Establishment And Application Of Detection Methods For Quinoxalines And Their Metabolites

As an antibacterial growth promoters,quinoxalines are usually being feed additives and therapeutic drugs in aquaculture.Some related studies show that quinoxalines are toxic in different way.Nonstandard use will not only affect the normal growth of animals,but also may be harmful to human.Therefore,it is significant to establish a rapid,simple,sensitive method to detect veterinary drugs of multi-residue.The detection methods of quinoxalines and the major metabolities in edible part of aquatic products and fishery inputs were studied in this thesis.1.A method of determinating quinoxalines and the major metabolites residues in fishery input by UPLC-MS/MS was established.The pretreatment methods of quinoxalines and the main metabolites in feed were tested and optimized through comparative experiments.The results showed that it was the best way to extract the samples that using acetonitrile-ethyl acetate(1:1,v/v)and 1 mol/L hydrochloric acid solution,then the analyte which dissolved in the aqueous phase was reextracted by ethyl acetate and purified by the Oasis PRiME HLB SPE cartridge.The solution was dried by nitrogen,redissolved with 1 mL mobile phase and filtered with 0.22 ?m membrane before analysis.The conditions of chromatography-mass spectrometry were optimized.The samples were analyzed with gradient elution,ESI+ scanning mode and quantified by matrix matching standard curve and internal standard method.The results showed that the recovery was 69.5%~96.1%,RSD was 3.2%~9.7% and the correlation coefficient(r)was higher than 0.99.Pharmaceutical fishery inputs can be dissolved and diluted by mobile phase before detection.The method can be used for the rapid detection of quinoxalines and the major metabolites in fishery inputs.2.A method of determinating quinoxalines and the major metabolites residues in aquatic product by UPLC-MS/MS was established.This chapter explores the pretreatment of quinoxalines and the major metabolites in edible tissues of aquatic products.The results showed that it was the best way to extract the samples that using acetonitrile-ethyl acetate(1:1,v/v)and 1 mol/L hydrochloric acid solution.The extraction was degreased with hexane which was saturated by acetonitrile,then the analyte which dissolved in the aqueous phase was reextracted by ethyl acetate and purified by the Oasis PRiME HLB SPE cartridge.The solution was dried by nitrogen,redissolved with 1 mL mobile phase and filtered with 0.22 ?m membrane before analysis.The samples were analyzed with gradient elution,ESI+ scanning mode and quantified by matrix matching standard curve and internal standard method.The results showed that the recovery was 64.4%~102.2%,RSD was 3.2%~10.2% and the correlation coefficient(r)was higher than 0.99.The method can be used for the rapid detection of quinoxalines and the major metabolites in aquatic products.3.The actual samples were detected by the new method.The aquatic products and fishery inputs from nine cities in Guangdong province were detected by this method and positive samples were discovered.The detection rate of fish was 5.9%(QCA),feed was 10.5%(MEQ)and pharmic fishery inputs was 2.4%(MEQ).The result show that the method can be applied to the actual detection of quinoxalines and the metabolites in aquatic products and fishery inputs.