Development and validation of a multiresidue liquid chromatography/tandem mass spectrometry method for 11 coccidiostats in feed.

A confirmatory method for the determination of 11 regulated coccidiostats including the ionophore antibiotics lasalocid, maduramicin, monensin, narasin, salinomycin, and semduramicin and the chemical coccidiostats decoquinate, diclazuril, halofuginone, nicarbazin, and robenidine in animal feed was developed and validated. The procedure was intended for the identification and quantification of the coccidiostats at concentrations relating both to the unintentional carryover as stated in Regulation 574/2011 and to the authorized levels in target feed. The analytes were determined by LC/MS/MS in the positive or negative electrospray ionization mode. The method performance characteristics were estimated in the relevant application field from 0.003 to 200 mg/kg. Validation criteria of linearity, specificity, trueness, precision, LOD, and LOQ along with measurement uncertainty were estimated for all analytes. Absolute and relative matrix effects were also studied. The results proved that the method performance was satisfactory, and it was successfully applied to carryover control by analyzing 165 feed samples collected within regulatory monitoring plans. Finally, since the carryover phenomenon in feed may result in the presence of residues in food products of animal origin, a survey has been carried out on the occurrence of coccidiostats in 167 eggs and animal muscles.

Development and validation of a multi-residue liquid chromatography-tandem mass spectrometry confirmatory method for eleven coccidiostats in eggs.

A confirmatory method for the determination of residues of eleven coccidiostats including ionophore antibiotics: lasalocid, maduramycin, monensin, narasin, salinomycin, semduramycin and chemical coccidiostats: decoquinate, diclazuril, halofuginone, nicarbazin and robenidine in poultry eggs was developed and validated. The sample was extracted with acetonitrile, defatted with hexane and cleaned-up on a silica SPE cartridge. The analytes were identified and quantified by liquid chromatography-tandem mass spectrometry (LC-MS/MS). The method performance characteristics required by Commission Decision 2002/657/EC were estimated adopting a more flexible and simple validation design. In this alternative approach the experimental study focuses on a larger dynamic range with progressively increasing validation levels. Each of them presents equal concentrations of all the analytes. On the contrary the classical Decision plan investigates a restricted concentration range necessarily different for each analyte being determined by the individual permitted limit (0.5-1.5 times the permitted limit). As a consequence each validation level involves the simultaneous fortification with complex mixtures containing different concentrations of each analyte. Adopting this alternative strategy the validation of several substances with significantly different permitted limits is considerably simplified and a deeper knowledge of the method is achieved. The results proved that the method enables the confirmation of regulated coccidiostats in eggs at the levels required in the official control of residues (CCα in the range of 2.2-174 µg kg(-1), depending on the coccidiostat). The repeatability (CV(r) in the range of 1.1-19%) and within-laboratory reproducibility (CV(Rw) in the range of 1.8-30%) are also acceptable. The procedure was successfully verified in the proficiency test and implemented in the national residue control plan.