Retardation factor:

Various components of a solute travel with different speeds and the distance travelled by each component with respect to that of solvent gives a parameter called 'retardation factor' or R_f.

Even though PC and TLC have many things in common but there are some basic differences in their operation. Here, we shall discuss the basic principles, apparatus required, methodology and some typical applications of both the techniques in the separation of complex mixtures of organic and inorganic compounds.  We shall first describe paper chromatography, its principle, methodology and applications. PC is the simplest of all the chromatographic techniques but it is not so widely used these days. Later, we shall discuss thin layer chromatography, its methodology and applications including modern developments of plate concept and high-performance thin layer chromatography. Note that though PC and TLC remain primarily qualitative techniques but these could also be used for quantitative analysis. A comparative study of the two techniques will also be presented

Objectives

After studying this Unit, you should be able to

• Elaborates the meaning of planar chromatography,
• Define the principle of paper chromatography (PC),
• Provide the meaning of R_f and factors affecting it,
• Define the type of paper used as support and the types of solvent mixtures used in paper chromatography,
• Define how to run and develop the paper chromatogram,
• Elaborates the methodology of separation of inorganic and organic mixtures,
• Provide the potential applications of paper chromatography,
• Define the principle of thin layer chromatography (TLC),
• List the kinds of supports and the types of mobile phases used in TLC,
• Define how to run and develop the thin layer chromatogram,
• Elaborates the advantages of two-dimensional paper and thin layer chromatography,
• Apply plate concept to TLC,
• Define the basic principle of high-performance TLC (HPTLC),
• Elaborates the potential applications of TLC,
• Define the quantitative aspects of PC and TLC; and
• Contras PC and TLC.