204 5977B Series MSD Troubleshooting and Maintenance Manual
7 Analyzer
AMU gain
AMU gain (AmuGain) affects the ratio of DC voltage to RF frequency on the
mass filter. This controls the widths of the mass peaks.
• Higher gain yields narrower peaks.
• AMU gain affects peaks at high masses more than peaks at low masses.
AMU offset
AMU offset (AmuOffs) also affects the ratio of DC voltage to RF frequency on
the mass filter.
• Higher offset yields narrower peaks.
• AMU offset generally affects peak widths equally at all masses.
219 width
m/z 219 is a prominent ion near the middle of the mass range of PFTBA. The
width parameter (Wid219) makes small corrections to the m/z 219 peak width.
Amu gain and amu offset must be readjusted after the 219 width is changed. If
you are tuning with a compound other than PFTBA, there may not be an ion at
m/z 219. In that case, set the 219 width to the last value found for it by
Autotune, or set it to 0.
Figure 48 Quadrupole mass filter
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