Determination of Polar Veterinary Drugs and Melamine in Feeds: Method Using Ion-Pair Reversed-Phase or Hydrophilic Interaction Liquid Chromatography Coupled to Tandem Mass Spectrometry

This protocol specifies a LC-ESI-MS/MS method for the quantification of the polar veterinary drugs spectinomycin, zilpaterol, halquinol (a combination of chemical species: 5,7-dichloroquinolin-8-ol, 5-chloroquinolin-8-ol, and 7-chloroquinolin-8-ol, in variable proportions depending on the drug supplier) and the adulterant/contaminant melamine in several feeds intended for pets and production animals. The analytes extraction is carried out in acidic environment that results in a straightforward and efficient procedure. This method proves that HILIC and reversed-phase liquid chromatography with modified chemical equilibrium are proper analytical strategies to separate those analytes before their quantitation by tandem mass spectrometry using internal standard calibration. This multipurpose method can be performed in a short time of analysis, increasing sample throughput in feed control laboratories.