High desolvation temperature facilitates the ESI-source H/D exchange at non-labile sites of hydroxybenzoic acids and aromatic amino acids

Alexander Zherebker, Yury Kostyukevich, Alexey Kononikhin, Vitaliy A. Roznyatovsky, Igor Popov, Yuri K. Grishin, Irina V. Perminova, Eugene Nikolaev

    Research output: Contribution to journalArticlepeer-review

    34 Citations (Scopus)

    Abstract

    Hydrogen/deuterium exchange coupled with high-resolution mass spectrometry has become a powerful analytical approach for structural investigations of complex organic matrices. Here we report the feasibility of the site-specific H/D exchange of non-labile hydrogens directly in the electrospray ionization (ESI) source, which was facilitated by an increase in the desolvation temperature from 200 °C up to 400 °C. We have found that the exchanges at non-labile sites were observed only for the model compounds capable of keto-enol tautomeric transformations (e.g., 2,3-, 2,4-dihydroxybenzoic acids, gallic acid, DOPA), and only when water was used as a solvent. We hypothesized that the detected additional exchanges were induced by the presence of hydroxyls in the sprayed water droplets generated in the negative ESI mode. It was indicative of the exchange reactions taking place in the sprayed droplets rather than in the gas phase. To support this hypothesis, the H/D exchange experiments were run in deuterated water under base-catalyzed conditions for three model compounds, which showed the most intensive exchanges in the MS experiments: DOPA, 2,4-DHB, and 5-acetylsalicylic acid. 2H NMR spectroscopy has confirmed keto-enolic transformations of the model compounds leading to the specific labeling of the corresponding non-labile sites. We believe that the proposed technique will be useful for structural investigations of natural complex mixtures (e.g. proteins, humic substances) using site-specific H/D exchange.

    Original languageEnglish
    Pages (from-to)2426-2434
    Number of pages9
    JournalAnalyst
    Volume141
    Issue number8
    DOIs
    Publication statusPublished - 21 Apr 2016

    Fingerprint

    Dive into the research topics of 'High desolvation temperature facilitates the ESI-source H/D exchange at non-labile sites of hydroxybenzoic acids and aromatic amino acids'. Together they form a unique fingerprint.

    Cite this