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http://crossmark.crossref.org/dialog/?doi=10.1007/s00216-016-9739-x&domain=pdf
Web End = Anal Bioanal Chem (2016) 408:62596268 DOI 10.1007/s00216-016-9739-x
http://crossmark.crossref.org/dialog/?doi=10.1007/s00216-016-9739-x&domain=pdf
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IR-MALDI ion mobility spectrometry
Jos Villatoro1,2,3 & Martin Zhlke1 & Daniel Riebe1 & Jens Riedel2 & Toralf Beitz1 &
Hans-Gerd Lhmannsrben1
http://orcid.org/0000-0001-7512-1497
Web End = Received: 23 February 2016 /Revised: 7 June 2016 /Accepted: 22 June 2016 /Published online: 2 July 2016 # Springer-Verlag Berlin Heidelberg 2016
Abstract The novel combination of infrared matrix-assisted laser dispersion and ionization (IR-MALDI) with ion mobility (IM) spectrometry makes it possible to investigate biomolecules in their natural environment, liquid water. As an alternative to an ESI source, the IR-MALDI source was implemented in an in-house-developed ion mobility (IM) spectrometer. The release of ions directly from an aqueous solution is based on a phase explosion, induced by the absorption of an IR laser pulse ( = 2.94 m, 6 ns pulse width), which disperses the liquid as nano- and micro-droplets. The prerequisites for the application of IR-MALDI-IM spectrometry as an analytical method are narrow analyte ion signal peaks for a high spectrometer resolution. This can only be achieved by improving the desolvation of ions. One way to full desolvation is to give the cluster ions sufficient time to desolvate. Two methods for achieving this are studied: the implementation of an additional drift tube, as in ESI-IM-spectrometry, and the delayed extraction of the ions. As a result of this optimization procedure, limits of detection between 5 nM and 2.5 M as well as linear dynamic ranges of 23 orders of magnitude were obtained for a number of substances. The ability of this method to analyze simple mixtures is illustrated by the separation of two different surfactant mixtures.
Keywords Ion mobility spectrometry . IR-MALDI . Laser
Introduction
Electrospray ionization (ESI) and matrix assisted laser desorption and ionization (MALDI) are two ionization techniques that first allowed for the soft ionization of larger biologically relevant molecules and their analysis in mass spectrometry (MS). In the 1990s, ESI was also introduced in the field of IM spectrometry [1]. This method enables the detection of a wide array of substance classes, such as amino acids, amphetamines, pesticides, benzodiazepines, opiates, peptides, and proteins [2, 3]. The first MALDI studies related to IM spec-trometry were reported by the Bowers group...