title: A liquid chromatography-mass spectrometry method to measure stable isotopic tracer enrichments of glycerol and glucose in human serum.
abstract: Stable isotopes are commonly used as tracers for the measurement of glycerol and glucose kinetics in metabolic studies. Traditionally, the analysis of these isotopes has been performed using gas chromatography-mass spectrometry, which requires that the analytes first be derivatized. The derivatization process adds considerable complexity to the method. Liquid chromatography-mass spectrometry (LCMS) can measure many metabolites directly with limited sample preparation. We present a novel analytical method for the measurement of [1,1,2,3,3-(2)H(5)]glycerol (d(5)-glycerol) and [6,6-(2)H(2)]glucose (d(2)-glucose) isotopic tracer enrichments in human serum in a single run by LCMS. After a simple extraction step, the sample is separated isocratically by HPLC, and the isotopes are measured using positive electrospray ionization with selected ion monitoring of the sodium-adduct ions. The method is linear over a wide range of d(2)-glucose and d(5)-glycerol enrichments. The within-day standard deviation of measurement of serum samples was 0.05 mole% excess (MPE) for d(2)-glucose and 0.25 MPE for d(5)-glycerol. The variation of tracer enrichment among days was about double that measured within 1 day.
authors.affiliation: U.S. Clinical Pharmacology Unit, GlaxoSmithKline, Philadelphia, Pennsylvania 19104, USA.
authors.forename: T S
authors.initials: TS
authors.lastname: McIntosh
authors.forename: H M
authors.initials: HM
authors.lastname: Davis
authors.forename: D E
authors.initials: DE
authors.lastname: Matthews
mesh_terms: D001786:Blood Glucose / Q000032:analysis*; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D005990:Glycerol / Q000097:blood*; D006801:Humans; D007553:Isotope Labeling / Q000379:methods*; D007554:Isotopes; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods*
chemical_list: D001786:Blood Glucose; D007554:Isotopes; D005990:Glycerol