Electron ionization and atmospheric pressure photochemical ionization in gas chromatography-mass spectrometry analysis of amino acids

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Eur. J. Mass Spectrom. 9, 497 - 507 (2003)
DOI: 10.1255/ejms.581

Electron ionization and atmospheric pressure photochemical ionization in gas chromatography-mass spectrometry analysis of amino acids

Igor A. Revelsky, Yuri S. Yashin, Tim G. Sobolevsky and Alexander I. Revelsky
Lomonosov Moscow State University, Chemistry Department, Leninskie Gory 1, bldg 3, 119992 GSP-2 Moscow, Russia. E-mail:
Barbara Miller and Vincent Oriedo
The Dow Chemical Corp., Dow Bldg. 1707, Industrial BioMaterials Platform, Midland, MI 48674, USA. E-mail:

ABSTRACT:

The mass spectra of tert-butyldimethylsilyl (TBDMS) derivatives of 17 amino acids were obtained using electron ionization (EI) and atmospheric pressure photochemical ionization (APPhCI) mass spectrometry. The APPhCI mass spectra for all of the derivatives except arginine were shown to consist of only molecular [M]^+· and quasimolecular [MH]⁺ ions whereas, in the case of EI, the compounds in question underwent a drastic fragmentation. The application of APPhCI to gas chromatography-mass spectrometry enables a reliable identification of the TBDMS derivatives of amino acids in a mixture, even if its components are only partially resolved, due to the unique molecular masses for each compound. Comparison of the respective positive-ion chemical ionization (PICI) mass spectra available in the literature with APPhCI spectra has shown that, in the case of PICI, unlike APPhCI, noticeable fragmentation occurs.

Keywords: electron ionization, atmospheric pressure photochemical ionization, amino acids, silylation, TBDMS derivatives, MTBSTFA

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