title: Fragmentation study of salinomycin and monensin A antibiotics using electrospray quadrupole time-of-flight mass spectrometry.
abstract: The fragmentation pathways of two selected ionophore antibiotics, salinomycin and monensin A, were studied using electrospray (ES) orthogonal acceleration quadrupole time-of-flight mass spectrometry in positive-ion mode. The identity of fragment ions was determined by accurate-mass measurements. In ES mass spectra, ion signals of relatively high intensity were observed for [M+Na](+) and [M-H+2Na](+) for each antibiotic. Each of the ion species [M+Na](+) and [M-H+2Na](+) for salinomycin and [M-H+2Na](+) for monensin A were isolated in turn and subjected to fragmentation. In the fragmentation of [M+Na](+) and [M-H+2Na](+) from salinomycin, only Cbond;C single bond cleavage and dehydration were observed. Product ion mass spectra obtained from [M-H+2Na](+) of monensin A showed that ether ring opening, Cbond;C single bond cleavage and dehydration fragmentations had occurred. Fragment ions containing two sodium atoms were observed in the product ion mass spectrum of [M-H+2Na](+) from salinomycin, but not from monensin A. Both type A (containing the terminal carboxyl group) and type F (containing the terminal hydroxyl group) fragment ions were observed in the product ion mass spectra of sodium adduct ions of salinomycin and monensin A.
authors.affiliation: Water Quality Centre, Trent University, Peterborough, ON K9J 7B8, Canada.
authors.forename: Xiu-Sheng
authors.initials: XS
authors.lastname: Miao
authors.forename: Raymond E
authors.initials: RE
authors.lastname: March
authors.forename: Chris D
authors.initials: CD
authors.lastname: Metcalfe
mesh_terms: D000900:Anti-Bacterial Agents / Q000737:chemistry*; D013058:Mass Spectrometry / Q000379:methods*; D015394:Molecular Structure; D008970:Molecular Weight; D008985:Monensin / Q000737:chemistry*; D011714:Pyrans / Q000737:chemistry*; D000095662:Polyether Polyketides
chemical_list: D000900:Anti-Bacterial Agents; D008985:Monensin; D011714:Pyrans; C010327:salinomycin; D000095662:Polyether Polyketides