Advanced Techniques of Separation and Purification

The various types of Chromatographic Separation have been developed partly to avoid the above disadvantages, but (more particularly) to provide methods of separation on a micro-scale. Three methods are described below  

Paper chromatography in particular frequently enables the components of a mixture to be separated and identified when only 1-2 mg. of the mixture are available, the process being independent of the relative solubilities of the components. 

A mixture can often be separated into its components by utilising their selective adsorption from solution by a suitable substance, such as active alumina the separation can be readily followed if the components are coloured. 

If the components are colourless, their separation can often be followed by working in a quartz (or special glass) tube which is placed in the light of a mercury lamp. The separate zones are then often revealed by their fluorescence. 

The process of chromatographic separation is illustrated in the following experiment, in which a wider tube than usual is employed to give a reasonably rapid separation within the time normally available to students. The alumina employed is the usual active alumina as supplied by dealers. 

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