A collaborative study to validate novel field immunoassay kits for rapid mycotoxin detection.

Kits designed to detect ochratoxin A (OA) and T-2 toxin by a membrane-based flow-through enzyme immunoassay were studied collaboratively by screening cereals (wheat, rye, maize and barley) for the presence of these mycotoxins. Sample preparation and test procedure were clearly described in the instruction leaflets included in the kits. A simple methanol-based extraction followed by filtration and dilution steps was prescribed. Reagents were successively pipetted to the membrane of the device, then colour development was evaluated visually. Limits of detection for the ochratoxin A and T-2 toxin tests were 4 and 50 microg kg(-1), respectively. Five laboratories took part in the first stage of this study, and five more joined the second stage. Cereal samples (blank, spiked or inoculated) were shipped with the kits to the participating laboratories, while results obtained were confirmed by high-performance liquid chromatography with fluorescence detection and by gas chromatography-mass spectrometry for ochratoxin A and T-2 toxin, respectively. Some initial difficulties were encountered. In the second stage, four ochratoxin A and four T-2 toxin kits were used by 10 collaborators to analyse 21 cereal samples. For the ochratoxin A kits, the percentage of false positive and false negative results were 2% and 4%, respectively. The results of one T-2 toxin kit were outliers and when excluded, the overall percentage false positive and false negative results were 6% and 3%, respectively.