Running An Fd Experiment Using The Probe Ramp - Waters GCT Premier Operator's Manual

2. Set up the manual experiment as required, ensuring data is collected in
continuum because signals are normally leak in FD..
3. In the MassLynx Tune window FD tab, increase the Emitter Current
This will gradually warm up the emitter and desorb the sample. As it is
desorbed the sample will ionize on the emitter.
4. In the Tune window, monitor the spectrum as the acquisition
progresses. It is recommended that the sample is desorbed slowly.
5. At the emitter current where ions are seen in the spectrum a large
increase in signal for a small increase in emitter current may occur.
6. Increase the Emitter Current in small increments allowing the signal
intensity to stabilize each time the current is increased.
Caution:
thermal degrading of the analyte on the emitter surface before
ionization, reduced overall ionization efficiency and in severe
cases arcing between the emitter and the extraction rods due to
localized increases in pressure.
7. When the signal drops to a low value you can then resume raising the
Emitter Current.
Once all the sample has been desorbed from the emitter, flash off the
emitter by raising the emitter current.
Increase the Emitter Current to 100 µA for five seconds then dropping it
8.
back to zero.
The acetone peak should be clearly visible again and the acquisition may
be stopped.
Note: For some analyses it may be preferable to ramp the emitter
without acetone in the source. With no reference material in the source
there will be more sites available for ionization of the sample. In this
case use acetone initially, to tune and then pump out the reference
reservoir before commencing the ramp. However, acquiring without a
lock mass increases the error of the accurate mass measurement.

Running an FD experiment using the probe ramp

If a controlled ramp is desired for the emitter current then this can be set in
MassLynx Probe Control dialog box. The Probe Control is set up in the same
9-30 FI/FD Operation
Increasing the emitter current too quickly can result in