Identification of Mequindox and Its Metabolites by High Performance Liquid Chromatography Combined with Ion Trap-Time of Flight-Mass Spectrometry / 分析化学

ABSTRACT

The chemical structures of mequindox related metabolites in chicken plasma had been investigated using high performance liquid chromatography combined with linear ion trap quadrupole(LC-ESI/LTQ) and high performance liquid chromatography combined with ion trap-time of flight-mass spectrometry (LC-ESI/IT-TOF).Samples were separated by Hypersil BDS C_(18) and symmetry Shield columns, respectively, and 0.01% formic acid aqueous(A) and methanol(B) were used as mobile phase with gradient elution.Electros pray ionization mass spectrometric(ESI) source was used and operated in positive ion mode.When chickens were orally administered with mequindox at dosage of 20 mg/kg, blood samples were collected from the brachi al vein.Mequindox and its metabolites were extracted by the mixture of acetonitrile and acetoacetate (32, V/V).After solvent evaporated, the residue was dissolved in 30% methanol aqueous and the solution was detected by LC/IT-TOF MS and LC-ESI/LTQ.The molecule weight from LC-ESI/IT-TOF was analyzed by software Shimadzu's Composition and the mass chromatogram from LC-ESI/LTQ was analyzed by software Xcalibur 2.0.7.According to the molecular weight and MS~n data, referring the metabolic reaction rules, five chemical structures of mequindox related metabolites in chicken plasma were identified.Metabolites (M1-M4) were synthesized to verify the structure of metabolites.The metabolites are 3-methyl-2-(1-hydroxy) ethyl-qui-noxaline-N~1,N~4-dioxide(Ml), 3-methyl-2-(1-hydroxy) ethyl-quinoxaline-N~4-oxide(M2), 3-methyl-2-acetyl-quinoxaline-N~4-oxide, 3-methyl-2-acetyl-quinoxaline (M4), 3-hydroxymethyl-2-(1-hydroxy) ethyl-quinoxa-line-N~1,N~4-dioxide (M5).