13 Detector
13.3 Thermal conductivity detector (TCD)
162
GC-2010 Plus
SIGNAL POLARITY
Selection: +/-, Default: +
When analyzing compounds with a thermal conductivity higher than the carrier gas,
baseline peaks are inverted (negative). When this occurs, switch to a polarity of “-” to
produce positeve peaks.
CURRENT
Range: 0−100 mA, Default: 0 mA
The TCD sensitivity is approximately proportional to the cube of the current.
If the sensitivity is insufficient, increase the current within the range shown in Fig.
13.3.3. The maximum operating current is determined by the detector temperature and
the carrier gas type. Keeping the current highre than necessary shortens the filaments
life and can cause baseline drift.
Fig. 13.3.3 Maximum operating current
CAUTION
If the current is turned on before the carriergas + make up gas has
completely replaced the air, the filament can be blown.
Ensure that the current is set to “0” at first. Press the [SYSTEM] key
and select the [start GC] (PF menu), set the start time to approxi-
mately 10 minutes. Ensure that the carrier gas flows out frow the
detector vent before setting the current.
CAUTION
To avoid broken filaments and poor performance, set the current
below the valves indicated by the curves below.
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