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.

Intramammary treatment with gentamicin in lactating cows with clinical and subclinical mastitis

“…In Brazil, studies have detected these residues in pasteurized milk, including residues of gentamicin, an antibiotic widely used for intramammary treatment of cows with mastitis (Bando et al 2009, Spisso et al 2010. In many countries, gentamicin is not approved for use in dairy cattle and the extralabel use of this drug is not encouraged.…”

Effect of pasteurization on the residues of tetracyclines in milk

“…When heated or exposed to acidic or highly alkaline environments, tetracyclines are subject to chemical transformation processes, such as isomerization and epimerization (Wang et al 2012). For this reason, when establishing MRLs it is necessary to take into account both the basic compound (tetracycline) and its epimers (the 4-epimer products of TTC, OTC and CTC) (Commission Regulation 37/2010; Spisso et al 2010).…”

Panorama da ocorrência de resíduos de medicamentos veterinários em leite no Brasil

“…Em outra pesquisa, utilizou-se a técnica de CLAE com detecção por fluorescência para análise direta de sulfonamidas [5] . Na determinação de tetraciclinas foram citadas as técnicas cromatográficas CLAE-EM/EM com ionização por Electrospray (ESI) e analisador do tipo triplo quadrupolo para análise direta e como método de confirmação [41] e CLAE com detecção por absorção no ultravioleta para análise de triagem [5,30] .…”

“…Na confirmação de β-lactâmicos por CLAE-EM, foram detectados resíduos de cefapirina nas 6 amostras com resultados acima do LD na análise de triagem [5] . De 14 amostras de leite pasteurizado analisadas no período de 2009/2010 que obtiveram teores acima do LD, todas apresentaram resíduos de oxitetraciclina e em apenas 1 foi detectado também resíduo de tetraciclina [41] .…”