Varian 450-GC, User Manual

Page: 42 / 205

Installation
Varian, Inc. User Manual 450-GC Page: 23
Column Conditioning
In general the column should be conditioned at 20°C above the maximum
temperature used in the analytical method, or 20°C below the maximum
operating temperature of the column, whichever is lower. Check with the
column supplier for the correct conditioned details.
New Columns
To minimize chemical contamination of the detector, all new columns should be
baked out before they are connected to the detector. Refer to the supplier's
recommendations for temperatures.
Used Columns
Periodically (especially during extended isothermal operation), the column
should be baked out to remove accumulated contaminants. Column
conditioning is required when column efficiency begins to fall off, i.e. loss of
resolution, peak tailing, severely drifting baseline, retention of extra peaks, etc.
For fused silica columns, it is recommended that 1 to 2 turns at the beginning of
the column (approximately 1/2 meter) be cut off prior to reconditioning, as this is
the end part of the column where the stationary phase has most likely been
disturbed. Attach the column to the Injector and, with carrier gas flowing, bake
out the column for a minimum of 3 hours.
It is important to establish the maximum recommended conditioning
temperature for the installed column. This information is provided with the
column or can be obtained from the column manufacturer. The maximum
allowable temperature for the column does not have to be used for conditioning
purposes.
A GC column may be irreversibly damag ed if i t i s heated w it h air or
moistur e present in the pneumatic system. It is important to p urge the
column with inert carrier gas before heating the column. Af ter the
column f low is established, allow t he carrier gas to purge through t he
column for 15 - 20 minutes before heating it.