Clinical Applications of Capillary Electrophoresis

The term "electrophoresis" was first used by Michaelis in 1909, to - scribe the migration of colloids in an electric field. The first practical elect- phoresis method was described by Tiselius in 1937. He used a U-tube filled with buffer layered on top of sample; migration could be monitored using Schlieren optics. In zone electrophoresis, the U-tube was replaced by paper, a support material employed simply to prevent or minimize diffusion of ions, so that ions applied in a narrow strip to the paper will separate and remain as relatively discrete zones. Paper was superceded by a variety of other media, - cluding cellulose acetate, hydrolyzed starch (starch gel), agarose, and polyacry- mide. The latter, in addition to being a support medium, has size-sieving properties. From the basic zone electrophoresis, other means of separation have been dev- oped. These include, isoelectric focusing, isotachophoresis, density gradient el- trophoresis, and various forms of immunoelectrophoresis. In some ways Capillary Electrophoresis (CE) has gone full circle back to the original method of Tiselius.
In its simplest form, separations occur in a buffer solution within a glass (fused silica) tube and detection occurs as sample moves past an optical window. CE has rapidly developed into a technique that rivals HPLC in its versatility. All the classical electrophoretic separations-zone, IEF, and isotachophoresis-have their counterparts in CE. Excitingly so, and - thoritatively treated in Clinical Applications of Capillary Electrophoresis.