Abstract
Isoelectric focusing (IEF) is an excellent tool at analytical scales but has some drawbacks at preparative and process scales. Alternative electrofocusing methods have been around for over a decade but have only recently reached the point where they can begin to compete head-to-head with IEF. This paper describes some of the advances made in this field since the mid-1980s and shows how they are related to IEF by a common mathematical expression. In addition, one new technique is described which allows real-time computer-control of the focusing gradient.