Recent Publication: Mobility Separation and UVPD of Co-Adducted Tetrasaccharides


Ultraviolet photodissociation (UVPD) has had its application directed primarily at biomolecule analysis, but with a common drawback of low fragment abundances. We encountered this same problem with UVPD of two sodiated isomeric glycans, but found a significantly higher fragment yield from the cobalt adducts of those same tetrasaccharides. An additional bonus was that the cobalt adduction increased the resolution of the isomers from no discernible mobility separation as sodium adducts to a resolution of 0.78. This allowed us to use UVPD for fragmenting a mobility separated mixture of the two glycans, which benefited from the higher fragment yield of the cobalt adducts.

Paper Link:

Recent Publication: Enhanced Mixture Separations of Metal Adducted Tetrasaccharides


Using a combination of Fourier transform ion mobility and ion trap mass spectrometry Kelsey demonstrated the degree to which different metal cations were able to enhance isomer separations across a set of tetrasaccharides.  While full resolution was not achieved for the full set of 5 isomers this work demonstrates the current state of the art for true isomeric mixture separations using IMS.  Another interesting aspect of this work was the observation of metal cation bound dimers.  Though we couldn’t tell whether they were homo or heterodimers we’ve now obtained a deuterated set of isomers which will help to answer that question.

Paper Link:


Open-Source, Modular Approaches to Ion Mobility Spectrometry

Pulse_Comp_v3Outside 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.

Fourier Transform Ion Mobility-Ion Trap Mass Spectrometry


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.

Dr. Clowers Recognized for Early Career Achievement

In the Spring Semester of 2015, Dr. Clowers was recognized within the College of Arts and Sciences at Washington State University for Early Career Achievement.  The College of Arts and Sciences celebrated achievements in teaching, research, and mentoring at its third annual Appreciation and Recognition Social on April 22, 2015.  Dr. Clowers was one of the nineteen faculty and staff, and six graduate students from across the college who were honored for their contribution to the WSU community and their commitment to excellence.


Live from Fulmer Hall: Waters G2

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.  IMG_2148



IMS – Ion Trap Equipped with UV Photofragmentation


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