Dc Polarity; Mass (Axis) Gain; Mass (Axis) Offset; Quadrupole Maintenance - Agilent Technologies 5975C TAD VL MSD Troubleshooting And Maintenance Manual

7
Analyzer

DC polarity

The DC polarity (DC Pol) parameter selects the orientation of the direct
current applied to the quadrupole mass filter. The DC polarity that works best
for your MSD is determined at the factory. It is listed on the final test sheet
accompanying your MSD. It is also listed on a label on the cover over the RF
coils. This cover can be viewed by removing the upper MSD cover.
Using the nonpreferred DC polarity may result in very poor performance. Always use
CA UT IO N
the factory-specified polarity.

Mass (axis) gain

Mass gain (MassGain) controls the mass assignment, that is, assignment of a
particular peak to the correct m/z value.
• A higher gain yields higher mass assignment.
• Mass gain affects peaks at high masses more than peaks at low masses.

Mass (axis) offset

Mass offset (MassOffs) also controls the mass assignment.
• A higher offset yields higher mass assignment.
• Mass offset generally affects peaks equally at all masses.

Quadrupole maintenance

The mass filter requires no periodic maintenance. It should not be removed
from the radiator. If
replacement), the quadrupole can be cleaned. Cleaning must be performed by
Agilent Technologies service personnel.
Never put the quadrupole in an ultrasonic cleaner.
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Never change the physical orientation of the quadrupole mass filter.
The fused-quartz quadrupole is fragile and will break if dropped or handled roughly.
The material in the cusps of the quadrupole is very hygroscopic. If exposed to water,
the quadrupole must be dried very slowly to prevent damage.
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absolutely
necessary (that is, if the only alternative is
5975 Series MSD Troubleshooting and Maintenance Manual