Agilent Technologies 7890A Troubleshooting Manual page 28

3
Chromatographic Symptoms
Contamination or Carryover
Isolate the source
Check possible causes—all inlet and detector combinations
28
If your output has contamination or unexpected peaks, do
the following:
Perform a solvent blank run using a new, pure source of
1
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 the septum type and installation.
• Perform complete inlet maintenance: Replace all
consumable parts and bake out the inlet.
• Perform column maintenance: Bake out contaminants,
remove the contaminated length of column near the inlet,
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.
• If you suspect that there is contamination in the inlet,
column, or detector, perform the bakeout procedure.
• Verify that the oven 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.
Troubleshooting