D9 – Electrophoresis and electrochromatography: modes, procedures and applications 185
= Surfactant
(negative charge)
= Solute= Electroosmotic flow= Electrophoresis5 101520
Time (min)(^123)
4
5
6
78
9
1011
1 Acetaminophen
2 Caffeine
3 Sulpyrin
4 Naproxen
5 Guaifenesin
6 Impurity
7 Phenacetin
8 Ethenzamide
9 4-isopropylantipyrine
10 Noscapine
11 Chlorpheniramine
mAU
20
mAU
80
60
40
20
0
0
6.0 7.0 8.0 9.0 10 30 50
Time (min) Time (min)
CE HPLC
Hexobarbital (0.1 mg ml–1)
(a)
(b)
(c)
Fig. 2. Micellar electrokinetic capillary chromatography (MEKC). (a) Formation and migration of SDS micelles;
(b) separation of some constituents of cold-relief products; (c) separation of the enantiomers of hexobarbital and
comparison with an HPLC separation on a chiral stationary phase. b and c reproduced from D.N. Heijer, High
Performance Capillary Electroporesis, 1992, with permission from Agilent Technologies UK Ltd and D.N. Heijer.