title: Structural elucidation of sulfaquinoxaline metabolism products and their occurrence in biological samples using high-resolution Orbitrap mass spectrometry.
abstract: Four previously unreported metabolism products of sulfaquinoxaline (SQX), a widely used veterinary medicine, were isolated and analyzed using liquid chromatography coupled to high-resolution Orbitrap mass spectrometry. Metabolites were structurally elucidated, and a fragmentation pathway was proposed. The combination of high-resolution MS(2) spectra, linear ion trap MS(2), in-source collision-induced dissociation (CID) fragmentation, and photolysis were used to analyze SQX and its metabolites. All metabolism products identified showed a similar fragmentation pattern to that of the original drug. Differential product ions were produced at m/z 162 and 253 which contain the radical moiety with more 16 Da units than sulfaquinoxaline. This occurs by a hydroxyl attachment to the quinoxaline moiety. With the exception of two low-intensity compounds, all the mass errors were below 5.0 ppm. The distribution of these metabolites in some animal species are also presented and discussed.
authors.affiliation: Laboratório Nacional Agropecuário, Estrada da Ponta Grossa, 3036, Porto Alegre, Rio Grande do Sul 91780, Brazil.
authors.forename: Rodrigo Barcellos
authors.initials: RB
authors.lastname: Hoff
authors.forename: Leonardo
authors.initials: L
authors.lastname: Meneghini
authors.forename: Tânia Mara
authors.initials: TM
authors.lastname: Pizzolato
authors.forename: Maria do Carmo Ruaro
authors.initials: Mdo C
authors.lastname: Peralba
authors.forename: M Silvia
authors.initials: MS
authors.lastname: Díaz-Cruz
authors.forename: Damià
authors.initials: D
authors.lastname: Barceló
mesh_terms: D000818:Animals; D001711:Biotransformation; D002417:Cattle; D002851:Chromatography, High Pressure Liquid; D017665:Hydroxyl Radical / Q000737:chemistry; D006900:Hydroxylation; D007202:Indicators and Reagents; D008099:Liver / Q000737:chemistry; D013058:Mass Spectrometry; D011200:Poultry; D012756:Sheep; D013428:Sulfaquinoxaline / Q000737:chemistry* / Q000378:metabolism; D014018:Tissue Distribution
chemical_list: D007202:Indicators and Reagents; D017665:Hydroxyl Radical; D013428:Sulfaquinoxaline