title: Determination of (2)H-enrichment of rat brain interstitial fluid and rat plasma by headspace-gas-chromatography - quadrupole-mass-spectrometry.
abstract: (2)H2O as nonradioactive, stable marker substance is commonly used in preclinical and clinical studies and the precise determination of (2)H2O concentration in biological samples is crucial. However, aside from isotope ratio mass spectrometry (IRMS), only a very limited number of methods to accurately measure the (2)H2O concentration in biological samples are routinely established until now. In this study, we present a straightforward method to accurately measure (2)H-enrichment of rat brain interstitial fluid (ISF) and rat plasma to determine the relative recovery of a cerebral open flow microperfusion (cOFM) probe, using headspace-gas-chromatography - quadrupole-mass-spectrometry. This method is based on basic-catalyzed hydrogen/deuterium exchange in acetone and detects the (2)H-labelled acetone directly by the headspace GC-MS. Small sample volumes and limited number of preparation steps make this method highly competitive. It has been fully validated. (2)H enriched to 8800 ppm in plasma showed an accuracy of 98.9% and %Relative Standard Deviation (RSD) of 3.1 with n = 18 over three days and with two operators. Similar performance was obtained for cerebral ISF enriched to 1100 ppm (accuracy: 96.5%, %RSD: 3.1). With this highly reproducible method we demonstrated the successful employment of (2)H2O as performance marker for a cOFM probe.
authors.affiliation: Health - Institute for Biomedicine and Health Sciences, Joanneum Research Forschungsgesellschaft m.b.H, Neue Stiftingtalstrasse 2, 8010, Graz, Austria.
authors.forename: Anita
authors.initials: A
authors.lastname: Eberl
authors.affiliation: Health - Institute for Biomedicine and Health Sciences, Joanneum Research Forschungsgesellschaft m.b.H, Neue Stiftingtalstrasse 2, 8010, Graz, Austria.
authors.forename: Thomas
authors.initials: T
authors.lastname: Altendorfer-Kroath
authors.affiliation: Division of Endocrinology and Diabetology, Department of Internal Medicine, Medical University of Graz, Auenbruggerplatz 15, 8036, Graz, Austria.
authors.forename: Denise
authors.initials: D
authors.lastname: Kollmann
authors.affiliation: Health - Institute for Biomedicine and Health Sciences, Joanneum Research Forschungsgesellschaft m.b.H, Neue Stiftingtalstrasse 2, 8010, Graz, Austria.
authors.forename: Thomas
authors.initials: T
authors.lastname: Birngruber
authors.affiliation: Health - Institute for Biomedicine and Health Sciences, Joanneum Research Forschungsgesellschaft m.b.H, Neue Stiftingtalstrasse 2, 8010, Graz, Austria; Division of Endocrinology and Diabetology, Department of Internal Medicine, Medical University of Graz, Auenbruggerplatz 15, 8036, Graz, Austria.
authors.forename: Frank
authors.initials: F
authors.lastname: Sinner
authors.affiliation: Health - Institute for Biomedicine and Health Sciences, Joanneum Research Forschungsgesellschaft m.b.H, Neue Stiftingtalstrasse 2, 8010, Graz, Austria. Electronic address: reingard.raml@joanneum.at.
authors.forename: Reingard
authors.initials: R
authors.lastname: Raml
authors.affiliation: Health - Institute for Biomedicine and Health Sciences, Joanneum Research Forschungsgesellschaft m.b.H, Neue Stiftingtalstrasse 2, 8010, Graz, Austria.
authors.forename: Christoph
authors.initials: C
authors.lastname: Magnes
mesh_terms: D000818:Animals; D001921:Brain / Q000378:metabolism*; D041961:Deuterium Exchange Measurement / Q000379:methods*; D017666:Deuterium Oxide / Q000032:analysis / Q000493:pharmacokinetics / Q000494:pharmacology; D045604:Extracellular Fluid / Q000737:chemistry / Q000378:metabolism; D008401:Gas Chromatography-Mass Spectrometry / Q000379:methods*; D051381:Rats
chemical_list: D017666:Deuterium Oxide
keywords: (2)H(2)O; Cerebral open flow microperfusion; Headspace GC-MS; Interstitial fluid; Plasma; Validation