Rapid immunoaffinity-based method for determination of zearalenone in corn by fluorometry and liquid chromatography

An immunoaffinity-based method was developed to determine zearalenone in corn. Corn samples were extracted in acetonitrile-water (90 + 10, v/v), applied to an immunoaffinity column, and eluted with methanol. The isolated toxin was quantitated either by reaction with aluminum chloride hexahydrate (AlCl3.6H2O) prior to measurement with a fluorometer or injection into a liquid chromatographic (LC) system with a fluorescence detector. Performance was evaluated in terms of antibody specificity, limit of detection, percentage recovery, precision, column capacity, assay linearity, and comparison with AOAC Official Method 985.18. With the immunoaffinity column cleanup procedure, only zearalenone and its metabolites were recognized by the antibody (> or = 75% recovery). Limits of detection were 0.10 microgram/g for the fluorometer and 0.10 or 0.0025 microgram/g (sensitive method) for the LC method. Percentage recovery averaged 105% (fluorometer) and 93% (LC method), with average relative standard deviations (RSDs) of 15.7 and 9.3%. Naturally contaminated samples gave comparable RSDs of 8.3 and 9.9% for the fluorometer and LC methods, respectively. Column capacity was 4.0 micrograms with 89% recovery. Assay linearity was comparable for both methods (r2 = 0.998). Optimum assay ranges were 0.10-5.0 micrograms/g for the fluorometer and 0.10-50 or 0.0025-5.0 micrograms/g (sensitive method) for the LC method. Comparative analysis of 17 naturally contaminated corn samples using Zearala Test LC and the official AOAC LC method for detection of zearalenone showed that Zearala Test is statistically comparable to the AOAC Official Method 985.18 (r2 = 0.747).