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

## TL;DR

This study finds that inconsistent DON test results in maize come from antibody reactions and testing site differences, not the test kits themselves.

## Contribution

The study identifies two specific sources of variability in DON immunoassay results: antibody cross-reactivity and site-specific testing practices.

## Key findings

- Immunoassay kits differ in their response to DON derivatives, affecting measurement accuracy.
- Grain elevator testing sites showed up to 16% deviation in DON measurements compared to a reference method.
- Variability in test results is due to antibody specificity and testing practices, not kit unreliability.

## Abstract

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.