High-performance liquid chromatography determination of Zn-bacitracin in animal feed by post-column derivatization and fluorescence detection

A sensitive and selective method is presented for the determination of Zn-Bacitracin in adulterated animal feed by reversed-phase ion-pair high-performance liquid chromatography and post-column derivatization with o-phthalaldehyde prior to fluorescence detection. The calibration function was estimated to be between 8.0 and 65.0 mg l−1 of Zn-BC. The detection and quantification limits of the chromatographic method were 2.5 and 7.5 mg l−1, respectively. Using the extraction procedure of Zn-Bacitracin from the feedstuff that we recently proposed and applying this new chromatographic method, it was possible to detect this antibiotic at levels below 5 mg kg−1 in different kinds of feedstuffs with a standard deviation less than 6.0%.