LIMS

Laser-Ion-Mobility-Spectrometer

FEATURES

  • Mobile on-site analysis in real time
  • Application of a pulsed UV laser
    (266 nm) as ionization source
  • Selective detection of monoaromatics (e.g. BTEX, organic diisocyanates) as well as of polycyclic aromatic hydrocarbons (PAH) by direct laser ionization
  • Detection of non-aromatic polar compounds (industrial chemicals, warfare agents, explosives) by indirect laser ionization
  • Sensitive determination in the low ppb range, large dynamic range
  • Sampling with a gas sampling device (VOC) or a thermal desorber
    (less volatile compounds)

In contrary to expensive and time-consuming laboratory devices, e.g. gas chromatograph/ mass spectrometers (GC/MS), ion mobility spectrometers (IMS) allow mobile on-site analysis of chemical substances in real time within a few seconds. In principle, characteristic drift velocities of ionized molecules (cations or anions) in the electric field at atmospheric pressure are determined. Conventional IMS mainly use radioactive substances for ionization and provide only a low detection selectivity and a limited dynamic range. They are mainly applied in the safety/security field.

The LIMS (laser ion mobility spectrometer), developed by OPTIMARE, uses a pulsed UV laser with an emission wavelength of 266 nm as ionization source. This positively increases the application range of the technique and, at the same time, avoids the problems (certification, disposal) associated with the radioactive source. With the laser irradiation of 266 nm, at low pulse energies (< 200 µJ), only aromatic molecules are ionized by resonant two photon ionization. This way, monoaromatics like BTEX and organic diisocyanates as well as PAH are selectively detected in a large dynamic range down to a low ppb range.

A novel ionization technique, developed by OPTIMARE in collaboration with the University of Potsdam, allows in addition the analysis of numerous non-aromatic polar molecules including important industrial chemicals, explosives, and warfare agents. With this method, specific aromatic dopants react with the analyte molecules under formation of characteristic product ions. Compared to conventional IMS the detection occurs in a larger dynamic range. In addtion, more characteristic signals are obtained for many substances.

LIMS enables the analysis of both, VOC from ambient air with gas sampling devices and less volatile compounds taken with wipe pads, with a thermal desorber. The device operates with an internal gas circulation, i.e. no external gas supply is required.