title: Identification of the related substances of tilmicosin by liquid chromatography/ion trap mass spectrometry.
abstract: Structures of seven impurities of the veterinary drug tilmicosin have been elucidated by multiple fragmentation with ion trap tandem mass spectrometry. All related compounds possess the main lactone ring of tilmicosin. The differences in their structures are due to the hydroxyl, mycaminose, 3,5-dimethylpiperidine and mycinose groups connected to C(3), C(5), C(6), C(14) of the lactone ring, respectively. The following compounds of the impurity profile of tilmicosin were identified: B - tilmicosin with a hydroxyl group at C(3); C - tilmicosin without a methyl group at the N-atom connected to C(3) of the mycaminose ring; D - tilmicosin with a hydroxyl group at C(6) of the mycaminose ring; E - tilmicosin with a methoxy group at C(3), F - desmicosin; G - 20-dihydrodesmicosin; and H - tilmicosin without a mycaminose ring. Isomers of the compounds B, C, D, E and H were identified by their mass chromatograms and retention times. The concentrations of the impurities varied in the range of 0.1% to 2.9%.
authors.affiliation: CLVCE, Iskarsko Shousse 5, Sofia 1528, Bulgaria. s_georgi@hotmail.com
authors.forename: Georgi
authors.initials: G
authors.lastname: Stoev
authors.forename: Valeri
authors.initials: V
authors.lastname: Nazarov
mesh_terms: D000900:Anti-Bacterial Agents / Q000032:analysis / Q000737:chemistry*; D002853:Chromatography, Liquid / Q000295:instrumentation / Q000379:methods*; D004340:Drug Contamination; D013058:Mass Spectrometry / Q000379:methods*; D008958:Models, Molecular; D021241:Spectrometry, Mass, Electrospray Ionization; D015645:Tylosin / Q000031:analogs & derivatives* / Q000032:analysis / Q000737:chemistry; D019155:Veterinary Drugs / Q000032:analysis / Q000737:chemistry*
chemical_list: D000900:Anti-Bacterial Agents; D019155:Veterinary Drugs; C052319:tilmicosin; D015645:Tylosin