Determination of zearalenone in corn by means of immunoaffinity clean-up and high-performance liquid chromatography with fluorescence detection

A rapid and accurate method to quantify zearalenone in corn is described. The method uses immunoaffinity chromatography for purification and high-performance liquid chromatography (HPLC) for detection and quantification of the toxin. Corn samples were extracted with acetonitrile-water (90:10, v/v) and the extract was diluted with water (1:10, v/v) and applied to a Vicam Zearala Test immunoaffinity column. The column was washed with water and zearalenone was eluted with methanol and quantified by reversed-phase HPLC with fluorometric detection (lambda(ex) = 274 nm, lambda(em) = 440 nm) using acetonitrile-water-methanol (46:46:8, v/v) as mobile phase. Zearalenone recoveries from the ZearalaTest column were higher than 95%, and the column can hold a maximum of 4.0 mu g of toxin. Average recoveries of zearalenone from corn spiked at levels of 0.1-10 mu g/g ranged from 93 to 99.5%, with relative standard deviations of <6%. The detection limit was 3 ng/g based on a signal-to-noise ratio of 3:1. Comparative analysis of 14 naturally contaminated samples using this method and the AOAC official method 985.18 showed a reasonable correlation (r = 0.87). Advantages of the immunoaffinity method as compared to the AOAC method are discussed. (C) 1998 Elsevier Science B.V. All rights reserved.