Agilent Technologies 5975T LTM GC/MSD, Troubleshooting And Maintenance Manual

Page: 37 / 270

Chromatographic Symptoms
3
Troubleshooting and Maintenance Guide 37
Contamination or Carryover
If your output has contamination or unexpected peaks, do the
following:
Isolate the source
1 Perform a solvent blank run using a new, pure source of
solvent. If the contamination disappears, the problem may
be either in the sample or solvent-related.
2 Perform a blank run (remove the syringe from the injector
and start a run). If the contamination disappears, the
problem is in the syringe.
3 Remove the column from the detector and cap the detector
fitting. Perform another blank run. If the contamination
disappears, the problem is in the inlet or column. If the
contamination remains, the problem is in the detector.
Check possible causes—all inlet and detector combinations
• Check the septum type and installation.
• Perform complete inlet maintenance: Replace all
consumable parts and bake out the inlet.
• Perform column maintenance: Bake out contaminants,
replace the inlet section of the guard column, and reverse
and bake out the column as needed.
• Check for sample carryover from previous runs. Make
several no-injection blank runs and see if the ghost peaks go
away or get smaller.
• Check the septum purge flow. If it is too low, the septum may
have collected contamination or condensate may be clogged
in the purge line.
• Check all gas trap indicators and dates.
• Verify the gas purity. Check for supply tubing and fitting
contamination.
• Verify that the LTM column program temperature and time
are sufficient for the samples being injected.
• Check the solvent level in the ALS wash bottles.
• Replace the ALS syringe if necessary.
• Check the sample injection volume.