title: Development and validation of an ultra-high performance liquid chromatography tandem mass spectrometry method for quantifying thyreostats in urine without derivatisation.
abstract: Thyreostatic drugs, illegally administrated to livestock for fattening purposes, are banned in the European Union since 1981 (Council Directive 81/602/EC). For monitoring their illegal use, sensitive and specific analytical methods are required. In this study an UHPLC-MS/MS method was described for quantitative analysis of eight thyreostatic drugs in urine, this without a derivatisation step. The sample pretreatment involved a reduction step with dithiothreitol under denaturating conditions at 65 degrees C, followed by liquid-liquid extraction with ethyl acetate. This analytical procedure was subsequently validated according to the EU criteria (2002/657/EC Decision), resulting in decision limits and detection capabilities ranging between 1.1 and 5.5 microg L(-1) and 1.7 and 7.5 microg L(-1), respectively. The method obtained for all, xenobiotic thyreostats, a precision (relative standard deviation) lower than 15.5%, and the linearity ranged between 0.982 and 0.999. The performance characteristics fulfill not only the requirements of the EU regarding the provisional minimum required performance limit (100 microg L(-1)), but also the recommended concentration fixed at 10 microg L(-1) in urine set by the Community of Reference Laboratories. Future experiments applying this method should provide the answer to the alleged endogenous status of thiouracil.
authors.affiliation: Ghent University, Faculty of Veterinary Medicine, Research Group of Veterinary Public Health and Zoonoses, Laboratory of Chemical Analysis, Salisburylaan 133, B-9820 Merelbeke, Belgium. Julie.Vandenbussche@Ugent.be
authors.forename: J
authors.initials: J
authors.lastname: Vanden Bussche
authors.forename: L
authors.initials: L
authors.lastname: Vanhaecke
authors.forename: Y
authors.initials: Y
authors.lastname: Deceuninck
authors.forename: K
authors.initials: K
authors.lastname: Verheyden
authors.forename: K
authors.initials: K
authors.lastname: Wille
authors.forename: K
authors.initials: K
authors.lastname: Bekaert
authors.forename: B
authors.initials: B
authors.lastname: Le Bizec
authors.forename: H F
authors.initials: HF
authors.lastname: De Brabander
mesh_terms: D000818:Animals; D013956:Antithyroid Agents / Q000652:urine*; D002417:Cattle; D002851:Chromatography, High Pressure Liquid / Q000379:methods* / Q000662:veterinary; D012756:Sheep; D013552:Swine; D053719:Tandem Mass Spectrometry / Q000379:methods* / Q000662:veterinary; D013889:Thiouracil / Q000652:urine
chemical_list: D013956:Antithyroid Agents; D013889:Thiouracil