title: Determination of derivatized urea in exhaled breath condensate by LC-MS.
abstract: Elevation in one or more compounds in exhaled breath condensate (EBC) has been reported to be related to one or another lung disease. The increased concentration might be caused by increased chemicals in the airway surface liquid. However, it might also be due to an increased delivery of liquid samples into the airstream. Being evenly distributed throughout the body, urea is a likely candidate for a marker of such dilution. A liquid chromatography-tandem mass spectrometry method was developed for determination of EBC urea. Urea in EBC samples was converted to 2-hydroxypyrimidine (2-HPM) through a one step reaction, along with (15)N(2)-urea added as an internal standard. The product ion m/z 97/42 was selected for quantification with m/z 99/43 from (15)N(2)-2-HPM as a standard. Concentrations of urea in EBC from five lung cancer patients were found to be 35.1, 2.2, 103.5, 19.3, and 3.6 microM, respectively. The highest values were in patients dying of respiratory distress, whose lungs were filled with fluid. Lower values were seen in patients whose conditions were improving. Lately, one of the low EBC urea values was observed in a patient whose airway status did not contribute to his poor clinical condition.
authors.affiliation: Department of Pharmacology and Toxicology, The University of Mississippi Medical Center, 2500 North State Street, Jackson, MS 39216, USA. zquan@aecom.yu.edu
authors.forename: Zhe
authors.initials: Z
authors.lastname: Quan
authors.forename: Christine
authors.initials: C
authors.lastname: Purser
authors.forename: Rodney C
authors.initials: RC
authors.lastname: Baker
authors.forename: Terry
authors.initials: T
authors.lastname: Dwyer
authors.forename: Rajesh
authors.initials: R
authors.lastname: Bhagat
authors.forename: Yinghong
authors.initials: Y
authors.lastname: Sheng
authors.forename: Jerzy R
authors.initials: JR
authors.lastname: Leszczynski
mesh_terms: D001944:Breath Tests; D002138:Calibration; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D045853:Exhalation; D006801:Humans; D008175:Lung Neoplasms / Q000175:diagnosis*; D053719:Tandem Mass Spectrometry / Q000379:methods*; D014508:Urea / Q000032:analysis*
chemical_list: D014508:Urea