Pilot survey of commercial pasteurized milk consumed in the metropolitan area of Rio de Janeiro, Brazil, for tetracyclines residues, including the 4-epimers of oxytetracycline, tetracycline and chlortetracycline

Abstract

This pilot survey aimed to assess the occurrence of tetracyclines and the 4-epimers of oxytetracycline, tetracycline and chlortetracycline in commercial pasteurized milks sold in the metropolitan area of Rio de Janeiro, Brazil, between October 2009 and March 2010. A liquid chromatography–tandem mass spectrometry (LC–MS/MS) method, developed and validated in our laboratory, was used. All 100 analyzed samples were compliant, but 14 contained oxytetracycline in concentrations ranging from the method limit of detection (3.7 µg l^–1) to the method limit of quantification (12.2 µg l^–1). One sample contained oxytetracycline and tetracycline simultaneously (at a concentration slightly higher than method limit of quantification, 7.0 µg l^–1). The presence of 4-epioxytetracycline and 4-epitetracycline in contaminated samples with the parent drugs could not be confirmed as traces were detected only in the quantification MRM transition. No other tetracyclines were detected.

Keywords:

• milk
• veterinary drug residues, antibiotics, oxytetracyclin, tetracycline

Acknowledgements

The authors acknowledge the financial support from Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) and Financiadora de Estudos e Projetos (FINEP).