title: Analysis of organic acid markers relevant to inherited metabolic diseases by ultra-performance liquid chromatography/tandem mass spectrometry as benzofurazan derivatives.
abstract: We describe a new approach applicable to the determination of organic acids that serve as diagnostic markers for several inherited metabolic disorders. We utilized liquid chromatography/tandem mass spectrometry for analysis of organic acid derivatives of a recently described benzofurazan reagent. The derivatization step was necessary to obtain organic acid derivatives suitable for analysis by reversed-phase liquid chromatography with high ionization efficiency for mass spectrometry in the positive-ion mode. In this work, a group of related dicarboxylic acid markers containing five or six carbon atoms were analyzed and validation was performed for glutaric and 3-hydroxyglutaric acids, the specific markers for glutaric acidemia type 1. Derivatization was achieved by reacting untreated urine with the derivatization reagent under mild conditions. The reaction mixture was analyzed on a C18 ultra-performance liquid chromatography (UPLC) column (50x2.1 mm, 1.7 microm) and detected in the multiple reaction monitoring mode in 5 min. Calibration curves were linear up to at least 1000 microM with detection limits for glutaric and 3-hydroxyglutaric acids of 0.025 and 0.02 microM, respectively (signal-to-noise ratio of 3). Intra-day (n=11) and inter-day (n=6) coefficients of variation were better than 11.2%. The assay was successfully applied to control (n=134) and glutaric acidemia type 1 (n=55) urine samples.
authors.affiliation: National Laboratory for Newborn Screening, King Faisal Specialist Hospital and Research Centre, Riyadh 11211, Saudi Arabia, and Graduate School of Pharmaceutical Sciences, The University of Tokyo, Japan.
authors.forename: Osama Y
authors.initials: OY
authors.lastname: Al-Dirbashi
authors.forename: Tomofumi
authors.initials: T
authors.lastname: Santa
authors.forename: Khalid
authors.initials: K
authors.lastname: Al-Qahtani
authors.forename: Mohammed
authors.initials: M
authors.lastname: Al-Amoudi
authors.forename: Mohamed S
authors.initials: MS
authors.lastname: Rashed
mesh_terms: D000143:Acids / Q000737:chemistry* / Q000145:classification; D001572:Benzofurans / Q000737:chemistry*; D015415:Biomarkers / Q000032:analysis / Q000652:urine; D016022:Case-Control Studies; D002853:Chromatography, Liquid / Q000379:methods*; D006801:Humans; D008661:Metabolism, Inborn Errors / Q000652:urine*; D009930:Organic Chemicals / Q000737:chemistry* / Q000145:classification; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D053719:Tandem Mass Spectrometry / Q000379:methods*; D013696:Temperature; D013997:Time Factors
chemical_list: D000143:Acids; D001572:Benzofurans; D015415:Biomarkers; D009930:Organic Chemicals; C105430:benzofuran