5 Micro GC Channels
Tuning the backflush time on a HayeSep A channel
78 Agilent 990 Micro GC User Manual
Tuning the backflush time on a HayeSep A channel
For each new HayeSep A channel with a backflush option, it is necessary to tune the backflush
time properly. The tuning procedure of the HayeSep A channel is different than the tuning
procedure of other channels.
The goal for tuning the backflush time for the HayeSep A channel is to get all peaks of interest,
components up to propane, on the HayeSep A column while all unwanted peaks that elute after
propane are backflushed.
Tuning procedure for HayeSep A channel
1 Set the backflush time of the HayeSep A channel to 0 seconds.
2 Set an appropriate run time for the first analysis (for example 300 seconds or longer).
3 Analyze the NGA Gas Calibration standard, and identify all components in the calibration
standard.
4 When all peaks of interest are identified, select a proper backflush time after propane peak.
Figure 30 shows an example of the tuning procedure of HayeSep A channel. In this example, the
propane peak elutes around 90 seconds, proper backflush time for the HayeSep A here is around
120 seconds.
Consider that the total run time must be sufficient to backflush all unwanted components from
the column. The ideal total run time is approximately twice the backflush time or higher. So in this
example, a total run time of 240 seconds is sufficient to backflush all unwanted components from
the HayeSep A channel.
To disable backflush
To disable backflushing, set the backflush time to 0. This puts the system in normal mode during
the entire run.
Figure 30. Selecting backflush time for a HayeSep A channel
Seconds
10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170
mVolt
20
40
60
80
100
Carbon Dioxide
Ethane
Propane
i--Butane
Nitrogen
Methane
Peaks of Interest
Appropriate
Backflush Time
Unwanted Peak
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