Assessment of oxytetracycline residue by microbial assay and high performance thin layer chromatography in milk

Abstract

Aim: This study aims to detect oxytetracycline residue in milk by a simple microbial screening and chromatographic method.Methodology: A total of 200 milk samples were collected from organized dairy farms in and around Chennai. Milk samples were screened for the presence of oxytetracycline antibiotic residues by microbial assay using Bacillus subtilis MTCC 121T and antibiotic residue positive samples and were confirmed by High Performance Thin Layer Chromatography.Results: The results revealed that 19 milk samples were positive for oxytetracycline residue in milk by microbial assay and was confirmed by High Performance thin layer chromatography with average concentration of 139.25 µg/kg and 78.59 µg/kg in cow and buffalo milk respectively.Conclusion: The study infers that the microbial screening method is a simple and economical method that can be used to detect antibiotic residues in foods of animal origin.