Disposition and Residues of Marbofloxacin in Eggs of Laying Hens

Marbofloxacin belongs to the group of fluoroquinolones, used exclusively in domestic animals. This study was carried out with the purpose of studying the temporal disposition of marbofloxacin in edible compartments of the egg after administration of 1, 52 mg/kg of marbofloxacin in drinking water for 11 consecutive days in hens in posture peak and average weight of 1,91±0,25 kg. Birds were housed in individual cages under controlled light conditions, ambient temperature, relative humidity, water and balanced feed ad libitum. After the administration, eggs were collected daily and immediately separated into albumen and yolk, identified per bird/day and stored at-20°C until analysis. The preparative assay consisted in extraction of the analyte using 200 mg of yolk or albumen, as appropriate, in deionized water, homogenizing solution and enrofloxacin solution as internal standard. Separation and quantification were performed by HPLC by reverse phase isocratic elution with fluorescence detector, mobile phase composed of water, acetonitrile and triethylamine adjusted to pH 3. According to the peak areas of known concentrations, the concentrations of the test samples were calculated by simple linear regression. The established marbofloxacin levels are higher and more persistent in the yolk than in albumen, reaching 8 and 9 days, respectively. The disposition characteristics observed with marbofloxacin are compatible with the physico-chemical properties of the antimicrobial with the respective compartments of the egg and the time required for its formation. Data obtained from marbofloxacin depletion in egg compartments were analyzed using the EMEA WT 1.4 software and conjecturing a rigorous MRL (0,001 µg/kg), a withdrawal period of 13 and 17 days was estimated, for albumen and yolk, respectively.