Yokogawa GC1000 Mark II Process Gas Chromatograph - Manual (Page 17)

1-2
<Toc> <Ind> <1. Principle of Gas Chromatograph >
IM 11B03A03-01E 3rd Edition : Aug. 23. 2006-00
1.2 Component Separation Using Column
Three types of columns are available for the GC1000 Process Gas Chromatographs: the
packed column, the mega-bore column and the capillary column.
The packed column consists of a stainless pipe, 2 mm in diameter and 0.2 to 2.0 m in
length and filled with a bulking agent called a stationary phase.
The mega-bore and capillary columns, of approximate diameter 0.5 mm and 0.3 mm
respectively, are coated inside a certain phase called a stationary phase.
The components in the multi-component gas mixture sample with carrier gas, which called
mobil phase move through the column, repeatedly absorbing the stationary phase and
dissolving from the stationary phase at a certain cyclic rate conforming to a fixed partition
coefficient * that is unique to each component.
Since the transfer rates differ depending on the partition coefficient, a multi-component gas
mixture gradually separates into discrete components and is separated in the order of the
transfer rates.
* Partition coefficient : The concentration ratio of the components, calculated by dividing the component concentration which
is in equilibrium in the stationary phase by the concentration which is in equilibrium in the mobile
phase.
Figure 1.2 shows a diagram of how the multi-component gas mixture is led to a column and
separated into its discrete components over time.
F0102.EPS
Multi-component
gas mixture
Sampling
(1st round)
(2nd round)
Detector Concentration signal
A
B
C
(Intake) (Outlet) Column
Injection
Time
Carrier gas
Carrier gas
:Component A, :Component B, :Component C
Figure 1.2 Separating Components Using a Column