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Gas-phase basicity of several common MALDI matrices measured by a simple experimental approachстатья
Информация о цитировании статьи получена из
Web of Science,
Scopus
Статья опубликована в журнале из списка Web of Science и/или Scopus
Дата последнего поиска статьи во внешних источниках: 6 декабря 2018 г.
- Авторы: Barylyuk K., Fritsche L., Balabin R.M., Nieckarz R., Zenobi R.
- Журнал: RSC advances
- Том: 2
- Номер: 5
- Год издания: 2012
- Издательство: Royal Society of Chemistry
- Местоположение издательства: United Kingdom
- Первая страница: 1962
- Последняя страница: 1969
- DOI: 10.1039/c1ra01117k
- Аннотация: We present a combined experimental and theoretical study to determine the gas-phase basicity of several relatively small organic molecules that are used as matrices in MALDI: alpha-cyano-4-hydroxycynnamic acid (αCHCA), ferulic acid (FA), 3-hydroxypicolinic acid (HPA), sinapinic acid (SA), and 2,4,6-trihydroxyacetophenone (THAP). Our simple and fast experimental approach utilizes the ability of an electrosonic spray ionization (ESSI) source to produce high densities of gas-phase ions at ambient conditions, so that their gas-phase thermochemical properties can be probed in a bracketing-like experiment at atmospheric pressure, with no need for high vacuum. The reaction between the analyte and reference bases is monitored by a commercial mass spectrometer. We determined the following GB values of the MALDI matrices studied: 908.1 ± 0.8 (αCHCA), 863.8 ± 8.0 (FA), 876.3 ± 10.2 (HPA), 867.4 ± 1.4 (SA), and 864.2 ± 7.6 (THAP) kJ mol -1. A good agreement between the experimentally measured and computationally predicted (DFT-B3LYP, G4MP2) gas-phase basicities for the studied compounds is found, except for αCHCA for which the calculations resulted in approximately 80 kJ mol -1 lower GB. We attribute the observed discrepancy between the measured and calculated values to a gas-phase rearrangement of αCHCA into a heterocyclic aromatic isomer, 7-hydroxyquinoline-3-carboxylic acid (HQA). HQA is thermodynamically more stable and features higher GB than that of αCHCA (calculated at approximately 920 kJ mol -1). The gas-phase basicity values of THAP and HPA are reported for the first time.
- Добавил в систему: Балабин Роман Михайлович