Time-of-flight ion mobility spectrometry in combination with laser-induced fluorescence detection system

Abstract

A laser-induced fluorescence (LIF) was used as a complimentary detection system for time-of-flight ion mobility spectrometry (TOF-IMS). A LIF detection system is potentially faster than a conventional electrometer detector and can provide additional (to usual for IMS drift time) analytical information, namely wavelength of fluorescence maxima and fluorescence lifetime. Therefore, better discrimination ability can be expected. Additionally, the combination of IMS and LIF operates at atmospheric pressure. This allows fluorescence measurements of specified ions and ion clusters, which would not survive in a mass spectrometer. An IMS drift cell of open design with both the electrometer and LIF detectors was designed. The feasibility of IMS-LIF was demonstrated on the example of the Xanthene dye Rhodamine 6G (R6G). Electrospray was used as an ionization source. The release and desolvation of R6G ions from the electrospray with following IMS-LIF analysis were demonstrated. The effects of experimental parameters (e.g., ion gate and drift voltages, distance to ESI emitter) are demonstrated and discussed. The obtained results are promising enough to ensure the potential of LIF as a complimentary/alternative detection system for time-of-flight ion mobility spectrometry.

Ion Distribution Profiling in an Ion Mobility Spectrometer by Laser-Induced Fluorescence

“…In our experiments, Rhodamine 6G (R6G) was selected as the sample ion because its fluorescence characteristic in gas phase has been widely studied. − The sample was dissolved in methanol (Aladdin M116119 Shanghai, China) with a concentration of 0.5 mM. Electrospray ionization (ESI) was chosen as the ionization technique because it will not damage the fluorescence fluorophore of the sample. ,− The sample injector was driven by a mechanical pump (America KD Scientific, KDS Syringe Pump, America, Holliston Massachusetts) at a rate of 10 μL/min. The diameter of the ESI capillary was 75 μm, and the ionization voltage was 4500 V. Receiving.…”

UV Photoinduced Dynamics of Conformer-Resolved Aromatic Peptides

“…251 Finally, a proof of concept of hybrid experimental setups interfacing laserinduced fluorescence detection with ion mobility spectrometry has been established on rhodamine dye, which has the potential to address still open questions such as to which extent gas phase peptides ions retain their native structures. 252,253…”

“…Application of FRET to a gaseous protein GB1 (59 residues) has shown that the native structure of the protein, which is retained over a broad pH range (1.5–11), is disturbed in the gas phase as the charge state increases, revealing a Coulombic-driven unfolding and expansion of its structure . Finally, a proof of concept of hybrid experimental setups interfacing laser-induced-fluorescence detection with ion mobility spectrometry has been established on rhodamine dye, which has the potential to address still-open questions such as to what extent gas phase peptides ions retain their native structures. , …”

ABC Spotlight on Analytics 4.0

“…In automated situations as envisioned in the IoT this need is even greater and research for orthogonal detection strategies for the same analyte are in high demand. Uteschil et al have, for example, presented the combination of time-offlight ion mobility spectrometry (TOF-IMS) together with laser-induced fluorescence detection [2]; hence, spectroscopic and mass-based data are obtained during the same analysis. The authors demonstrate that this combination delivers not only more precise molecular information from IMS (i.e., the specific drift times) but also optical parameters such as fluorescence lifetimes or emission maxima, thus gathering simultaneous in-depth information on the analytes.…”