Analysis of Separation Methods:

In analysis, referred above in (i), there may be three aspects:

• Erase of interfering constituents before the actual quantitation of one or more known compounds.
• An Isolation of unknown constituents for subsequent characterization.
• The Analysis of a complex unknown mixture by subjecting the entire sample to separation into individual constituents.

Under "(ii)", for obtaining the pure materials from complex mixtures, the constituent along with the desired purity might be acquired by applying a single process or using a number of separation techniques. In a few cases, in sequence to attain the required level of purity, the separation steps of the similar process may have to be repeated.

The mixtures to be separated vary largely in terms of their complexity. They may contain constituents which differ in their molecular weights, solubility in a solvent, volatility or other properties. The sizes of species may range from atomic dimensions through organic molecules and macromolecules to molecular aggregates.

A large number of separation methods are available that utilize selected characteristics as means of separation. Each of these methods can be further subdivided into different techniques using unique characteristics. In certain cases, the properties of the constituents may be so different that very simple techniques of separation can be applied. An extremely simple example, in this regard, is the recovery of common salt from sea water. Therefore, in other cases, the properties of constituents might be so same that the separation becomes a tedious job. A very well known example of a difficult separation is the separation of Zn (IV) and Hf (IV). The other example in this category is the separation of optical isomers.

Another important parameter which is critical in choosing the separation is the amount of mixture available. In some cases, the amount may be a few molecules. However, in industrial processes it may run in tonnes.