Thin layer chromatographic determination of aflatoxin in corn dust

Methods adopted by the AOAC and the American Association of Cereal Chemists for determining aflatoxin in corn were modified, and techniques were developed for application to samples of less than 1 to 10 g instead of the specified 50 g samples. Analysis included chloroform extraction of dust samples or dust collected from glass fiber filters, purification of extracts on a silica gel column of appropriate size, and measurement of aflatoxin by either 1- or 2-dimensional thin layer chromatography (TLC). The solvent for 1-dimensional TLC was chloroform-acetone-water (91 + 9 + 1). Solvents for 2-dimensional TLC were, first direction, ether-methanol-water (95 + 4 + 1, lined tank) and second direction, chloroform-acetone-water (91 + 9 + 1, unlined tank), or first direction, chloroform-acetone-water (91 + 9 + 1, unlined tank) and second direction, toluene-ethyl acetate-formic acid (60 + 30 + 10, unlined tank). When samples weighed less than or equal to 0.1 g, the entire concentrated extract was applied to the TLC plate. About 0.5-1.0 ng aflatoxin B1 could be detected on the plate, making the limit of detection about 9 ng/g for 0.1 g samples.