Following up on previous post, we’ve finally released a major update to the Open Source IMS Initiative. Appearing now in Hardware X we detail a new modular IMS design that is extremely flexible. Three of our ASMS 2018 posters feature data from these system and the are proving an invaluable new tool to our research infrastucture. Though the current systems are limited to lower temperature operation (i.e < 120 °C), the designs are readily adapted to Rogers material which is quite robust well above 200 °C. Another key adaptation making this design tractable is the new ion shutter design which uses 3 grids to create a set of well defined ion pulses. Though the BN-gates are attractive in that the physical structure is in a single plane, their construction is an art. Moreover, the fields established by the BN gates are also, by no means, fully planar. With the new design we can achieve that smooth field in the region surrounding the ion gate and still get extremely small ion gate pulse widths (i.e < 20 μs). If you are interested in some of the core details or have suggestions for improvement, come find us on github: https://github.com/bhclowers/OS-IMS
Ion gating remains a critical aspect of drift tube IMS experiment and a range of clever approaches have been used the past. However, most techniques use a physical grid to modulate the ion beam. In collaboration with Steve Kenyon and Keith Gendreau we’ve adapted a modulated x-ray source to printed circuit board IMS. Though there is still room for improvement, the initial results look quite promising. Interestingly, because the source is now located orthogonal to the drift axis, a new term is added to the descriptors of peak width. What we’re most excited about, however, is the fact that because we no longer have a physical ion gate, some of the capacitive coupling during the pulsing of a standard ion gate is now effectively eliminated–enter artifact-free multiplexing…
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 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.
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
Recently, we brought two CTC PAL systems on-line in the group and in an effort to save a little bit of money* and explore the utility of 3D printing we engaged the engineering department at WSU to print out a sample trays that was compatible with the PAL system. Granted the result doesn’t have the fancy vial numbers (nor did we try) but the result was quite pleasing. 3D printing still isn’t dirt cheap when you factor in the time but at least for this application the trays were a significant break compared to the commercial version.
In case there are others that are interested, the stl and sldprt files are here: PAL_Tray
*sure the cost of the PAL vastly exceeds the cost of single tray but every little bit counts at this stage.
The Clowers Research Group is now live. Reporting in are the background ions from ionized air measured using a residual quadrupole gas analyzer and the LeCroy “Panzer” oscilloscope. These data are to help monitor background gases in the high vacuum chamber (not shown) and provide diagnostic support for gases ionized by the excimer laser (also not shown). With a little luck, laser beams are next week. Stay tuned…
Why Oscilloscope Bandwidth Matters: A big part my New Year’s Resolution to improve my overall design process was better testing. Better testing is an important part of better and more intentional design, but it means having tools that you can trust and that can consistently give you the results you need. – http://www.adafruit.com/blog/?p=23753