t ime
isothermal
(low temperature)
A
B
C
D
t ime
isothermal
(high temperature)
A
B
C
D
t ime
temperature
program
ramped
temperature
A
B
C D
Fig. 4.5 Influence of ramped temperature during analysis on the gas chromatographic separation
(adopted from and simplified after Schwedt 2007)
Van-Deemter equaƟon
+ +
u min
H
B-Term
Term A
Term C
10
20
30
40
50
60
70
80
90
mean linear gas velocity (u)
N 2
He
H 2
best separaƟon performance
H
Fig. 4.6 The role of carrier gas velocity on separation efficiency in gas chromatography as
described by the Van-Deemter relation
44
4 Instrumental Analysis
isothermal
(low temperature)
A
B
C
D
t ime
isothermal
(high temperature)
A
B
C
D
t ime
temperature
program
ramped
temperature
A
B
C D
Fig. 4.5 Influence of ramped temperature during analysis on the gas chromatographic separation
(adopted from and simplified after Schwedt 2007)
Van-Deemter equaƟon
+ +
u min
H
B-Term
Term A
Term C
10
20
30
40
50
60
70
80
90
mean linear gas velocity (u)
N 2
He
H 2
best separaƟon performance
H
Fig. 4.6 The role of carrier gas velocity on separation efficiency in gas chromatography as
described by the Van-Deemter relation
44
4 Instrumental Analysis