Procedures For Manually Creating A Backflush Method - Agilent Technologies 7820A Advanced User's Manual

Procedures for manually creating a backflush method

Advanced User Guide
• Provides the ability to create pre-column backflush methods,
which require careful adjustment due to the elution times
and elution order differences found on pre-columns
(compared to the analytical column).
For more information, see the GC and GC/MS User Manuals &
Tools DVDs. In addition, the Backflush Wizard contains
extensive documentation.
To set up a post run backflush
A main advantage of the post-run backflush method is that the
GC turns off detection during this time. If using an MS, this
helps prevent damage to the detector and is the recommended
backflush method.
If using an Agilent data system, a Backflush Wizard provides a
straightforward interface for making these settings.
Verify that all columns are properly configured.
1
Since the backflush will run as a post-run program, set the
2
method so that the oven program ends after the last peak of
interest returns to baseline, or after reaching the last
temperature of interest.
Press [Post Run] and enter the backflush duration as the Time.
3
• The oven temperature and column pressure/flow
setpoints for installed columns appear.
• Whether you can enter a pressure or flow for a column
depends on its mode (pressure or flow).
4 Enter the oven temperature for the backflush.
5 Enter the backflush flow(s) or pressure(s).
If in flow mode:
• Enter a negative flow for the column connected between
the inlet and the CFT device. The GC will automatically
establish the corresponding pressures needed in the inlet
and the CFT device.
• Increase the flow rates in the column(s) connected
between the CFT device and the detector(s).
If in pressure mode:
• Set the pressure of the column connected between the
inlet and the CFT device to 0.000. This turns off flow from
the inlet.
4
Columns and Oven
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