title: LC/MS confirmation of ionophores in animal feeds.
abstract: A liquid chromatographic/mass spectrometric (LC/MS) electrospray confirmation method has been developed to confirm 4 ionophores (monensin, lasalocid, salinomycin, and narasin) in a variety of animal feeds using a single quadrupole mass spectrometer. The sodium ions of these compounds are dominant in the electrospray mass spectrum. Using optimized "in-source" collision induced dissociation, characteristic fragment ions seen previously using MS/MS can be observed. The drugs were extracted from the feed matrix using hexane-ethyl acetate and isolated using a silica solid-phase extraction cartridge. These ionophores were confirmed in both medicated feeds and nonmedicated feeds fortified with these drugs at the 1-50 ppm level. In addition, this method was used to confirm residues of monensin in a nonmedicated feed that was collected from a feed mill immediately after the production of a similar feed that was medicated with high levels of monensin.
authors: US Food and Drug Administration, Animal Drug Research Center and Denver District Laboratory, CO 80225, USA.
authors: S B
authors: SB
authors: Turnipseed
authors: J E
authors: JE
authors: Roybal
authors: A P
authors: AP
authors: Pfenning
authors: S A
authors: SA
authors: Gonzales
authors: J A
authors: JA
authors: Hurlbut
authors: M R
authors: MR
authors: Madson
mesh_terms: D000821:Animal Feed / Q000032:analysis*; D002853:Chromatography, Liquid / Q000379:methods*; D005527:Food, Fortified; D007476:Ionophores / Q000032:analysis*; D007832:Lasalocid / Q000032:analysis / Q000737:chemistry; D013058:Mass Spectrometry / Q000379:methods*; D008985:Monensin / Q000032:analysis; D011714:Pyrans / Q000032:analysis / Q000737:chemistry; D000095662:Polyether Polyketides
chemical_list: D007476:Ionophores; D007832:Lasalocid; D008985:Monensin; D011714:Pyrans; C010327:salinomycin; D000095662:Polyether Polyketides; C013612:narasin