Question

Describe why different materials have different elution rates through a stationary phase and list the three main factors that govern how fast a chemical will elute through a column.

Answer 1

>> In chromatography, the separation of different materials depends on the differences in polarity between the eluting compounds and the stationary phase.

>> The polar stationary phase adsorbs more polar compounds. It is retained by more by the stationary phase.

>> The non-polar stationary phase adsorbs more by the non-polar molecules.

>> The selection of the mobile phase is also equally important. The good separation of the molecules is achieved by using fairly polar stationary phase and low polarity mobile phase.

>> Silica gel and alumina are the very good stationary phases. Alumina is a polar adsorbent and is used for the separation of polar compounds. Silica gel is less polar than Alumina. Carbon is the non-polar adsorbent.

Factors affecting the elution of the chemical through the column:

>> The polarity of the mobile phase (solvent)

>> Interaction of the different molecules with the stationary phase

>> Separation of the different materials depends on the particle size of the adsorbent.