Yokogawa GC8000 Process Gas Chromatograph - Manual (Page 481)

<Appendix E Computation Scheme>
App.E-8
IM 11B08A01-01E
• The analysis elapse time is greater than the gate-on time.
• The previous peak is ended.
• The detector signal exceeds the detection level.
• The gradient of the detector signal (change with time) exceeds the peak-on detection slope
value.
When all the following conditions are satisfi ed, it is assumed that the peak is ended (off):
• The analysis elapse time passes the gate-off time.
• The detector signal passes the peak point.
• The detector signal is lower than the detection level.
• The gradient of the detector signal (change with time) is smaller than the peak-off detection
slope value.
If the next gate is started before the detector signal passes the peak point, it is also assumed that
the peak is ended (off).
The detection level can be set for each peak based on the signal level upon the start of analysis
(or the base level when the base level setting is specifi ed).
The peak-on detection slope value is equal to the detection slope value (set for each peak).
The peak-off detection slope value is the detection slope value multiplied by the detection slope
on/off ratio (that can be group-set).
F0205020104.ai
Peak-on detection
slope value
Peak-on detection slope value
Base level
Peak
gate
(e) Zone Gating
Zone gating method detects peaks under the upper limitation of specifi ed number of peaks in the
range (zone) between the gate-on time and the gate-off time.
(i) Peak detection action in zone gating
The peak detection action in the zone gating acquires the number of peaks assigned to the zone
using the gate on as a trigger and like the regular slope detection, starts the detection of peak on.
As soon as the peak on is detected, the detection of peak off is started. At the point the peak off is
detected, the fi rst peak is determined.
The following peak detection is started and then the second and third peaks are determined. This
peak detection action is continued until the peaks of assigned number are determined. After the
detection of the fi nal peak in the zone has been completed, the peak detection is not performed
until the gate-off time.
2nd Edition : May 11, 2012-00