title: Simultaneous determination of seven β2-agonists in human and bovine urine by isotope dilution liquid chromatography-tandem mass spectrometry using compound-specific minimally13C-labelled analogues.
abstract: Seven β2-agonist (clenproperol, clenbuterol, salbutamol, bronbuterol, ractopamine, clenpenterol and clencyclohexerol) were determined simultaneously in human and bovine urine by isotope dilution LC-ESI-MS/MS in a triple quadrupole instrument. The method is based on the application of multiple linear regression in combination with compound-specific minimally13C-labelled analogues. Additionally, the increase of the bandpass of the first quadrupole during the selected reaction monitoring (SRM) measurement procedure allowed the simultaneous quantification of the seven compounds at sub ngg-1levels in a single chromatogram without resorting to a methodological calibration graph. Recovery values at concentration levels between 5.0 and 0.05ngg-1ranged from 95 to 110% in fortified bovine urine and from 91 to 108% in human urine, with relative standard deviations lower than 5% except for salbutamol and ractopamine. The proposed methodology was validated by analyzing the certified reference material BCR-503 (lyophilized bovine urine) certified for clenbuterol and salbutamol. The limits of detection (LOD) for a sample volume of 10mL of both human and bovine urine was found to be lower than 0.012ngg-1for all compounds, except to salbutamol in bovine urine which was of 0.029ngg-1. The use of compound-specific isotopically labelled analogues minimally labelled in13C minimized the occurrence of isotope effects and corrected for matrix effects during ESI ionization and can be efficiently applied for the quantification of ultra-trace concentrations of β2-agonists in human and bovine urine.
authors.affiliation: Department of Physical and Analytical Chemistry, Faculty of Chemistry, University of Oviedo, Julián Clavería 8, 33006 Oviedo, Spain.
authors.forename: Ana
authors.initials: A
authors.lastname: González-Antuña
authors.affiliation: Department of Physical and Analytical Chemistry, Faculty of Chemistry, University of Oviedo, Julián Clavería 8, 33006 Oviedo, Spain. Electronic address: rodriguezpablo@uniovi.es.
authors.forename: Pablo
authors.initials: P
authors.lastname: Rodríguez-González
authors.affiliation: ISC-Science, Innovative Solutions in Chemistry, S.L., Edificio Científico-Tecnológico, Campus de "El Cristo", 33006 Oviedo, Spain.
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Centineo
authors.affiliation: Department of Physical and Analytical Chemistry, Faculty of Chemistry, University of Oviedo, Julián Clavería 8, 33006 Oviedo, Spain.
authors.forename: J Ignacio
authors.initials: JI
authors.lastname: García Alonso
keywords: Isotope dilution; Liquid chromatography; Matrix effects; Minimal labeling; Selected reaction monitoring; Tandem mass spectrometry