title: Ambient ion/molecule reactions in low-temperature plasmas (LTP): reactive LTP mass spectrometry.
abstract: BACKGROUND
  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.
authors.affiliation: Institute of Inorganic and Analytical Chemistry, Justus Liebig University, 35392, Giessen, Germany.
authors.forename: Mario
authors.initials: M
authors.lastname: Benassi
authors.forename: Juan F
authors.initials: JF
authors.lastname: Garcia-Reyes
authors.forename: Bernhard
authors.initials: B
authors.lastname: Spengler