London dispersion force

London Dispersion force is a weak interaction that occurs between non polar molecules

There are different types of interactions occurring between the side chains of the beads of the column and the analytes in the sample. One of those interactions is the so called London dispersion force.

This is a weak interaction that occurs between two molecules that are non polar, that is, two lipophilic molecules. This force is present between two instantaneously induced dipoles, which are due to the movement of electrons in the molecules. If the stationary phase has non-polar chains attached to the inert support (for example the C-18 chain seen in the figure), analytes with non polar groups (for example Magnesium Stearate seen in the figure) will present London dispersion forces and stay longer in the column.