Principles, types and modes of chromatography

Separation of biomolecules by chromatography relies on different features of the molecule and chromatography system (i.e. stationary and mobile phases). When considering chromatography, two major principles require attention, namely retention and plate theory. 

Retention Simply measures the speed at which a biomolecule moves in a given chromatographic system. 

Retention is measiued as either the retention time (Rt) or retention factor (Rf). Rt is used in high-performance liquid chromatography (HPLC) and gas chromatography, whereas Rf is used in paper and thin-layer chromatography. Rf is calculated using the following formula  

Distance moved by biomolecule along stationary phase 

Distance moved by mobile phase (eluent or solvent front) along the stationary phase 

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To describe and explain the principles, types and modes of chromatography. 

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