Thermo Scientific
MS/ETD System Getting Started Guide
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Introduction
The LTQ XL/ETD and LTQ Velos/ETD systems are members of the Thermo Scientific
family of mass spectrometer (MS) detectors, and consist of an ETD module installed at the
back of an LTQ XL or LTQ Velos MS detector. With the LTQ XL/ETD or LTQ Velos/ETD
system you can perform electron transfer dissociation (ETD) mass spectroscopy on analytes.
The LTQ XL and LTQ Velos MS detectors are advanced analytical instruments that include
an atmospheric pressure ionization (API) source, a divert/inject valve, a linear ion trap, a
syringe pump, and the Xcalibur data system.
The MS/ETD System is a source of fluoranthene reagent ions that react with analyte
molecules in the linear ion trap of the LTQ XL or LTQ Velos MS detector. The ETD module
contains two reagent vials, chemical ionization (CI)/carrier gas (nitrogen) handling hardware
and flow restrictors, ion volume and filament, ion optics, and heaters for these components.
The flow restrictors keep the internal pressure of the reagent vials below atmospheric pressure
which prevents the contents of the reagent vials from being expelled into the laboratory
atmosphere.
The nitrogen gas serves two functions in the ETD process. It is both a carrier gas and a CI
vehicle. As a carrier gas, the nitrogen sweeps the reagent from the vial to the ion source where
reagent radical anions are formed.
As a CI vehicle, the nitrogen gas collides with 70eV electrons from the filament in the ion
volume. These 70eV electrons from the filament knock electrons from the nitrogen
molecules, creating nitrogen ions. The secondary electrons resulting from these collisions have
near thermal kinetic energies. The fluoranthene captures these thermal electrons to form
reagent radical anions. The ETD optics transport the reagent radical anions to the linear ion
trap where they react with the analyte.
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Electron Transfer Dissociation
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