Sensitive Enzyme-Linked Immunosorbent Assay for the Mycotoxin Zearalenone in Barley and Job's-Tears

An easy, sensitive, competitive indirect enzyme-linked immunosorbent assay (CI-ELISA) for zearalenone in barley and Job's-tears was established. To improve sensitivity of the assay system for zearalenone, a solid phase antigen was prepared by affinity purification. This assay system uses a purified antigen and specific monoclonal antibodies for zearalenone. Consequently, the detection limit of zearalenone by CI-ELISA was increased to 0.2 ng/mL (equivalent to 10 ng/g in barley and Job's-tears). Zearalenone in barley and Job's-tears samples could be determined in the range of 25-1000 ng/g using method A (methanol-water and dichloromethane extraction) and method B (methanol-water alone) as sample preparation. The average recoveries of zearalenone from barley samples were observed to be 106% (mean CV, 10.3%) by method A and 98% (mean CV, 7.5%) by method B; also, those of zearalenone from Job's-tears samples were observed to be 96% (mean CV, 9.4%) by method A and 102% (mean CV, 6.5%) by method B. There was little or no difference between method A and method B for the recovery. For the benefit of a facile sample preparation, unknown amounts of zearalenone in barley and Job's-tears samples were assayed by method B. The results obtained by CI-ELISA were closely correlated with those of high-performance liquid chromatography