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1. Chapter 23 Chromatographic Methods &
2. Capillary Electrophoresis in Medicine
3. 23.1 Ion-Exchange Chromatography 1) Structures
4. Ion-exchange selectivity
R-K+ + Li + ? R-Li+ + K+
selectivity coefficient: 23.1 Ion-Exchange Chromatography
5. b) Hydrated radius :
or Ionic charge?
? bind to ion-exchange resin?
order of selectivity:
23.1 Ion-Exchange Chromatography
6. 23.1 Ion-Exchange Chromatography c) Gradient elution with increasing ionic strength (ionic concentration) to separate one ion from another by ion-exchange chromatography.
7. 3) What is deionized water ?
? [s] is extremely low
important for environmental problem 23.1 Ion-Exchange Chromatography -5
8. 23.1 Ion-Exchange Chromatograph
9. 23.2 Ion Chromatography a high-performance version of ion-exchange chromatography, with a key modification that removes eluent ions before detecting analyte ions.
in semiconductor industry: to monitor anions & cations level at 0.1-ppb levels in deionized water.
in environmental analysis:
10. 23.2 Ion Chromatography (4) Anions are separated by ion exchange &
detected by their electrical conductivity.
It is difficult to detect the conductivity change when analyte
ions are eluted.
Suppressed-ion anion chromatography : Remove the unwanted electrolyte prior to conductivity measurement.
11. 23.2 Ion Chromatography
12. 23.3 Molecular Exclusion Chrom. Molecules are separated according to their “SIZE”.
13. 23.4 Affinity Chromatography Isolate a single compound from a complex mixture.
a. specific binding to s.p.
b. unbind : change pH or change ionic strength
14. 23.5 What is Capillary Electrophoresis? a) Electrophoresis is the migration of ion in an electric field.
15. The greater the charge on the ion, the faster it migrates.
The greater the size of the molecule, the slower it migrates.
Different ions migrate at different speeds, so they separate.
23.5 What is Capillary Electrophoresis?
17. b) Capillary electrophoresis : extremely high resolution in a narrow capillary tube
(only B term in the van Deemter eqn.)
No s.p. ? C = 0
Open tubular column ? A = 0 23.5 What is Capillary Electrophoresis?
21. Hydrodynamic flow induced by a pressure difference, and creates broad band
24. 23.7 Types of capillary electrophoresis
25. 23.7 Types of capillary electrophoresis (1) Capillary zone electrophoresis :
cations > neutrals (unseparated) > anions
(2) Micellar electrokinetic
separate neutral molecules
as well as ions
27. Neutral molecules reach the detector at a time between tmc (the time for micelles to reach detector) and t0 (absence of micelles).
soluble in the micelle ? ? time inside the micelle ? ? migration time ?,
i.e. tr: nonpolar solutes > polar 23.7 Types of capillary electrophoresis
28. (3) Capillary gel electrophoresis
Macromolecules are separated by sieving
Small molecules travel faster than large molecules through the gel. (opposite in molecular exclusion chromatography)
Is used to sequence DNA (opening at p510)
23.7 Types of capillary electrophoresis