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Multiclass method for antimicrobial analysis in animal feeds by liquid chromatography–tandem mass spectrometry

Borràs, S., Companyó, R., Guiteras, J., Bosch, J., Medina, M., Termes, S.
Analytical and bioanalytical chemistry 2013 v.405 no.26 pp. 8475-8486
acetonitrile, anti-infective agents, antibiotic residues, cattle feeds, feed contamination, ionization, liquid chromatography, methanol, poultry, solid phase extraction, swine, tandem mass spectrometry
A rapid multiclass method that covers 50 antimicrobials from 13 different families in animal feeds was developed. Samples were extracted using a mixture of methanol, acetonitrile and a McIlvaine buffer combined with sonication. Feed extracts were simply diluted prior to injection, since the clean-up strategies that were tested, based on either solid-phase extraction or dispersive solid-phase extraction, were ineffective at minimizing matrix-related signal suppression/enhancement. Analysis was carried out by liquid chromatography coupled to tandem mass spectrometry using an electrospray ionization source operating in positive and negative modes. For the quantification, matrix-fortified standard calibration curves were used to compensate for matrix effects and losses in sample preparation. The method was validated in-house in pig, poultry and cattle feed matrices and showed satisfactory performance characteristics. Thus, the proposed approach was suitable for application in a routine high-throughput laboratory for the official control of feeds.