Separation sciences, in all their various forms such as chromatography, field-flow fractionation, and electrophoresis, provide some of the most powerful techniques in analytical chemistry and are applied within a number of important application areas, including archaeology, biotechnology, clinical, environmental, food, medical, petroleum, pharmaceutical, polymer and biopolymer research. Beyond serving analytical purposes, separation techniques are also used for preparative and process-scale applications. The scope and power of separation sciences is significantly extended by combination with spectroscopic detection methods (e.g., laser-based approaches, nuclear-magnetic resonance, Raman, chemiluminescence) and particularly, mass spectrometry, to create hyphenated techniques. In addition to exciting new developments in chromatography, such as ultra high-pressure systems, multidimensional separations, and high-temperature approaches, there have also been great advances in hybrid methods combining chromatography and electro-based separations, especially on the micro- and nanoscale. Integrated biological procedures (e.g., enzymatic, immunological, receptor-based assays) can also be part of the overall analytical process.