Yokogawa GC8000 Process Gas Chromatograph - Manual (Page 480)

<Appendix E Computation Scheme>
App.E-7
IM 11B08A01-01E
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According to the change in the retention time of each peak that is specifi ed as standard, the
gate time of the specifi ed peak and processing time of the specifi ed signal level are changed.
When only one standard peak is specifi ed, the gate time and processing time are obtained in
proportion with the retention time. When two or more standard peaks are specifi ed, the gate time
and processing time are obtained for each peak by performing a linear approximation on the fi rst
peak and the last peak.
The variation coeffi cient of the obtained retention time is shared by all peaks.
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Initial chromatogram
Initial gate
Initial gate
Initial chromatogram
Chromatogram after change
Gate after tracking processing
Standard peak
(c) Time Gating
Time gating processing detects peaks within the predefi ned time interval when the following
condition is satisfi ed:
The detector signal value is higher than the detection level within the range between the specifi ed
gate-on time and gate-off time.
The detection level can be set for each peak based on the signal level upon analysis start (or the
base level when the base level setting is specifi ed).
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Base level setting
Detection level
Detection level Base level
Base level
Peak Peak
Gate Gate
(d) Slope Gating
Slope gating processing detects peaks based on the change in the time of detector signal
data. The time when detection is started is predefi ned as the gate time. When all the following
conditions are satisfi ed, it is assumed that the peak is started (on):
2nd Edition : May 11, 2012-00
App.E