Obtaining an ion beam 3-7
Tune window with peak display:
The peak at m/z 28 is air (nitrogen). The peak at m/z 219 is the heptacosa
reference sample. The aim of tuning the instrument is to maximize the sample
signal while keeping the nitrogen peak as small as possible. To accomplish
this, you can increase or decrease the beam steering and focus lens values.
See also: General considerations for tuning on page G-6.
As tuning improves, the reference mass increases in intensity. Reduce the
intensity of the reference sample by slowly opening the reference reservoir
valve. Aim to achieve about 1000 ion counts per second for the base peak of
the sample in continuum mode on the Tune window. This ensures that the
level of the sample peak is below the saturation level of the TDC.
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