Development of a novel immunoaffinity column for aflatoxin analysis using an organic solvent-tolerant monoclonal antibody.

An organic solvent-tolerant monoclonal antibody specific to aflatoxins B(1), B(2), G(1), G(2), and M(1) (AFB(1), AFB(2), AFG(1), AFG(2), and AFM(1)) was prepared. In an indirect competitive enzyme-linked immunosorbent assay, the half maximal inhibitory concentration (IC(50)) values were 1.9, 2.1, 2.1, 2.4, and 2.8 ng/mL for AFB(1), AFB(2), AFG(1), AFG(2), and AFM(1), respectively. Antibody reactivity was retained at 40% methanol concentration or at acetonitrile concentrations up to 40%. An immunoaffinity column (IAC) was prepared using agarose gel beads with bound antibody. The IAC retained the tested AFs that were 89, 90, 95, 90, and 89% for AFB(1), AFB(2), AFG(1), AFG(2), and AFM(1) at 20% acetonitrile concentrations or that were 81, 87, 79, and 83% for AFB(1), AFB(2), AFG(1), and AFG(2) at 60% methanol concentrations. Roasted peanuts and seven kinds of spices were spiked with 8.0, 1.0, 6.0, and 1.0 ng for AFB(1), AFB(2), AFG(1), and AFG(2) per 1 g sample and extracted with 90% acetonitrile. The roasted peanuts and cayenne pepper out of the spices were also extracted with 70% methanol. The extracts were diluted 5-fold with phosphate-buffered saline and applied to the IAC. The spiked aflatoxins were recovered with satisfactory rates: 78 (RSD, 2.1%) to 127% (RSD, 1.7%). The developed IAC was used for the analysis of aflatoxins in naturally contaminated samples of roasted peanuts and cayenne pepper. The newly developed IAC showed substantially organic solvent tolerance at the concentration that could not be used for existing IACs, and the column showed good ability to clean up samples for food analysis.