title: Quantification of urinary zwitterionic organic acids using weak-anion exchange chromatography with tandem MS detection.
abstract: A rapid and accurate quantitative method was developed and validated for the analysis of four urinary organic acids with nitrogen containing functional groups, formiminoglutamic acid (FIGLU), pyroglutamic acid (PYRGLU), 5-hydroxyindoleacetic acid (5-HIAA), and 2-methylhippuric acid (2-METHIP) by liquid chromatography tandem mass spectrometry (LC/MS/MS). The chromatography was developed using a weak anion-exchange amino column that provided mixed-mode retention of the analytes. The elution gradient relied on changes in mobile phase pH over a concave gradient, without the use of counter-ions or concentrated salt buffers. A simple sample preparation was used, only requiring the dilution of urine prior to instrumental analysis. The method was validated based on linearity (r2>or=0.995), accuracy (85-115%), precision (C.V.<12%), sample preparation stability (<or=5%, 72 h), and established patient ranges. The method was found to be both efficient and accurate for the analysis of urinary zwitterionic organic acids.
authors.affiliation: Metametrix Clinical Laboratory, 4855 Peachtree Ind. Blvd. Norcross, GA 30092, USA. mbishop@metametrix.com
authors.forename: Michael Jason
authors.initials: MJ
authors.lastname: Bishop
authors.forename: Brian S
authors.initials: BS
authors.lastname: Crow
authors.forename: Kasey D
authors.initials: KD
authors.lastname: Kovalcik
authors.forename: Joe
authors.initials: J
authors.lastname: George
authors.forename: James A
authors.initials: JA
authors.lastname: Bralley
mesh_terms: D000143:Acids / Q000737:chemistry / Q000652:urine*; D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000837:Anion Exchange Resins; D002852:Chromatography, Ion Exchange / Q000379:methods*; D005565:Formiminoglutamic Acid / Q000737:chemistry / Q000652:urine; D006626:Hippurates / Q000737:chemistry / Q000652:urine; D006801:Humans; D008875:Middle Aged; D015394:Molecular Structure; D009930:Organic Chemicals / Q000737:chemistry / Q000652:urine; D011761:Pyrrolidonecarboxylic Acid / Q000737:chemistry / Q000652:urine; D015203:Reproducibility of Results; D053719:Tandem Mass Spectrometry / Q000379:methods*
chemical_list: D000143:Acids; D000837:Anion Exchange Resins; D006626:Hippurates; D009930:Organic Chemicals; C026113:2-methylhippuric acid; D005565:Formiminoglutamic Acid; D011761:Pyrrolidonecarboxylic Acid