Karlsruhe Nano Micro Facility (KNMF)

Travelling Wave Ion-Mobility Time-of-Flight Mass Spectrometry (ESI-/MALDI-TOF)

KNMF Laboratory for Microscopy and Spectroscopy

Availability limited to KIT internal users (starting 25th call)

Matrix assisted laser desorption ionization (MALDI) or electrospray ionization (ESI) allows the soft ionization and transfer of analytes to the gas phase. Time-of-flight (TOF) mass spectrometric analysis provides high-resolution, exact mass measurement and accurate isotope distributions of positive or negative ions for identification. This allows for chemical identification of intact molecular and cluster species, transferred from solution (ESI) or a solid matrix (MALDI).

Recent advances in technology have led to the efficient coupling of ion-mobility analysis with high resolution mass spectrometers. Ion mobility spectrometry (IMS) provides a means to separate ions based on their shape and size, providing complementary information to that obtained via standard mass spectrometry. The Synapt-G2 HDMS is the first commercial instrument of its kind, offering flexibility in terms of ion source (MALDI, nanoESI, ESI) and sample analysis, coupling a high resolution TOF mass analyzer with a travelling wave ion mobility (TWIMS) separation cell. Thus, the instrument has both the capability to obtain high resolution ESI-/MALDI-TOF mass spectra, or, with application of IMS, to obtain 2D structure-mass correlation maps. Ions of interest may also be mass selected in a quadrupole mass filter and have their individual chemistry (e.g. via collision induced dissociation) probed.

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Details (ESI-/MALDI-TOF)


  • ESI/nanoESI/1kHz MALDI ion sources
  • High resolution mass spectra
  • 32kDa expanded mass range
  • Analysis of positive and negative ions, ion chemistry
  • TWIMS separation cell


  • Lower mass detection limit of: 100
  • Spatial resolution of MALDI: currently 100 µm
  • nanoESI/ESI: samples must be soluble
  • Air sensitive samples- the ion source is open to atmospheric conditions

Typical results

fig. 1

Fig. 1: Negative-ion electrospray mass spectrum obtained from a solution of Na-Au4Pd8 in H2O/DMSO. The two insets highlight peaks B and B’ and compare their isotope distribution to the simulated ones for the molecular ions as labelled.

(a) fig. 2a

(b) fig. 2b

(c) fig. 2c

Fig. 2:
(a) Schematic structures of the two possible stacking configurations for Tb2(A3B)2Pc complex: a symmetric one (on the left) and an asymmetric one (on the right).
(b) Calculated structure of (A3B)2PcTb2 (symmetric stacking)
(c) IMS arrival time distribution of the anion of Tb2(A3B)2Pc indicating the presence of two different isomers.