In order to understand what HPLC, that is, High Performance Chromatography, it is necessary to understand the meaning of the term chromatography itself.
Chromatography
Chromatography is defined as a procedure by which inert materials and drug principles encountered in pharmaceuticals preparations are separated by fractional extraction, adsorption, or ion exchange on a porous solid.
Chromatography is particularly useful as a means of separating and purifying complex and closely related chemical substance which are difficult to distinguish. Chromatographic techniques are more applicable in those instances where small quantities are involved in the identification test.
Objective
The principle objectives obtainable through the use of any type of chromatography, including HPLC are:
1.Resolution of mixtures into constituent parts.
2.Determination of homogeneity.
3.Comparison of substances suspected of being identical.
4.Purification of any substance or compounds.
5.Quantitative separation from complex mixtures.
6.Indication of molecular structure.
HPLC
Recent developments in liquid chromatography have led to stationary phases that are chemically bonded to solid support .Due to the strength of the covalent bonds between the stationary phase and solid substance, these chemically bonded liquid chromatography columns are quite stable. They are used primarily in column liquid chromatography in which high pressures drive the mobile phase, a form of chromatography called high pressure liquid chromatography or high performance liquid chromatography.
Therefore, HPLC or High Performance liquid chromatography may be defined as the advanced form of liquid chromatography which is characterized by the use of high pressure to push a mobile phase solution through a column of stationary phase allowing separation of complex mixtures with high resolution.
The mobile phase consists of the sample being separated or analyzed as well as the solvent