Question

the column in a gas chromatograph is polar, and a mixture of a polar compound and a non polar compound is injected. which of the two compounds will have the higher retention time? why?

Answer 1

Ans. The polar compound has greater retention time.

The polar molecules may interact with the polar stationary phase (polar column) through H-bonds, dipole-dipole attractions, etc. The greater force of attractions between the polar compound (sample molecules) and the matrix of same polarity retains the molecule for longer time. As a result, the polar molecules in the sample have higher retention time than non-polar molecules.

The non-polar molecules are least attracted by the polar matrix of the chromatography column and eluted first. Thus, non-polar molecules have low retention time in polar column.