1. Clin Biochem. 2015 May;48(7-8):542-5. doi: 10.1016/j.clinbiochem.2015.02.006. Epub 2015 Feb 21. Validation of a HPLC-MS/MS assay for the determination of total and unbound concentration of temocillin in human serum. Ngougni Pokem P(1), Miranda Bastos AC(2), Tulkens PM(3), Wallemacq P(4), Van Bambeke F(5), Capron A(4). Author information: (1)Pharmacologie cellulaire et moléculaire, Louvain Drug Research Institute, Université catholique de Louvain, Brussels, Belgium. (2)Pharmacologie cellulaire et moléculaire, Louvain Drug Research Institute, Université catholique de Louvain, Brussels, Belgium; Clinical Pharmacy Research Group, Louvain Drug Research Institute, Université catholique de Louvain, Brussels, Belgium; Center for Clinical Pharmacy, Université catholique de Louvain, Brussels, Belgium. (3)Pharmacologie cellulaire et moléculaire, Louvain Drug Research Institute, Université catholique de Louvain, Brussels, Belgium; Center for Clinical Pharmacy, Université catholique de Louvain, Brussels, Belgium. (4)Clinical Chemistry Department, Cliniques Universitaires St. Luc, Université catholique de Louvain, Brussels, Belgium; Louvain Center for Toxicology and Applied Pharmacology, Université catholique de Louvain, Brussels, Belgium. (5)Pharmacologie cellulaire et moléculaire, Louvain Drug Research Institute, Université catholique de Louvain, Brussels, Belgium; Center for Clinical Pharmacy, Université catholique de Louvain, Brussels, Belgium. Electronic address: francoise.vanbambeke@uclouvain.be. OBJECTIVES: The aim of this study was to develop and validate a HPLC-MS/MS assay to determine total and unbound concentrations of temocillin in serum samples. DESIGN AND METHODS: Methanolic protein precipitation and ultrafiltration were used for total and unbound concentration extraction, respectively. Extract was injected into a LC-MS/MS system. Reversed phase chromatography was performed on a phenyl grafted column in gradient mode. Temocillin and internal standard (ticarcillin) were identified in positive electrospray ionization mode using ion transitions of m/z 415.34>339.1 and 385.31>160.3, respectively. RESULTS: Temocillin total and unbound concentration quantification assays were linear over concentrations ranging from 1 to 500mg/L and from 0.5 to 300mg/L, respectively. Both assays presented acceptable intra and inter-assay precision and accuracy <13.9%. Limits of quantification and detection were of 1 and 0.10mg/L, and 0.5 and 0.05mg/L for total and unbound concentration respectively. Total temocillin concentration recovery ranged from 85.80 to 99.40%. Temocillin ion suppression effect was <36.2 % in both assays. CONCLUSION: The method described is fast, sensitive and selective, with no interferences. This method may be used for both pharmacokinetic studies and therapeutic drug monitoring purposes. Copyright © 2015 The Canadian Society of Clinical Chemists. Published by Elsevier Inc. All rights reserved. PMID: 25712752 [PubMed - in process]