Meija Juris, Mester Zoltan, D'Ulivo Alessandro
Institute for National Measurement Standards, National Research Council Canada, Ottawa, Ontario, Canada.
J Am Soc Mass Spectrom. 2006 Jul;17(7):1028-36. doi: 10.1016/j.jasms.2006.02.008. Epub 2006 May 19.
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).
本文介绍了三种概念上不同的数学方法，用于从混合物中准确质谱测定H₂O/HOD/D₂O和H₂Se/HDSe/D₂Se的浓度。这些方法分别是交替最小二乘法、加权双波段目标熵最小化法和统计质量平衡模型。通过数学方法构建了部分氘代同位素分子（HOD和HDSe）原本无法测量的质谱。然后，通过最小二乘法将记录的任何同位素分子混合物质谱解卷积为其组分。该方法用于研究H₂O/D₂O交换反应，并通过重量法进行外部验证。还从解卷积后的70 eV电子轰击气相色谱/质谱数据中测量了H₂O/D₂O交换平衡常数（K = 3.85 ± 0.03）。
