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Ambient ion/molecule reactions in low-temperature plasmas (LTP): reactive LTP mass spectrometry

Authors


Correspondence to: B. Spengler, Institute of Inorganic and Analytical Chemistry, Justus Liebig University, Schubertstrasse 60, Haus 16, 35392 Giessen, Germany.

E-mail: bernhard.spengler@anorg.chemie.uni-giessen.de

Abstract

RATIONALE

Ion/molecule reactions are commonly used to characterize structures due to their high specificity. Herein, we present ambient ion/molecule reactions performed in the course of low-temperature plasma (LTP) ionization of condensed-phase analytes in order to increase the specificity of LTP-based ambient analysis.

METHODS

The ion population of the cold plasma is modified by addition of a reagent to the plasma before it is directed at a surface bearing the analyte. Desorbed ions were analyzed using linear ion trap-Fourier transform ion cyclotron resonance mass spectrometry (FTICRMS).

RESULTS

Acylium ions generated from tetramethylurea react with 1,3-dioxane analyte to afford distinctive Eberlin product ions. Reactions of alkylamines, such as n-hexylamine and n-octylamine, with benzaldehyde produce the corresponding imines. Reaction of ruthenocene with trifluoroacetic anhydride forms the unusual trifluoroacetate ruthenocene.

CONCLUSIONS

A LTP source can be used to generate reagent ions that can undergo ion/molecule reactions in the ambient environment with an analyte at condensed phase on a surface. The experiment is a 'reactive' version of the standard low-temperature plasma (LTP) ambient ionization experiment. This approach provides additional information by combining ion/molecule chemistry with conventional MS and MS/MS data to characterize particular analytes. Copyright © 2013 John Wiley & Sons, Ltd.

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