Abstract
An improved liquid chromatographic‐mass spectrometry method for the simultaneous determination of four anticoccidial drugs in feed is described. Samples were homogenized with methanol‐acetone‐tetrahydrofuran. The samples were mixed and centrifuged. After centrifugation, 100 µL supernatant was extracted with hexane, evaporated to dryness, diluted with acetonitrile‐water, filtered through a Spin‐X micro‐centrifuge tube, and injected into the LC/MS. The calibration curves were linear in the investigated areas. The limit of quantification varied from 0.2 to 0.6 µg/g. The method described was used for the determination of anticoccidial agents in medicated feeds and to examine the degree of anticoccidials contamination of unmedicated feeds (carry over).