Analytical and Bioanalytical Chemistry

, Volume 411, Issue 8, pp 1569–1578 | Cite as

Application of direct analysis in real time to the study of chemical vapor generation mechanisms: identification of intermediate hydrolysis products of amine-boranes

  • Lucia D’Ulivo
  • Enea Pagliano
  • Massimo Onor
  • Zoltan Mester
  • Alessandro D’UlivoEmail author
Research Paper


In order to elucidate controversial results emerging in chemical vapor generation (CVG) for trace element determination, we conducted a series of experiments devoted to the identification of intermediates formed by acid hydrolysis of amine-boranes. For the first time, direct analysis in real time coupled with high-resolution mass spectrometry (DART-Orbitrap) was applied for detection of this class of compounds. Mass spectra of both solid amine-boranes and their aqueous solutions (pH ~ 8, no hydrolysis) were acquired for understanding their ionization pathway. Mass spectra of aqueous solutions of t-BuNH2·BH3 and Me2NH·BH3 were acquired under conditions that are employed in CVG (0.017–4.0 mol L−1 HCl, 0.167–0.2 mol L−1 borane reagent). The results disclose a reactivity driven by pH of amine-boranes undergoing hydrolysis. At low acidity, the hydrolysis proceeds according to the currently accepted displacement mechanisms (i.e., R3N·BH3 + H3O+ → R3NH+ + H2OBH3). At higher acidity, N-tert-butyl, cyclotriborazane, and bis(dimethylamino)boronium were identified, for the first time, during the hydrolysis of t-BuNH2·BH3 and Me2NH·BH3, respectively. Formation of these intermediates was ascribed to a hydrolysis pathway starting with the ionization of the amine-borane, (i.e., R3N·BH3 + H3O+ → [(H2O)R3NBH2] + + H2). The new evidence explains the anomalous behavior observed in CVG by amine-borane derivatization, and updates the currently accepted mechanisms for the acid hydrolysis of amine-boranes.

Graphical Abstract


Amine-boranes Hydrolysis Direct analysis in real time Mass spectrometry Chemical vapor generation Mechanism 


Compliance with ethical standards

Conflict of interest

The authors declare that they have no competing interests

Supplementary material

216_2019_1598_MOESM1_ESM.pdf (157 kb)
ESM 1 (PDF 157 kb)


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Copyright information

© Springer-Verlag GmbH Germany, part of Springer Nature 2019

Authors and Affiliations

  1. 1.National Research Council CanadaOttawaCanada
  2. 2.C.N.R, Institute of Chemistry of Organometallic CompoundsPisaItaly

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