High Noise Levels In Mrm Analyses - Waters Xevo TQ-GC Overview And Maintenance Manual

Table 6–8: Poor resolution
Possible causes
Dirty lens stack or prefilters, giving small peaks
on either side of the main peak.
Ion energy set too high, or repeller not
optimized, giving broad peaks with jagged
tops.

6.2.9 High noise levels in MRM analyses

The following table lists the corrective actions for the two types of noise in MRM analyses.
Table 6–9: High noise levels in MRM analyses
Possible causes
Electronic noise.
Chemical noise.
April 27, 2020, 715005564 Ver. 01 (previously released as Rev. A)
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Corrective actions
Vent the instrument (see
instrument for working on the
clean the outer source lens stack (see
Cleaning the outer source assembly's lenses
and spacers). If the peak resolution does not
improve, contact Waters.
Reduce the ion energy, or adjust the source or
repeller voltage.
Corrective action
Ensure that, when ion energies are fully
negative, the valleys of the peak-to-peak noise
just touch the baseline. If necessary, increase
the Ion Counting Threshold.
Inspect for dirty gas lines or contaminated
samples, solvents, or GC or CI reagent gases.
Preparing the
source), and