Selecting Reference And Makeup Flows For The Tcd; Chemically Active Compounds Reduce Tcd Filament Life - Agilent Technologies 7890 Series Advanced Operation Manual

5
Detectors
Makeup gas flow, mL/min
Pressure (psig)

Selecting reference and makeup flows for the TCD

Chemically active compounds reduce TCD filament life

178
20
16
12
8
4
10 20
69 138
(
kPa)
Table 45
Gas type
Carrier gas
(hydrogen, helium, nitrogen)
Reference
(same gas type as carrier)
Capillary makeup
(same gas type as carrier)
Detector temperature
<150 °C, cannot turn on filament
Detector temperature should be 30 °C to 50 °C greater than highest oven ramp
temperature.
Sample components with higher thermal conductivities than
the carrier gas produce negative peaks. For example, helium
or hydrogen form a negative peak with nitrogen or
argon- methane as the carrier gas.
The tungsten- rhenium TCD filament has been chemically
passivated to protect against oxygen damage. However,
chemically active compounds such as acids and halogenated
Hydrogen
Helium
Nitrogen
30 40
207 276
Recommended flow rates and temperatures
Flow range
Packed, 10 to 60 mL/min
Capillary, 1 to 5 mL/min
15 to 60 mL/min
See the figures to select a value.
5 to 15 mL/min—capillary columns
2 to 3 mL/min—packed columns
50 60
345 414
Advanced Operation Manual