title: Liquid-phase microextration combined with liquid chromatography-electrospray tandem mass spectrometry for detecting diuretics in urine.
abstract: Trace amounts of diuretics were determined in human urine by hollow fiber liquid-phase microextraction (LPME) combined with liquid chromatography-electrospray ionization-tandem mass spectrometry (LC-ESI-MS/MS) in this study. Chromatography was performed on a C(8) reversed-phase column. A 25 microL n-octanol was used to extract analytes in urine. Extraction was optimized using a pH 2 solution spiked with 0.15 g/mL NaCl for 40 min at 40 degrees C with 1010 rpm stirring. The limits of detection of diuretics in urine were 0.3-6.8 ng/mL, and linearity range was 1-1000 ng/mL. Recoveries of spiked 50 ng/mL diuretics were 97.7-102.5%. The intra-day precision and inter-day precision were 3-18% and 4-21%, respectively. The diuretics concentration profiles in patient urine were also determined. The results of this study reveal the adequacy of LPME-LC-MS/MS method for analyzing diuretics in urine and quantification limits exceed World Anti-Doping Agency requirements.
authors.affiliation: Department of Chemistry, National Chung Hsing University, Taichung 40227, Taiwan.
authors.forename: Tzu-Feng
authors.initials: TF
authors.lastname: Tsai
authors.forename: Maw-Rong
authors.initials: MR
authors.lastname: Lee
mesh_terms: D002138:Calibration; D002853:Chromatography, Liquid; D004232:Diuretics / Q000652:urine*; D006801:Humans; D008832:Microchemistry / Q000295:instrumentation* / Q000379:methods*; D015394:Molecular Structure; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D021241:Spectrometry, Mass, Electrospray Ionization
chemical_list: D004232:Diuretics