PerkinElmer CLARUS 600 GC, User Manual

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Clarus 600/680 User’s Guide
4-53
NOTE: ( 1) The bead will be stable after operating for several hours, but it will drift in time.
At the start of each day, adjust the background reading to the setting you are using
and allow a few minutes for it to stabilize.
(2) Due to the loss of alkali metal with use, the nature of the bead is to drift over time.
We strongly recommend using an internal standard for quantitative analysis.
(3) The bead can operate at higher background settings. The higher the setting, the
greater the signal and noise. Therefore, the signal to noise ratio will not increase
dramatically. Operate at the lowest possible setting to achieve the required sensitivity;
this will also prolong the life of the bead.
NOTE: The bead should be turned off by turning the bead potentiometer dial fully
counterclockwise before you turn off the Clarus GC. Remember that the bead has a
finite life. You can extend the bead life by turning the bead off when it is not in use
for long periods of time (for example, over the weekend).
Reactivate a Used NPD Bead
To increase the bead life, turn off the bead if the NPD is not continually in use.
When you turn off the bead, keep the detector temperature, hydrogen flow, and air
flow set to operating conditions. If the column remains connected to the injector
and detector in the oven, make sure the carrier gas is flowing through the column. If
the column is disconnected from the detector, make sure the Swagelok cap is
installed on the NPD fitting.
Prior to using the NPD, adjust the bead background to the same millivolt setting that
you were using. Run your standards to determine if the NPD bead is responding at a
level of sensitivity equal to the previous run. If not, then reactivate the NPD bead.
To reactivate a NPD bead follow the activation procedure above.
Operating Notes
The bead is operated as a conventional NPD bead; following these instructions will
increase the bead lifetime.
Baseline: Set the baseline to a level of between 0.4 – 0.5. A lower baseline will
help to extend bead lifetime. Studies have shown that the signal-to-noise will not be
adversely affected by the lower baseline.