
8
CI Maintenance
To Clean the CI Source
7000/7010 Series TQ GC/MS Operating Manual
233
.
Procedure
1
If the contamination is serious, such as an oil backflow into the analyzer,
seriously consider replacing the contaminated parts.
2
Abrasively clean the surfaces that contact the sample or ion beam.
Use an abrasive slurry of alumina powder and reagent-grade methanol on a
cotton swab. Use enough force to remove all discolorations. Polishing the
parts is not necessary; small scratches will not harm performance. Also
abrasively clean the discolorations where electrons from the filaments
enter the source body.
3
Rinse away all abrasive residue with reagent-grade methanol.
Make sure
all
abrasive residue is rinsed
before
ultrasonic cleaning. If the
methanol becomes cloudy or contains visible particles, rinse again three
times.
4
Separate the parts that were abrasively cleaned from the parts that were not
abrasively cleaned.
CAUTION
If the CI lens insulator is dirty, clean it with a cotton swab dampened with
reagent-grade methanol. If that does not clean it, replace it. Do not abrasively
or ultrasonically clean this insulator. Do not attempt to clean other ceramic
insulators in the source.
Figure 78.
CI source parts to be cleaned
Entrance lens
Ion focus lens Drawout cylinder
Drawout plate
Source body
Repeller