Contaminated Sample Ampule And Reference Gas Line; Contaminated Source Components - Waters Xevo TQ-GC Overview And Maintenance Manual

• Air leaks are often associated with the GC inlet. Ensure that any maintenance performed on
the GC is completed before carrying out any maintenance on the instrument.
• Ensure that the instrument and GC oven are regularly maintained.
• Use Mass Spec Check regularly to ensure the air and water ratios are acceptable.
• In EI mode, ensure that the vacuum is better than 5e-5 before putting the instrument into
Operate mode. This takes approximately 30 minutes.
Note:
In EI mode, MassLynx prevents you from putting the instrument into Operate mode
until the vacuum is better than 6e-5.
• In CI mode, ensure that the vacuum is better than 5e-5 before turning on the CI gas. Ensure
that the vacuum is continuously better than 8e-3.
Note:
In CI mode, MassLynx prevents you from putting the instrument into Operate mode
until the vacuum is better than 8e-3.
• Ensure that the GC interface column is fitted with the correct nut and ferrule, and tightened
appropriately.

5.3 Contaminated sample ampule and reference gas line

If the instrument has been operating in CI+ mode with a non-perfluorotributylamine (PFTBA)
reference gas and you change the instrument to operate in EI mode with PFTBA, you must use a
different reference gas ampule. Using the same ampule may contaminate the gas line and
invalidate the experiment.
For example, where an ampule was previously filled with 2,4,6-Tris(trisfluoromethyl)-1,3,5-
triazine, a residual 266 peak remains in the ampule, now-filled with PFTBA, and interferes with
the PFTBA 264 peak.
To avoid contaminating the reference gas line and invalidating an experiment, observe the
following best practices:
• Use a reference ampule specific to the reference gas being used.
• For CI+ operation, use the additional sample ampule provided containing 2,4,6-
Tris(trisfluoromethyl)-1,3,5-triazine.
• Ensure that samples and ampules are clearly marked to avoid mixing them up.
Note:
In the event of contamination, seek advice from your service contact.

5.4 Contaminated source components

Dirty or contaminated inner and outer source components can cause the following:
April 27, 2020, 715005564 Ver. 01 (previously released as Rev. A)
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