title: Mass spectrometric separation and quantitation of overlapping isotopologues. H2O/HOD/D2O and H2Se/HDSe/D2Se mixtures.
abstract: Three conceptually different mathematical methods are presented for accurate mass spectrometric determination of H2O/HOD/D2O and H2Se/HDSe/D2Se concentrations from mixtures. These are alternating least-squares, weighted two-band target entropy minimization, and a statistical mass balance model. The otherwise nonmeasurable mass spectra of partially deuterated isotopologues (HOD and HDSe) are mathematically constructed. Any recorded isotopologue mixture mass spectra are then deconvoluted by least-squares into their components. This approach is used to study the H2O/D2O exchange reaction, and is externally validated gravimetrically. The H2O/D2O exchange equilibrium constant is also measured from the deconvoluted 70 eV electron impact GC/MS data (K = 3.85 +/- 0.03).
authors.affiliation: Institute for National Measurement Standards, National Research Council Canada, Ottawa, Ontario, Canada.
authors.forename: Juris
authors.initials: J
authors.lastname: Meija
authors.forename: Zoltan
authors.initials: Z
authors.lastname: Mester
authors.forename: Alessandro
authors.initials: A
authors.lastname: D'Ulivo
mesh_terms: D000465:Algorithms; D045424:Complex Mixtures / Q000032:analysis*; D003627:Data Interpretation, Statistical; D041961:Deuterium Exchange Measurement / Q000379:methods*; D017666:Deuterium Oxide / Q000032:analysis*; D007553:Isotope Labeling / Q000379:methods; D013058:Mass Spectrometry / Q000379:methods*; D018036:Selenium Compounds / Q000032:analysis*; D014867:Water / Q000032:analysis*
chemical_list: D045424:Complex Mixtures; D018036:Selenium Compounds; D014867:Water; D017666:Deuterium Oxide; C026372:hydrogen selenide