WHOLE COLUMN ABSORBENCY DETECTION IN CAPILLARY ISOELECTRIC-FOCUSING

Isoelectric focusing (IEF) is a very important separation method, especially for protein mixtures. The recent advent of capillary electrophoretic techniques have spawned interest in capillary isoelectric focusing.1-5Typical capillary IEF employs 25-200-μm-i.d. and 12-20-cm-long capillaries with an on-column absorbance detector. Capillary IEF reflects the general advantages of high-performance capillary electrophoresis (HPCE), such as high efficiency, high speed, and small amount of sample. The capillaries are usually modified by the bonding of a polymer, such as polyacrylamide to the wall6to eliminate electroosmotic flow during the focusing process. After focusing, mobilization can be achieved by replacement of a basic catholyte with acid or an acidic anolyte with base,1by the addition of salt to the catholyte or anolyte,2or by hydrodynamic pumping.3Alternatively, Mazzeo and Krull7added methyl cellulose into the ampholyte to create a controllable electroosmotic flow to carry the bands to the detection region. © 1992, American Chemical Society. All rights reserved.