| This thesis describes the use of ion mobility spectrometry (IMS) coupled to time-of-flight mass spectrometry (TOF-MS) for examining electrospray-generated (ESI) ions. Two versions of ion mobility spectrometers were used, a conventional low field drift tube IMS and the new technology called high-field asymmetric-waveform ion mobility spectrometry (FAIMS).; A commercially-available drift tube ion mobility spectrometer was interfaced to a laboratory-built linear TOF mass spectrometer. The system was evaluated with small molecules including tetraalkylammonium ions, and with larger ions including the multiply-charged ions of proteins. Their low resolution ion mobility spectra typically comprised two peaks; one peak yielded characteristic electrospray ions while another of lower mobility did not. The TOF mass spectra of protein at the lower IMS cell temperature (30°C) showed signs that were characteristic of protein-solvent clustering. The degree of solvation decreased with increasing IMS temperature. The mobility observed in IMS spectra and the charge state distributions seen in TOF mass spectra were somewhat dependent on the solution composition. This system could also be used for determination of cross-sections of gas phase protein ions generated by electrospray ionization. The dependence of ion mobility on ion cross-section was used to calculate cross-sections for ubiquitin, cytochrome c, myoglobin, lysozyme and α-lactalbumin ions. Disulfide-intact proteins, lysozyme and α-lactalbumin, were studied in the disulphide-intact and the disulphide-reduced states. The cross-sections ranged from approximately 1609 ± 80 Å2 for native lysozyme to approximately 4768 ± 238 Å 2 for denatured myoglobin and generally increased with the number of charges on the ion.; A newly-developed device called high-field asymmetric-waveform ion mobility spectrometer (FAIMS) with a cylindrical geometric configuration that utilized an ion separation technique based on the change in ion mobility at high electric fields, and which focused ions in two dimensions, has been revealed recently. This thesis describes a version of the FAIMS device in which this focusing was extended to 3-dimensions (i.e., ion trap). A method for the 3-dimensional confinement of ions with mass spectrometric interesting at 760 Torr and room temperature has not been described previously. With this system, several experiments have been conducted showing the trapping of low-mass water cluster ions, high mass ions generated by corona discharge and multiply-charged protein ions generated by electrospray ionization technique. The experimental results reported in this thesis indicate that FAIMS is a new generation of simplified, high sensitivity technology. (Abstract shortened by UMI.)... |
