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). © 2006 American Society for Mass Spectrometry.
Meija, J., Mester, Z., & D’Ulivo, A. (2006). Mass Spectrometric Separation and Quantitation of Overlapping Isotopologues. H2O/HOD/D2O and H2Se/HDSe/D2Se Mixtures. Journal of the American Society for Mass Spectrometry, 17(7), 1028–1036. https://doi.org/10.1016/j.jasms.2006.02.008