Article

Journal of the American Society for Mass Spectrometry

, Volume 19, Issue 9, pp 1361-1366

Characterization of proton-bound acetate dimers in ion mobility spectrometry

  • Christian Schack PedersenAffiliated withDepartment of Chemistry, University of Copenhagen Email author 
  • , Frants Roager LauritsenAffiliated withDepartment of Chemistry, University of Copenhagen
  • , Alexey SysoevAffiliated withMoscow Engineering Physics Institute (State University)
  • , Anna-Kaisa ViitanenAffiliated withAerosol Physics Laboratory, Tampere University of Technology
  • , Jyrki M. MäkeläAffiliated withAerosol Physics Laboratory, Tampere University of Technology
  • , Alexey AdamovAffiliated withLaboratory of Analytical Chemistry, Department of Chemistry, University of HelsinkiDivision of Pharmaceutical Chemistry, Faculty of Pharmacy, University of Helsinki
  • , Jaakko LaakiaAffiliated withLaboratory of Analytical Chemistry, Department of Chemistry, University of Helsinki
  • , Timo MaurialaAffiliated withLaboratory of Analytical Chemistry, Department of Chemistry, University of Helsinki
  • , Tapio KotiahoAffiliated withLaboratory of Analytical Chemistry, Department of Chemistry, University of HelsinkiDivision of Pharmaceutical Chemistry, Faculty of Pharmacy, University of Helsinki

Abstract

Ionized acetates were used as model compounds to describe gas-phase behavior of oxygen containing compounds with respect to their formation of dimers in ion mobility spectrometry (IMS). The ions were created using corona discharge at atmospheric pressure and separated in a drift tube before analysis of the ions by mass spectrometry. At the ambient operational temperature and pressure used in our instrument, all acetates studied formed dimers. Using a homolog series of n-alkyl-acetates, we found that the collision cross section of a dimer was smaller than that of a monomer with the same reduced mass. Our experiments also showed that the reduced mobility of acetate dimers with different functional groups increased in the order n-alkyl ≤ branched chain alkyl ≤ cyclo alkyl < aromat. For mixed n-alkyl dimers we found that the reduced mobility of acetate dimers having the same number of carbons, for example a dimer of acetyl acetate and hexyl acetate has the same reduced mobility as a dimer composed of two butyl acetates. The fundamental behavior of acetate monomers and dimers described in this paper will assist in a better understanding of the influence of dimer formation in ion mobility spectrometry.