Temperature dependence of the retention indices of branched-chain paraffins on non-polar stationary phases

The temperature dependence, ΔI/°C, of the retention indices of manybranches paraffins with six to eight carbon atoms was investigated using SF-96 columns, in the temperature range 80-120°. Linear relationships were observed for all the compounds examined, and the calculation of the correct analysis observed for all the compounds examined, and the calculation of the correct analysis temperature for the separation of interesting pairs of isomers was therefore possible. The dependence of ΔI/°C on the skeletal structure of the compounds permitted the determination of characteristic additive terms correlated with structural groups in the molecules, which could be added to give the overall temperature dependence of the index of any isometric compound. The effect of temperature programming on the separation of interesting pairs of isomers was also investigated.