Maduramicin [KLH]

A multi-residue method has been developed and validated for the simultaneous determination of authorized (decoquinate, diclazuril, halofuginone, lasalocid, maduramicin, monensin, narasin, nicarbazin, robenidine, salinomycin and semduramicin) and non-authorized (amprolium, clopidol, ethopabate and toltrazuril) coccidiostats in animal feed. Feed samples were extracted with basic followed by acidified solution in methanol and, after centrifugation, were injected directly into LC-MS/MS system. Detection was performed in selected reaction monitoring mode with both positive and negative electrospray ionization. The time efficient validation experiment has verified the robustness of a method in different types of feed and on two separate LC-MS/MS instruments. The comparison of different quantification methods demonstrated that, against expectations, the standard addition did not prove better in comparison with matrix-matched calibration curve. Although the sample preparation was very easy, the observed matrix effects were not significant for the most part but they could explain the problems with the quantification of some coccidiostats. (C) 2015 Elsevier B.V. All rights reserved.

Drugs that are used as medicines and also as growth promoters in veterinary care are considered as emerging environmental contaminants and in recent years concern about their potential risk to ecosystems and human health has risen. In this paper we used a method based on liquid chromatography/electrospray tandem mass spectrometry to analyze eight coccidiostatic compounds: diclazuril, dinitrocarbanilide (the main metabolite of nicarbazin), robenidine, lasalocid, monensin, salinomycin, maduramicin and nasarin. Multiple-stage mass spectrometry (MSn) based on the precursor ions [M + Na](+) (polyether ionophores), [M + H](+) (robenidine) and [M - H](-) (diclazuril and dinitrocarbanilide) was used to study the fragmentation of these compounds. MS' data and genealogical relationships were used to propose a tentative assignment of the different fragment ions. Loss of water, decarboxylations, ketone beta-cleavages and rearrangement of cyclic ethers and amide groups were some of the fragmentations observed for these compounds. Liquid chromatography with a sub-2 mu m particle size column was coupled to tandem mass spectrometry (LC/MS/MS) allowing the separation of these compounds in less than 7 min. Method detection limits ranging from 11 to 71 ng L-1 and run-to-run values in terms of relative standard deviation (RSD) (up to 12%) were obtained. Copyright (C) 2009 John Wiley & Sons, Ltd.