Separation Methods in Analytical Chemistry

This chapter deals with separation methods from the perspective of green analytical chemistry. Gas chromatography, the oldest and most familiar method of separation, is inherently green; however, even this method can be improved by eliminating sample preparation procedures whenever possible. High-performance liquid chromatography (HPLC) employs organic solvents, especially acetonitrile, as eluents. If the laboratory operates many liquid chromatographs, the amount of spent eluent generated is several litres per day – a situation that makes the greening of liquid chromatography pressing. Several possibilities for greening liquid chromatography are described: microscale HPLC, temperature elevation and programming in HPLC, application of green eluent modifiers, supercritical fluid chromatography, and ultra performance liquid chromatography. Capillary electrophoresis (CE) is another liquid-phase separation technique that uses much less eluent, and is therefore an inherently green separation method. The CE method is also a basis for miniaturising separation methods. Miniaturisation is a promising route to greening analytical methods since it significantly reduces energy consumption. It also facilitates the development of portable analytical instruments that can be taken wherever needed, eliminating the time and energy required to transport samples to the laboratory. The emergence of microfluidics as a new paradigm in chemical measurement science is the result of miniaturising analytical instrumentation.