Determination of Tetracyclines in Animal Feeds in the Presence of Other Drugs by Thin-Layer Chromatography and Microbiological Method

Abstract

Abstract This method was developed to separate, detect, and quantitate oxytetracycline (OTC) or chlortetracycline hydrochloride (CTC HCI) in animal feeds in thepresence of 11 otherdrugs: 3 nitrofurans, 2 macrolideantibiotics,3 sulfonamides, 2 coccidiostatics, and 1 antibacterial growth promoter. OTC or CTC HCI was separated from coexisting drugs and detected by thin-layer chromatography, then quantitated microbiologically by the agar diffusion method. Analysis of 125 experimental animal feed samples fortified at 5 levels (7.5-400 ppm) with OTC or CTC HCI and at 1 level (50 ppm) with the rest of the drugs, respectively, gave a limit of quantitation of 1.25 or 0.625 ppm, a recovery of 90.6 or 92.9%, and a coefficient of variation of 2.9-6.1 or 2.3-4.4%.