title: Liquid-phase microextraction and desorption electrospray ionization mass spectrometry for identification and quantification of basic drugs in human urine.
abstract: Hollow fibre liquid-phase microextraction (LPME) and desorption electrospray ionization mass spectrometry (DESI-MS) were evaluated for the identification and quantification of basic drugs in human urine samples. The selective extraction capabilities of three-phase LPME provided a significant reduction in the matrix effects otherwise observed in direct DESI-MS analysis of urine samples. Aqueous LPME extracts (in 10 mM HCl) were deposited on porous Teflon, dried at room temperature, and the dried spots were then analyzed directly with DESI-MS in full scan mode. Pethidine, diphenhydramine, nortriptyline, and methadone were used as model compounds for identification, and their limits of identification were determined to be 100, 25, 100, and 30 ng/mL, respectively. In a reliability test with 19 spiked urine samples, 100% of the positive samples containing the model drugs in concentrations at or above the limit of identification were identified. Diphenhydramine was used as a model compound for quantitative analysis with diphenhydramine-d(5) as an internal standard. The calibration curve was linear in the range 50-2000 ng/mL (R(2) = 0.992) with a limit of quantification at approximately 140 ng/mL. The intra- and inter-day relative standard deviations were <9.5%. In a reliability test with six spiked urine samples, deviations between the measured and the true values for diphenhydramine were in the range 0.2-22.9%.
authors.affiliation: Department of Pharmaceutics and Analytical Chemistry, University of Copenhagen, Universitetsparken 2, Copenhagen 2100, Denmark.
authors.forename: Janina
authors.initials: J
authors.lastname: Thunig
authors.forename: Linda
authors.initials: L
authors.lastname: Flø
authors.forename: Stig
authors.initials: S
authors.lastname: Pedersen-Bjergaard
authors.forename: Steen Honoré
authors.initials: SH
authors.lastname: Hansen
authors.forename: Christian
authors.initials: C
authors.lastname: Janfelt
mesh_terms: D004155:Diphenhydramine / Q000652:urine; D006801:Humans; D057230:Limit of Detection; D016014:Linear Models; D059627:Liquid Phase Microextraction / Q000379:methods*; D008614:Meperidine / Q000652:urine; D008691:Methadone / Q000652:urine; D009661:Nortriptyline / Q000652:urine; D004364:Pharmaceutical Preparations / Q000737:chemistry / Q000145:classification / Q000652:urine*; D015203:Reproducibility of Results; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods*
chemical_list: D004364:Pharmaceutical Preparations; D004155:Diphenhydramine; D008614:Meperidine; D009661:Nortriptyline; D008691:Methadone