Quantitatively resolving mixtures of isobaric compounds using chemical ionization mass spectrometry by modulating the reactant ion composition

• Published in: Rapid communications in mass spectrometry 2008-08, Vol.22 (16), p.2597-2601
• Main Authors: Fortner, E. C., Knighton, W. B.
• Format: Article
• Language: English
• ISSN: 0951-4198; 1097-0231
• DOI: 10.1002/rcm.3645

Acrolein (C3H4O) and 1‐butene (C4H8) can both be individually detected by proton transfer chemical ionization mass spectrometry (CI‐MS). However, because these compounds are isobaric, mixtures of these two compounds cannot be resolved since both compounds react with H3O+ via a proton‐transfer reaction to form a protonated molecule that is detected at a nominal mass‐to‐charge ratio of 57 (m/z 57). While both compounds react with H3O+ only acrolein reacts to any significant extent with H3O+(H2O). Recognizing that the electrical potential applied to a drift tube reaction mass spectrometer provides a simple and effective means for varying the relative intensity of the H3O+ and H3O+(H2O) reactant ions we have developed a method whereby we make use of this reactivity difference to resolve mixtures of these two compounds. We demonstrate a technique where the individual contributions of acrolein and 1‐butene within a mixture can be quantitatively resolved by systematically changing the reagent ion from H3O+ to H3O+(H2O) through control of the electric potential applied to the drift tube reaction region of a proton transfer reaction mass spectrometer. Copyright © 2008 John Wiley & Sons, Ltd.