Determination of zearalenone and related metabolites in porcine urine by modified enzyme-linked immunosorbent assay.

A direct competitive enzyme-linked immunosorbent assay (ELISA) was modified for the determination of zearalenone and zearalenois in porcine urine. In the modified procedure, standard or unknown concentrations of zearalenone were added to all wells, followed by rapid addition of zearalenone-horseradish peroxidase conjugate, whereas in previous methods, zearalenone and zearalenone-horseradish peroxidase were mixed and then added to microtiter wells. The modification increased the number of urine samples that could be analyzed per assay. The linear portion of the modified ELISA standard curve covered the range of 10-500 ng zearalenone/mL. Average recovery of zearalenone from spiked urine was 91, 101, 95, 107, 136, 112, and 120% for 1, 10, 25, 50, 100, 250, and 500 ng zearalenone/mL urine, respectively. Mean within-assay coefficient of variation for each concentration of zearalenone in 5 standard curves was 5.95%. Between-assay coefficients of variation for concentrations of zearalenone equivalents in lower and upper regions of the standard curve were 10.9% (n = 18) and 8.8% (n = 20), respectively. Analysis of urine samples showed that a gilt excreted 5.3% of ingested zearalenone in the 8 h following ingestion, with an average excretion rate of about 100 micrograms zearalenone equivalents/h.