1. Chromatography Introduction and Plumbing Harris Ch. 23
November 12, 2018

5. Time = tm
“Dead time”

6. Time = tm
“Dead time”
time
No separation!

7. Retention time t’r Mobile phase Stationary phase
Time for solvent molecule is the same as before: tm
Time for analyte molecule is different: tr
Retention time tm
t’r
Adjusted retention time: tr
time

8. If you have many molecules
Retention factor:
Time in stationary phase
Distribution coefficient
Time in mobile phase
If you have many molecules or

9. t’r(1) Selectivity factor Separation factor Relative retention t’r(2)
Mobile phase
Stationary phase
Time for solvent molecule is the same as before: tm
Time for analyte molecules is different: tr(1) and tr(2) tm
t’r(1)
Selectivity factor
Separation factor
Relative retention tr
t’r(2)
time

10. Distribution coefficient
Retention factor k:
Separation factor:

14. Plate Number Plate Height W = 4s L - length of column
Number of theoretical plates:
Plate Number
W = 4s
L - length of column
Height of theoretical plate is:
H = L / N = L  s2 / tr2
Plate Height

15. The van Deemter equation
Zone broadening:
The van Deemter equation
H - plate height
u - flow rate

16. A = 0

18. B

23. van Deemter plot