Prediction of the Retention Indices of Benzene and Methylbenzenes Based on their Retention Data-Physico Chemical Properties Relationship

Retention indices of benzene and 12 methylbenzenes were determined on two capillary columns coated with HP-5 and ZB-WAX at 100 °C. Comparison with the retention indices published by other researchers yields a good accordance. The relationship between the retention index values and several physico-chemical properties of these solutes (freezing point, boiling point, molar volume, van der Waals volume, molar refraction, refraction index, connectivity index, dipole moment and vapor pressure) was investigated by multiple linear regression analysis (MLRA). MLRA equations of seven and eight variables predicted retention indices with mean deviations of 0.66–0.97 index-units in squalane and Carbowax 20 M, and 0.76–1.25 index-units in HP-5 and ZB-WAX. PCA was applied to the system of solutes retention data and stationary phases used, giving results consistent with those of MLR analysis. Samples are scattered or joined by curves. An arrangement of the stationary phases according to the polarity is observed. TCEP was one outlier since it is much more polar than any others.Two groups of variables can be envisaged, one of which is close to the origin of the coordinates, the physicochemical properties that depend linearly. Solute vapor pressure and molar volumes were outliers.