CP-3800 GC Operator’s Manual
115
to-carbon and phosphorus-to-carbon selectivity of the detector. The nitrogen-
to-phosphorus selectivity also may vary somewhat but the detector cannot
be tuned to respond to only nitrogen or only phosphorus.
Note:
When power is first applied to the TSD, the bead may require 2 to 3
minutes to re-light, i.e., stabilize the bead surface temperature and gas phase
reactions. If the bead does not re-light, check for other errors and review the
bead conditioning procedure and the bead optimization procedure.
Bead
Conditioning
This TSD bead probe requires additional conditioning to perfect detector
performance. Follow these recommended procedures to ensure maximum
lifetime and reliability of your TSD bead. Failure to follow these procedures
may result in poor performance and reduce TSD bead probe lifetime.
Each bead probe will have a particular bead current (i.e., bead surface
temperature) at which its gas phase chemistry will initiate. In order to operate
the detector, it is necessary to allow the bead to reach this ignition
temperature in a controlled manner. Attempting to accelerate this procedure
may decrease the lifetime of the TSD bead probe.
1
Check the position of the TSD bead in the detector tower. The TSD bead
must NOT make contact with the TSD collector screen. The bead should be
located in the center of the collector, with the collector positioned so that
both edges of the screen are equidistant from the bead.
2
Set gas flow rate (should be measured at the flame tip):
Air 175
mL/min
Hydrogen
4.0 mL/min
Carrier gas (+ make-up)
30 mL/min
3
Set temperatures:
Packed Column
175
°
C
Capillary Column 80
°
C (1 min), 20
°
C/min to 200
°
C (2 min)
Injector 230
°
C
Detector 300
°
C
4
Column oven temperature is accessed by pressing the Column Oven key
and entering the desired initial temperature. Injector temperature is set by
pressing the Injector key, selecting the injector to which your TSD column is
connected, and entering the desired temperature. Then page forward to
page 2 and check that the injector oven power is ON. Detector temperature
is set by pressing the Detector key, selecting the TSD, setting the detector
temperature to 300
°
, and turning the TSD Oven Power ON. Leave the
Electronics OFF at this point. Set the detector to range 12 and Autozero
OFF.
5
Allow the tower to reach temperature, and allow the bead to thermally
equilibrate for at least 15 minutes prior to turning on the bead power supply
by turning Electronics ON.
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