General Considerations For Tuning In Fi Mode; Lens Tuning - Waters GCT Premier Operator's Manual

14. Use a septum-piercing syringe, to inject approximately 5 µL
chloropentafluorobenzene into the reference reservoir.
See also:
15. Adjust the peak display to mass range 198 to 204 amu.
16. Right-click the peak display and click Intensity > Normalize Data.
17. Carefully adjust the micrometer until the peak at 201.9609 m/z is seen.
If the emitter is moved to far it may hit the GC column and become
damaged.
18. Use the beam steering and Focus 1, 2, and 3 values to optimize for
maximum intensity.
19. Carefully adjust the rotational adjustment knob on the emitter probe to
get the emitter wire as vertical as possible.
The rotational adjustment knob is very sensitive and must be adjusted
carefully.
20. Tune for best resolution by adjusting the Pusher Bias and the Grid 2
values.

General considerations for tuning in FI mode

Lens tuning

The focus lenses are interactive with the beam steering and combinations of
focus and steering settings can be used. The focus 1 lens often optimizes at
maximum negative voltages.
The tuning of the ion source is strongly dependent on the position of the
emitter with respect to the extraction rods the higher the field strength at the
emitter and the higher the sensitivity.
The position of the emitter with respect to the center line of the extraction
rods is also very critical. Small changes in this position can result in large
changes in beam steering voltage being required. In general, the beam
steering should be set close to zero and the emitter probe micrometer used to
optimize the signal. Small adjustments to the beam steering can then be made
using the beam steering lens.
Introducing the reference sample on page
General considerations for tuning in FI mode
9-21.
9-23