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5
Micro GC Channels
Backflush to Detector
Backflush to Detector
Backflush to detector is an advanced technique to elute high boiling point compounds as a group
through the reference column, and show as one peak on the chromatogram just before the low
boiling point compounds. The benefit of this technique is that the analysis time is reduced. In
some cases, the analysis could even be done on just one channel.
The Agilent 990 Micro GC offers two types of backflush to detector channels. A CP-Sil 5 CB for
natural gas analysis and Al2O3 for refinery gas analysis. The backflush to detector channel is
factory tuned to group the C6+ components.
CP-Sil 5 CB Backflush to detector
The CP-Sil 5 CB backflush to detector micro GC channel is configured with an 8 m CP-Sil 5 CB
analytical column and a 0.5 m CP-Sil 5 CB precolumn. It elutes C6+ in natural gas as one peak
through the reference column, and shortens analysis time to 90 seconds. It is compliant with
GPA2172 for calorific value calculation.
Al2O3 Backflush to detector
The Al2O3 back flush to detector micro GC channel is configured with a 10 m Al2O3/KCl analytical
column and a 1 m CP-Sil 5 CB precolumn. It elutes C6+ in refinery gas as one peak through the
reference column, and shortens analysis time to 210 seconds.
System
pressure
Pressure
regulator
Figure 31.
Backflush to detector flow
Agilent 990 Micro GC User Manual
Restriction
Precolumn
Injector
Analytical
column
Pressure point
Reference
column
Detector
79
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