16
Installation
The test chromatogram accompanying your TCD was obtained under the
following conditions:
Sample:
~100 ppm blend in Helium balance
Sample volume:
250 µl
Column:
10' x 1/16" x 0.040" molecular sieve 5Å micropacked
Column flow:
6 mL/min
Reference flow:
6 mL/min
Column temperature: 65°C
Detector temperature: 100°C
Filament temperature: 230°C (a setting of 5.0)
Carrier gas:
Helium
Balancing the Channels
using LCD Display
The LCD display indicates the signal level from the recorder/chart output.
10. Set the recorder switch to A, and use the coarse and fine controls for
Channel A to adjust the signal level to about 300 mv.
11. Set the recorder switch to B and repeat the same process to adjust the
signal level to about 200 mv.
12. Set the recorder switch to A-B. The display should read about 100 mv. If
the signal levels drifts below zero, readjust the A & B channels.
The detector is now ready for analytical use.
Balancing the Channels
using Recorder/Chart Output
10. Use the zero (or shunt) setting on the recorder to set the true zero on the recorder.
11. Set the Recorder switch to A, and use the coarse and fine zero controls
for Channel A to bring the recorder pen on scale and to a position
approximately 1-2 cm above zero.
12. Set the Recorder switch to B, and repeat the same process, bringing the
pen to a position
half as far above zero as the pen for Channel A.
13. Set the Recorder switch to A - B, and observe the recorder pen position.
It should be above the true zero position, but below the position for
Channel A. If the pen drifts below zero, readjust the A and B channels.
The detector is now ready for analytical use.
Balancing the Channels
using Unattenuated Outputs
10. Connect the output cable to the A connector, and use the coarse and fine
zero controls for Channel A to bring the baseline signal on scale and to a
position approximately 100 mV above zero.
11. Move the output cable to the B connector, and use the coarse and fine
zero controls for Channel B to bring the baseline to a position half as far
above zero as for Channel A (the value of A minus B).
12. Move the output cable to the A - B connector, and observe the baseline
signal. It should be above the true zero position. If the signal drifts below
zero, readjust the A and B channels.
The detector is now ready for analytical use.
Single filament mode
The basic procedures and temperature settings described for referenced
mode operation can also be applied to operation in the single filament or
independent mode. Both channels must have the same carrier gas; you
cannot use helium carrier in one channel and nitrogen in the other. Also be
aware of the possibility of detector cross-talk when components elute from
the columns in concentrations greater than 1%.
