Comprehensive two-dimensional liquid chromatography-capillary electrophoresis 
systems are summarized in this chapter. A variety of combinations of capillary 
electrophoresis and liquid chromatography modes as well as interfaces and 
detection technologies are discussed. A typical, comprehensive two-dimensional 
system coupled with reverse-phase liquid chromatography with fast capillary 
electrophoresis and hyphenated to mass spectrometry was demonstrated for 
proteomic analysis. A two-dimensional capillary electrophoresis system of 
coupling capillary sieving electrophoresis with micellar electrokinetic 
chromatography and its application in single cell analysis for protein 
expression profiling are presented.