Variation Among Grain Elevator Testing Sites and Analytical Cross-Reactivity of Commercial Immunoassay Kits for Deoxynivalenol Detection in Maize.

Commercial immunoassay-based test kits are widely used for rapid screening of deoxynivalenol (DON) in maize; however, inconsistent results are frequently observed under commercial testing conditions. This study evaluated two distinct contributors to such variability: analytical cross-reactivity of commercial DON immunoassays and between-site variability arising from routine grain elevator testing practices. Under controlled laboratory conditions, all kits accurately measured DON but responded differently to co-occurring DON derivatives. In naturally contaminated maize, immunoassay results reflected the combined presence of DON and co-occurring derivatives, consistent with differences in antibody specificity. An interlaboratory comparison involving multiple grain elevators analyzing identical blinded samples demonstrated substantial between-site variability in reported DON concentrations, with about 16% of results deviating by more than ±20% from the LC-MS/MS reference value. Collectively, these findings show that inconsistent DON test outcomes arise from the combined effects of antibody cross-reactivity and site-specific testing variability, rather than from any unreliability of the analytical methods themselves. This finding highlights the importance of interpreting rapid DON measurements considering these factors.