Chromatography in Microstructures

The possibility to separate a (complex) mixture of chemicals in a sample to gain understanding of the composition of the sample and the amounts of the individual components within the sample, or both, is among the most important and often used analytical techniques. Whenever specific enough sensors are not available or when many components of the sample are of interest, or when these components are contained within a demanding matrix (e.g., proteins in blood), separation techniques are the only available choice to prepare the samples before the next step in the analytical process. Typically, an aliquot of the sample is injected into the separation system, where – if successful – the individual components are separated in time and/or space and, subsequently, monitored, detected, identified, and/or quantified. It is important, in this context, to remember that steps preceding and succeeding the actual separation always also contribute to the overall performance of the systems, which is why they always have to be included in an overall evaluation. Electrophoresis, chromatography, and related variants of these two are among the predominant separation technologies used today.