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Installing 7890/7820/6890/6850 GC Columns
30
5975/5977 Series MSD Operating Manual
Columns
Many types of GC columns can be used with the MSD, but there are some
restrictions.
During tuning or data acquisition, the rate of column flow into the MSD should
not exceed the maximum recommended flow. Therefore, there are limits to
column length, diameter, and flow. Exceeding recommended flow results in
degradation of mass spectral and sensitivity performance.
Remember that column flows vary greatly with oven temperature. (See
Calibrate Column Flow Linear Velocity”
on page 46 for instructions on how to
measure actual flow in your column.) Use the Flow Calculation software and
to determine whether a given column will give acceptable flow with
realistic head pressure.
Conditioning columns
Conditioning a column before it is connected to the GC/MSD interface is
essential. (See
“To Condition a Capillary Column”
A small portion of the capillary column stationary phase is often carried away by
the carrier gas. This is called column bleed. Column bleed deposits traces of the
stationary phase in the MSD ion source. This decreases MSD sensitivity, and
makes cleaning the ion source necessary.
Table 5
Gas flows
Feature
Gas flows
High vacuum pump
Diffusion
Turbo
Optimal He column flow mL/min
1
1 to 2
Maximum recommended gas flow mL/min
*
* Total gas flow into the MSD: column flow plus reagent gas flow (if applicable). Based on helium gas
use. For other gases the maximum flow will vary.
1.5
4
Maximum gas flow, mL/min
†
† Expect degradation of spectral performance and sensitivity.
2
6.5
Max column id
0.53 mm
(30 m)
0.53 mm
(30 m)
CI and JetClean hardware capability
‡
‡ Operation in CI mode or with the JetClean option is not supported in OpenLAB CDS 2.1.
No
Yes