Outside of an ionization source and a Faraday plate, a drift tube IMS system is fundamentally comprised of 5 primary components:
- Reaction/Drift Cell
- Ion Gate
- Gate Pulsing Electronics
- Current to Voltage Converter
- Data Acquisition System (DAQ)
Within the IMS research community hardware and DAQ solutions are often custom and rarely replicated exactly. In an effort to address this knowledge and resource gap, the links posted below outline a range of solutions to the construction and operation of research-grade ion mobility spectrometers. It is our sincere hope that this information will be useful to other research groups and encourage others to make suggestions and improvements. The github links, including those from GAA Custom Engineering are found below:
Ion Gate Pulser
Current to Voltage Converter
WiPy DAQ System and GUI
The most recent poster presented ISIMS 2016 in Boston, MA can be found here: Clowers_ISIMS_2016_v5.
We are pleased to report the publication of our work outlining the effective coupling of a drift tube IMS system with an ion trap mass spectrometer. Compared to previous implementations (see our 2005 publication) we have dramatically improved the IMS duty cycle by encoding the mobility information in the frequency domain. Using this Fourier approach we can cover the full mobility spectrum in a fraction of the time that is typically required for a signal averaging technique. Perhaps most impressive from our perspective, is the ease of implementation. It is truly plug ‘N play with no hardware synchronization required. If anyone is interesting in more details regarding the pulsing hardware and parameters, you know where to find us.
Abstract: Historically, high pressure ion mobility drift tubes have suffered from low ion duty cycles and this problem is magnified when such instrumentation is coupled with ion trap mass spectrometers. To significantly alleviate these issues, we outline the result from coupling an atmospheric pressure, dual-gate drift tube ion mobility spectrometer (IMS) to a linear ion trap mass spectrometer (LIT-MS) via modulation of the ion beam with a linear frequency chirp. The time-domain ion current, once Fourier transformed, reveals a standard ion mobility drift spectrum that corresponds to the standard mode of mobility analysis. By multiplexing the ion beam, it is possible to successfully obtain drift time spectra for an assortment of simple peptide and protein mixtures using an LIT-MS while showing improved signal intensity versus the more common signal averaging technique. Explored here are the effects of maximum injection time, solution concentration, total experiment time, and frequency swept on signal-to-noise ratios (SNRs) and resolving power. Increased inject time, concentration, and experiment time all generally led to an improvement in SNR, while a greater frequency swept increases the resolving power at the expense of SNR. Overall, chirp multiplexing of a dual-gate IMS system coupled to an LIT-MS improves ion transmission, lowers analyte detection limits, and improves spectral quality.
We are pleased to announce the unpacking and, more importantly, the successful pump down of the G2. Combined with a new UPLC unit we anticipate this instrument playing a large role in future metabolomics work in our laboratory. Kudos to Justin Chang from Waters for executing the pump down sequence like a champ.
Unboxing to commence in t-minus 6 days and counting…
Comparison of CID and UV Photodissociation of Leucine Enkephaline Acquired at WSU.
In early 2015 the research group is pleased to bring the next generation ion mobility-ion trap system online. This system is equipped with two ion gates which allows the speed of the IMS to be effectively coupled to the slow scan speeds of traditional ion trapping experiments. Though not as fast as tradition IMS-TOF configurations, this experimental setup does allow multiple stages of CID and alternative modes of fragmentation such as UV and IRMPD. Another unique feature of this IMS system is that it can obtain IMS spectra using a standard Faraday plate and/or the LTQ.
Additional photos of the initial setup and UV beam line:
The ExcellIMS Dual Gate System smoothly mates to the LTQ.
Though a little difficult to see the IMS tube actually uses a square drift tube design with a nice set of BN gates.
Fully functional Dual-Gate IM-LTQ system.
193 nm Excimer Beam Line