Ion mobility based separation techniques for the direct analysis of gaseous and solid samples and fundamental studies of gas phase reactions

Riikka-Marjaana Räsänen

Forskningsoutput: AvhandlingDoktorsavhandlingSamling av artiklar

Sammanfattning

This thesis describes the applicability of different types of IMS instruments in the direct measurements of gaseous and solid samples and in fundamental studies of gas-phase ion chemistry. A handheld chemical detector containing an aspiration ion mobility spectrometry (AIMS) was applied in the monitoring of gas phase explosive triacetone triperoxide (TATP) from air flow. The instrument-normalized detection threshold (20 pA) was exceeded already with the lowest sample concentration of 0.3 mg m−3. The response time of the instrument was less than five seconds. AIMS was also used to monitor chemical changes in the headspaces of the chambers containing microbe contaminated and sterile particle board samples in humid conditions. It was possible to separate the distinct chemical profiles of the chambers with sterile and microbe-contaminated specimen by principal component analysis. Overall, AIMS was found to be an adequate technique in dynamic screening of TATP and in monitoring of the changes in the microbe metabolism. Ambient ionization techniques, direct analysis in real time (DART) and desorption atmospheric pressure photoionization (DAPPI), were combined with travelling wave ion mobility-mass spectrometry. In the surface analysis of almond, pharmaceuticals, vitamin tablets and dried blood spot sample, the ion mobility separation reduced the chemical noise in the mass spectra and increased the signal-to-noise ratio. In the comparative studies of DAPPI and DART ionization, the limits of detection were between 30−290 and 330−8200 fmol for DAPPI and DART, respectively, for the tested compounds bisphenol A, benzo[a]pyrene, ranitidine, cortisol, and α-tocopherol. Finally, the reactions of phenol and fluorinated phenols with Cl− in ambient pressure were investigated by drift tube ion mobility-mass spectrometry. For the least fluorinated phenols (phenol, 2-fluorophenol and 2,4-difluorophenol) with the lowest gas-phase acidities, the Cl− adducts [M+Cl]− and [2M+Cl]− were the major products in both low and high sample concentration. For the highly fluorinated phenols (2,3,6-trifluorophenol and pentafluorophenol), [M−H]− and [2M−H]− were the main products in high sample concentration. In low concentration [M−H]− and [M+Cl]− were the main products. In case of pentafluorophenol (PFP), in high temperature conditions the dimer was [2PFP−H]− instead of [2PFP+Cl]−. In conclusion, IMS has many advantages and application possibilities. It allows the rapid detection and continuous monitoring of volatiles directly from ambient air. IMS can also be used as a pre-separation technique in ambient mass spectrometry, without increasing the total analysis time remarkably. In IMS, it is also possible to study gas phase reactions in ambient conditions. Some of the IMS applications presented in this thesis could be developed further to be a permanent part of routine monitoring, analysis, and research work. For example, in the fundamental studies of phenols, the possibility to use updated versions of the instruments could improve the accuracy of the experiments. In addition, broader studies with several experimental conditions, would increase the possibility to develop the method further, especially in the monitoring of TATP, and building material and microbe emissions from the gas phase with AIMS.
Originalspråkengelska
Tilldelande institution
  • Helsingfors universitet
Handledare
  • Kauppila, Tiina, Handledare
  • Eiceman, Gary A., Handledare, Extern person
  • Kotiaho, Tapio, Handledare
Tilldelningsdatum15 dec. 2017
UtgivningsortHelsinki
Förlag
Tryckta ISBN978-951-51-3896-5
Elektroniska ISBN978-951-51-3897-2
StatusPublicerad - 15 dec. 2017
MoE-publikationstypG5 Doktorsavhandling (artikel)

Vetenskapsgrenar

  • 317 Farmaci

Citera det här