Yokogawa GC8000 Process Gas Chromatograph - Manual (Page 483)

<Appendix E Computation Scheme>
App.E-10
IM 11B08A01-01E
 Coexistence of slope/time method with regular peak detection actions
Like the slope gating, time gating and zone gating method, the slope/time method is
performed by setting at the peak unit. Therefore, the slope/time method is considered as
one of the regular detection actions, allowing it to coexist with other detection methods in
one stream.
(g) Time/slope Method
Unlike the usual slope detection method or time gating method, time/slope method performs a
peak detection by using the time gating method for the peak on detection and the slope detection
method for the peak off.
 Coexistence of time/slope method with regular peak detection actions
Like the slope gating, time gating and zone gating method, the time/slope method is
performed by setting at the peak unit. Therefore, the time/slope method is considered as
one of the regular detection actions, allowing it to coexist with other detection methods in
one stream.
 Peak Waveform processing
This is the same as in peak waveform processing in Manual mode. (See Section 2.3.2.)
However, area calculation by tangent skimming or vertical separation can be specifi ed for each
peak.
 Concentration Computation Processing
Concentration is computed when level processing for the last peak is completed in each stream.
Corrected area normalization or the standard method (external standard of indirect method) can
be group-specifi ed in the stream common list.
(a) External Standard (Approximation by Cubic Equation)
The external standard (approximation by cubic equation) computes concentration from the area
value based on the predefi ned coeffi cient.
The specifi ed standard peak is used for the coeffi cient α, S
b
, R, K, A and B.
The computation formula is:
C = RK(αS
i
/S
b
) (A (αS
i
/S
b
) 2 + B(αS
i
/S
b
) + 1)
Where:
C : concentration
α
: calibration factor
S
b
: standard area (or height)
S
i
: measured area (or height)
R : measurement range
K : coefficient
A : coefficient
B : coefficient
(b) External Standard (Approximation by Linear Equation)
The external standard (approximation by linear equation) calculates a coeffi cient of the linear
equation from the area (or height) of two peaks specifi ed as standard peaks specifi ed as
standard peaks and calculates the concentration from the area (or height) measured using the
coeffi cient.
The equations are as follows.
(1) During
calibration
During calibration, if the range of the calibration coeffi cient is zero, calculate the standard
area, if specifi ed, calculates the calibration coeffi cient.
2nd Edition : May 11, 2012-00