title: Quantitative analysis of tylosin in eggs by high performance liquid chromatography with electrospray ionization tandem mass spectrometry: residue depletion kinetics after administration via feed and drinking water in laying hens.
abstract: Maximum residue limits (MRLs) have been established by the European Union when tylosin is used therapeutically. They are fixed at 200 microg/kg for eggs. A highly sensitive and selective quantitative liquid chromatography electrospray ionization tandem mass spectrometry (LC/ESI/MS/MS) method suitable for monitoring tylosin residues in eggs to determine its depletion kinetics was developed and validated. For sample pretreatment all samples were liquid-liquid extracted with citrate buffer (pH 5.0) and acetonitrile. Liquid chromatographic separation was carried out on a reversed phase C18 column employing a 0.5% formic acid/acetonitrile gradient system. The tylosin recovery in eggs at a concentration range from 1.0-400 microg/kg was >82% with relative standard deviations between 1.5 and 11.0%. In two experimental studies administrating tylosin via feed (final dosage: 1.5 g/kg) or drinking water (final dosage: 0.5 g/L), no residues above the MRL were found during and after treatment. Moreover, all samples were well below the actual MRL of 200 microg/kg. Therefore, our residue data suggest that a withholding period for eggs is not required when laying hens are treated with tylosin in recommended dosages via feed or drinking water.
  
  
  BACKGROUND
  Tylosin; residue; depletion; laying hen; withholding period; mass spectrometry.
authors.affiliation: Institute for Food Toxicology, University of Veterinary Medicine Hannover, Foundation, Bischofsholer Damm 15, D-30173 Hannover, Germany. Gerd.Hamscher@tiho-hannover.de
authors.forename: Gerd
authors.initials: G
authors.lastname: Hamscher
authors.forename: Sasithorn
authors.initials: S
authors.lastname: Limsuwan
authors.forename: Natthasit
authors.initials: N
authors.lastname: Tansakul
authors.forename: Manfred
authors.initials: M
authors.lastname: Kietzmann
mesh_terms: D000821:Animal Feed; D000818:Animals; D000900:Anti-Bacterial Agents / Q000008:administration & dosage / Q000737:chemistry*; D002645:Chickens; D002851:Chromatography, High Pressure Liquid; D004350:Drug Residues / Q000737:chemistry*; D004531:Eggs / Q000032:analysis*; D010058:Oviposition; D021241:Spectrometry, Mass, Electrospray Ionization; D015645:Tylosin / Q000008:administration & dosage / Q000737:chemistry*; D014867:Water
chemical_list: D000900:Anti-Bacterial Agents; D014867:Water; D015645:Tylosin