.1 ppb. The detection limit for AFB in food extract was around 2 μg/kg (ppb). The analytical recoveries for AFB added to extracts of rice, corn, and wheat and spiked directly to these foods range in 2–50 ppb were found to be 80.79% (CV, 10.92%) to 110.56% (CV, 7.95%). The CVs of all the assays were between 6.27% and 14.63%. Sixty seven naturally contaminated food samples were subjected to both IC strip and commercial ELISA kit test for AFB. Results showed a good correlation between these two methods with a square of correlation coefficient of 0.93 and slop of 1.13.