Chromatofocusing

Investigations of different protein species in complex biological fluids, e.g., cerebrospinal fluid (CSF) and serum, are important tasks in clinical laboratory work as well as in biochemical research. One crucial part of such investigations is the application of a suitable method in order to separate the individual proteins and/or resolve a certain protein into subtypes or microheterogeneous components. There are two major categories of procedures that are used to achieve these separations. One is represented by electromigration techniques, such as electrophoresis or isoelectric focusing, which separate the sample molecules according to size or charge; an immunoelectrophoretic step may also be used, i.e., a separation according to antigenicity. The second major category is formed by the liquid chromatographies, which give a partition of the sample molecules on the basis of size, charge, hydrophobicity, or binding to a biospecific ligand.