Investigation of neuroleptics and other aromatic compounds by laser-based ion mobility mass spectrometry

Abstract

Laser-based ion mobility (IM) spectrometry was used for the detection of neuroleptics and PAH. A gas chromatograph was connected to the IM spectrometer in order to investigate compounds with low vapour pressure. The substances were ionized by resonant two-photon ionization at the wavelengths λ = 213 and 266 nm and pulse energies between 50 and 300 μJ. Ion mobilities, linear ranges, limits of detection and response factors are reported. Limits of detection for the substances are in the range of 1-50 fmol. Additionally, the mechanism of laser ionization at atmospheric pressure was investigated. First, the primary product ions were determined by a laser-based time-of-flight mass spectrometer with effusive sample introduction. Then, a combination of a laser-based IM spectrometer and an ion trap mass spectrometer was developed and characterized to elucidate secondary ion-molecule reactions that can occur at atmospheric pressure. Some substances, namely naphthalene, anthracene, promazine and thioridazine, could be detected as primary ions (radical cations), while other substances, in particular acridine, phenothiazine and chlorprothixene, are detected as secondary ions (protonated molecules). The results are interpreted on the basis of quantum chemical calculations, and an ionization mechanism is proposed.

Selective ionization of marker molecules in fuels by laser-based ion mobility spectrometry (LIMS)

“…These specic ionization regions for the MS (LTQ XL, Thermo Fisher Scientic, Waltham, MA, USA) and for the IMS (self-made37, University of Potsdam) have been described previously. 37,38 In the IMS the ions were detected on a Faraday plate coupled to an amplier (NT3-ES, Physimetron, Berlin, Germany) and an oscilloscope (Handyscope, HS3, TiePie engineering, Sneek, Netherlands). Nitrogen (5.0, Praxair, Danbury, USA) was used as carrier and dri gas.…”