Chromatographic Symptoms 2
Agilent 7697A Troubleshooting 23
• For systems that have been exposed to long periods of
use with aggressive samples, consider whether the flow
path has been compromised. Replace flow path parts
as needed.
6 Check the transfer line connection to the GC inlet. Verify
the interface is hot. If using a split/splitless (or
multimode) inlet on an Agilent 7890A GC, try installing a
side inlet weldment accessory, G4556- 67070. This
accessory reduces unswept volume, allows easy ALS use
on the GC inlet, and reduces the chance for sample
condensation with at the transfer line to GC interface.
7 Check the reducer union where the transfer line connects
to the six port valve.
8 Check the HS sequence log, event log, and status displays
for messages. Especially check the sequence log for
method deviations related to vial pressure and purge flow.
9 Check HS method parameters.
• Check the purge flow and the standby flow. Try
increasing the purge flow (between sample vials) to
further eliminate residual sample in the sample loop,
probe, and related flow path. Try increasing the purge
hold time. Make sure that standby flow is enabled to
prevent contaminants from condensing in the sampling
system during periods of inactivity.
• Check the oven, loop/valve, and transfer line
temperature setpoints. The setpoints must be high
enough to keep the analytes volatile.
• Check the vial pressurization pressure and time.
10 After running the HS solvent blanks, if the carryover
decreases by a factor of 5 to 10 for each run, the
carryover is probably due to an unswept area in the flow
path.
If contamination exists in the six port valve, increase the
purge flow or purge time to sweep residual sample from the
system.
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