Setting Npd Adjust Offset On The Clock Table; Aborting Npd Adjust Offset; Extending The Npd Bead Life - Agilent Technologies 7820A Advanced User's Manual

Setting NPD adjust offset on the clock table

Aborting NPD adjust offset

Extending the NPD bead life

Advanced User Guide
Detector on and ready. When the Adjust offset value is reached,
the Adjust offset line reads Done and displays the offset target
setpoint. Your detector is on and ready. The display shows the
actual Bead voltage.
You can use the Clock table feature to begin Adjust offset at a
specified time.
Press [Delete] with the cursor on the Adjust offset line. This
cancels the adjustment without turning off the detector gases
and bead voltage.
These actions, together with the automated heatup and adjust
procedures, can extend ceramic bead life considerably.
• Use the lowest practical Adjust offset value. This will result in
a lower Bead Voltage during operation.
• Run clean samples.
• Turn the bead off when not in use.
• Keep the detector temperature high (320 to 335 °C).
• Turn the hydrogen flow off during solvent peaks and
between runs.
Turning hydrogen off during a solvent peak
When using the NPD, the baseline shifts after a solvent peak and
can take some time to stabilize, especially with chlorinated
solvents. To minimize this effect, turn off the hydrogen flow
during the solvent peak and turn it back on after the solvent
elutes. With this technique, the baseline recovers to its original
value in less than 30 seconds. This also extends the life of the
bead. The hydrogen can be turned on and off automatically as
part of a Run Table. See
Turning hydrogen off between runs
To extend bead life, turn off the hydrogen flow between runs.
Leave all other flows and the detector temperature on. Turn on
the hydrogen flow for the next run; the bead will ignite almost
immediately. The process can be automated with Run Table
entries.
"Run Time Programming"
5
Detectors
on page 12.
93