Determination Of Quinocetone In Feed And Identification Of Quinocetone And Its Metabolists In Chicken Feces

Since 1940s, Quinoxaline 1,4-dioxides are known as potent antibacterial agents, and subtherapeutic levels have been used to promote growth and improve efficiency of feed conversion in animal feed. Olaquindox and carbadox are the well-known quinoxaline 1,4-dioxides, but they have been banned or strictly limited for use in food-producing animals because of their toxicities. As a new member of quinoxaline 1,4-dioxides, Quinocetone (3-methyl-2-cinnamicacyl-quinoxaline-l,4-dioxide) is more effective for growth promotion and less toxic in young swine and chicken. It was developed by Lanzhou Institute of Animal & Pharmaceutics Science(Lanzhou, People's Republic of China) in 1990s.The content in this paper is included as follow: analysis of quinocetone in feed, synthesis of metabolites of quinocetone and identification of quinocetone and its metabolites in chicken feces.A high performance liquid chromatography method was developed to determine the amount of quinoacetone in feed. The feed sample was extracted with acetonitrile. Seperation of the drug was obtained using a C₁₈ gel column with acetonitrile /water (45:55 v/v) as mobile phase. The detection wavelength was 380 nm . A good linear response was obtained for quinoacetone standard from 0.04 to 0.6μg and the correlation coefficient was 0.9999. The average recoveries of quinoactone in three different levels were 89.42%, 96.20% and 98.83%.In order to confirm the quinocetone and its metabolites in chicken feces. We synthesized the several major metabolites of quinocetone and analyzed them by IR, UV, 1HNMR and ESI-MS.High performance liquid chromatography coupled with electrospray ionization tandem mass spectrometry (HPLC-MS/MS) was applied to identify the quinocetone metabolites in chicken feces. Three female and three male chickens aged one month were administered orally at a dose of 40g/kg . Feces samples were collected in the 24 hour period after dosing the chickens.Confirmation of several metabolites structures was achieved by direct comparison of their LC/MS/MS data to those obtained from synthetic metabolite standards. The results showed that the feces metabolites were identified as desoxyquinocetone, 1-monoxyquinocetone , 4-monoxyquinocetone and 3-methyl-quinoxaline-2-carboxylic acid, in addition to the unchanged drug.