title: Quantitative determination of corticosteroids in bovine milk using mixed-mode polymeric strong cation exchange solid-phase extraction and liquid chromatography-tandem mass spectrometry.
abstract: A new method was developed to identify and quantify corticosteroids (prednisolone, methylprednisone, flumetasone, dexamethasone, and methylprednisolone) in raw bovine milk by liquid chromatography-tandem mass spectrometry (LC-MS/MS) utilizing mixed-mode polymeric strong cation exchange and reversed-phase (MCX) solid-phase extraction (SPE) to reduce ion effects in a multimode ion (MMI) source. The main advantage of this method over other commonly used methods includes the use of a single SPE cartridge with a low volume for sample preparation and fast separation on the HPLC system with reduced ion suppression. This study is the first to report the determination of methylprednisone, a metabolite of methylprednisolone, in bovine milk. This method was validated in accordance with the European Union (EU) Commission Decision 2002/657/EC. The recoveries vary between 90% and 105%. The within-laboratory reproducibility (precision) is less than 30%. The decision limits and detection capabilities were calculated along with LODs, which ranged from 0.02 to 0.07 microg/kg. The method was further enhanced by its successful adaptation to other LC-MS/MS systems equipped with the newly developed ion source, Agilent Jet Stream (AJS). After optimization of the AJS ion source and MS parameters, even lower LOD values were achieved (0.001-0.006 microg/kg) for the corticosteroids. Analytical results obtained with the AJS were characterized by an enhanced area response and similar noise level comparable to those obtained with conventional orthogonal atmospheric ionization (API).
authors.affiliation: Central Agricultural Office Food and Feed Safety Directorate, Food Toxicology National Reference Laboratory, Mester utca 81, Budapest 1095, Hungary. adam.tolgyesi@t-online.hu
authors.forename: Adám
authors.initials: A
authors.lastname: Tölgyesi
authors.forename: László
authors.initials: L
authors.lastname: Tölgyesi
authors.forename: Virender K
authors.initials: VK
authors.lastname: Sharma
authors.forename: Mary
authors.initials: M
authors.lastname: Sohn
authors.forename: Jeno
authors.initials: J
authors.lastname: Fekete
mesh_terms: D000305:Adrenal Cortex Hormones / Q000032:analysis*; D000818:Animals; D002417:Cattle; D002853:Chromatography, Liquid / Q000379:methods*; D057230:Limit of Detection; D008892:Milk / Q000737:chemistry*; D015203:Reproducibility of Results; D052616:Solid Phase Extraction / Q000379:methods*; D053719:Tandem Mass Spectrometry / Q000379:methods*
chemical_list: D000305:Adrenal Cortex Hormones