LC/MS confirmation of ionophores in animal feeds

J AOAC Int. 2001 May-Jun;84(3):640-7.

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.

MeSH terms

  • Animal Feed / analysis*
  • Chromatography, Liquid / methods*
  • Food, Fortified
  • Ionophores / analysis*
  • Lasalocid / analysis
  • Lasalocid / chemistry
  • Mass Spectrometry / methods*
  • Monensin / analysis
  • Pyrans / analysis
  • Pyrans / chemistry

Substances

  • Ionophores
  • Pyrans
  • salinomycin
  • Monensin
  • narasin
  • Lasalocid