Chromatographic and spectroscopic methods are widely used today for analytical purposes. Chromatographic techniques are applied not only for off-line analysis, but also for the on-line determination of minute amounts, as well as large-scale preparative separations. In fact, not only monomers, but also polymers and oligomers can be separated by chro­matography, although in the former case it is essentially a group separa­tion. There are several forms of chromatography using different mobile and stationary phases, with the two main forms of instrumental chroma­tography being liquid (LC) and gas chromatography (GC). According to IUPAC definition, chromatography is a physical method of separation in which the components to be separated are distributed between two phases, one of which is stationary, while the other (mobile) moves in a definite direction.