Question

can capacity factor be negative

Answer 1

Ideally and experimentally, the capacity factor cannot be negative but theoretically, it can be negative. This is because as we know capacity factor gives us information interaction of a compound with the column's stationery material. It is given by the formula:

(Tr - To) / To, where Tr is the retention time of compound and To is baseline disturbance

The capacity factor will be negative only in one case, i,e, When analyte-analyte interaction is very less and solvent interacts strongly with the stationary material, then solvent gets adsorbed with the surface leaving analyte to elute first. In other words, the analyte will move faster than the solvent in the column. So, experimentally there will always be some analyte interaction with the stationary phase so capacity factor will be positive in there.