No abstract

No abstract

An analytical method for determination and confirmation of nine coccidiostatics in eggs is reported. Ethyl acetate is used as extraction solvent, with satisfactory results, and simple automated clean-up is based on gel-permeation chromatography (GPC) . The target compounds are then analysed by liquid chromatography-electrospray ionization-tandem mass spectrometry. The method was validated in-house in accordance with Commission Decision 2002/657/EC. Trueness and precision were determined at four concentrations, and the mean errors obtained were <10 %, with relative standard deviations ranging from 3 to 18 %. For three non-authorized coccidiostatics (clopidol, ethopabate, and ronizadole), decision limit and detection capability were in the ranges 0.12-0.16 and 0.18-0.23 μg kg(-1), respectively. The results obtained prove the suitability of this new analytical method for routine monitoring of these substances in eggs.

Ion suppression in analysis of tetracyclines in feed was studied. The conventional analysis consists of a liquid extraction followed by a clean-up step using solid phase extraction (SPE) technique and analysis of the tetracyclines by liquid chromatography and mass spectrometric detection. Various strategies for extraction and cleanup were tested in the present work, and the effectiveness to decrease the ion suppression on the MS/MS signals was evaluated. Four sample treatment methods were tested with five different feed samples. Extraction solvents tested were McIlvaine buffer and a mixture of McIlvaine buffer dichloromethane (3 : 1). SPE cartridges for cleanup were Oasis HLB, Oasis MCX, and Oasis MAX. The effectiveness of the methods was evaluated in terms of decreasing the ion suppression effect but also of decreasing the variability of ion suppression between samples. The method that provided the most satisfactory results involved a clean-up step based on SPE using mixed-mode cation exchange cartridges (Oasis MCX).