This International Standard specifies a qualitative method for the determination of zearalenone in animal feeding stuffs and, in particular, in maize. This method is for screening purposes only. The limit of determination of zearalenone is approximately 50 μg/kg. NOTE Although sorghum gives interfering fluorescent spots identical to those of zearalenone, the method is still applicable to this feed because the Rf values are different after development of the chromatogram in the second direction. These spots are not developed by the specified confirmation technique.