Instant Notes: Analytical Chemistry

gels dissipate Joule heat more efficiently than column gels and have a superior

resolving power.

High-performance capillary electrophoresis(HPCE or CE) is a relatively

recently developed form where solutes are separated in a narrow-bore fused-

quartz capillary tube, 10–75 cm in length and 25–100mm internal diameter (Fig.

2 ). High voltages (10–50 kV DC, or up to 500 V cm-^1 ) result in rapid separations,

and the heat generated is rapidly dissipated through the capillary wall. Solutes

are detected sequentially by a variety of means as they travel towards one end

of the capillary by migration and electro-osmosis(vide infra), but, unlike clas-

sical electrophoresis, only one sample at a time can be analyzed. A comparative

summary of classical and capillary electrophoresis is given in Table 1.

176 Section D – Separation techniques

Sample

Glass plates

Buffer solution

Gel

Buffer solution

Anode

Cathode

(a)

Cathode

Sample

Anode

Buffer solution

Rubber grommet (seal)

Glass or plastic tube

Polyacrylamide gel

Buffer solution

(b)

Fig. 1. Typical formats for classical gel electrophoresis. (a) Slab gel. (b) Tube gel. Reproduced

from M. Melvin, Electrophoresis, 1987 with permission from Wiley-VCH and from M. Melvin.