e-MSion strives to provide timely and professional service and support. We are currently expanding our network of third party service providers in North America and Europe.
You can the find answers to several FAQs below. Please contact our team with any additional questions you may have.
Frequently Asked Questions
e-MSion uses “ExD” to refer to the broad range of electron energies the ExD cell can produce. The ExD cell is capable of both low-energy (below 3 eV) electron capture dissociation (ECD) and high-energy (3-20 eV) electron-induced dissociation (EID).
In the literature, “ExD” refers to a family of electron-based fragmentation technologies including ECD, EID, electron transfer dissociation (ETD), electron detachment dissociation (EDD), and negative ion ECD (niECD). EID is also sometimes split into hot ECD (HECD) and electron-impact excitation of ions from organics (EIEIO), depending on the electron energy used.
See Qi and Volmer. 2017. Electron-based Fragmentation Methods in Mass Spectrometry: An Overview. Mass Spectrometry Reviews 36, 4-15.
e-MSion currently offers a commercial ExD solution for Agilent LC/Q-TOF and Waters SELECT SERIES™ Cyclic IMS mass spectrometers.
Contact us if you are interested in becoming an early adopter of ExD for a mass spectrometer belonging to the Thermo Fisher Q Exactive Orbitrap™ series or the Waters SYNAPT™ G2 series.
Please contact e-MSion directly for service and support inquiries.
Including time for unpacking, venting, pump down, and performance verification, a field service engineer will typically require 2 days to complete the installation process. Hardware modification takes about 30 minutes.
Please contact us to learn more about installation requirements.
The ExD cell operates on a microsecond timescale. Its high speed and flow-through design means that the instrument duty cycle is unaffected by installation of the cell.
The ExD cell electron source is a consumable filament, which requires replacement after burning out. Several features in the ExD Software are designed to extend the filament lifespan by protecting it from rapid heat changes.
Filament replacement involves swapping out “plug-in” filament cassettes inside the cell, which minimizes the time spent with the instrument vented and the subsequent pump down time needed before the instrument is operational again. We provide users with instructions for replacing the filament in our product documentation.
Unlike ETD, ECD does not use any reagent. This combined with its distance from the source means the ExD cell does not require regular cleaning.
Use the ExD Software to change ExD cell settings. The same settings for ECD will work on most analytes with minimal adjustment. See Technology for a description of ExD cell operation.
Currently, the ExD AQ-250 Option for Agilent LC/Q-TOF offers an autotune feature for simplified use. Autotuning for our other products is under development.
Due to its flow-through design, the ExD cell operates at a speed compatible with HPLC, UPLC, CE, and IM separation methods.
The ExD cell is designed to fragment polypeptides, but can also be tuned to fragment glycans and lipids.
ECD efficiency theoretically increases with the square of ion charge, making the ExD cell more efficient at fragmenting large, multi-charged proteins. In practice, noncovalent interactions limit the ability of ECD alone to dissociate folded proteins larger than ~30kDa. Denaturing conditions and/or supplemental vibrational excitation can be used to increase ECD efficiency of larger proteins.
On the other end of the spectrum, the ExD cell is capable of fragmenting short peptides, albeit with lower efficiency. For ECD, a minimum precursor charge of 2+ is required to detect product ions because of the charge neutralization that occurs with electron capture.
The ExD cell can also be tuned for EID to target singly charged precursors and non-peptidic samples. This technique is currently only useful for applications where sample quantity is not limited. Development to increase EID efficiency is ongoing.
At some point, you or your service engineer may want to temporarily revert the instrument to its default hardware configuration. The “swap-out” design of the ExD cell makes this possible, since all original parts are preserved during installation.