title: Overcoming matrix effects in electrospray: quantitation of β-agonists in complex matrices by isotope dilution liquid chromatography-mass spectrometry using singly (13)C-labeled analogues.
abstract: In this work, the implementation of isotope dilution mass spectrometry (IDMS) using minimal labeling and isotope pattern deconvolution (IPD) is evaluated as a strategy for the minimization of matrix effects during trace determination of β2-agonists in complex matrices by liquid chromatography electrospray ionization mass spectrometry (LC-ESI-MS). First, the parameters affecting the measurement of isotopic composition of organic compounds by liquid chromatography electrospray ionization high resolution mass spectrometry with a time-of-flight analyzer were evaluated using as a case of study three different β2-agonists: clenbuterol, clenproperol and brombuterol. Then, a calibration graph-free IDMS methodology was evaluated in order to overcome matrix effects in LC-ESI-MS in complex samples. In this procedure singly (13)C-labeled analogues of clenbuterol, clenproperol and brombuterol were employed in combination with IPD. Using this approach accurate and precise results were obtained in the simultaneous quantification of β2-agonists in human urine and bovine liver, even at the sub ngg(-1) and particularly in spite of the previously reported matrix effects. Recovery rates in the range of 97-114% in fortified human urine and from 95% to 111% in fortified bovine liver were obtained with RSD (%) of independent recovery experiments always lower than 6%. These results demonstrate that the proposed methodology based on the use of (13)C1-labeled standards and IPD is a reliable approach for accurate LC-MS quantitation of small molecules and compatible with full-scan high-resolution mass spectrometry.
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.forename: Juan C
authors.initials: JC
authors.lastname: Domínguez-Romero
authors.forename: Juan F
authors.initials: JF
authors.lastname: García-Reyes
authors.forename: Pablo
authors.initials: P
authors.lastname: Rodríguez-González
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Centineo
authors.forename: J Ignacio
authors.initials: JI
authors.lastname: García Alonso
authors.forename: Antonio
authors.initials: A
authors.lastname: Molina-Díaz
mesh_terms: D000318:Adrenergic beta-Agonists / Q000032:analysis* / Q000737:chemistry / Q000652:urine; D000818:Animals; D002247:Carbon Isotopes / Q000737:chemistry; D002417:Cattle; D002853:Chromatography, Liquid / Q000379:methods*; D004983:Ethanolamines / Q000032:analysis* / Q000737:chemistry / Q000652:urine; D005260:Female; D006801:Humans; D007553:Isotope Labeling / Q000379:methods; D057230:Limit of Detection; D016014:Linear Models; D008099:Liver / Q000737:chemistry; D008297:Male; D015203:Reproducibility of Results; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods*
chemical_list: D000318:Adrenergic beta-Agonists; D002247:Carbon Isotopes; D004983:Ethanolamines