Evaluation of column characteristics in RPLC using linear solvation energy relationships (LSERs)

An overview is given of our studies on the use of linear solvation energy relationships (LSERs) for evaluation and comparison of RP‐HPLC columns. From among the columns investigated, 19 columns of different types, viz. 12 narrow‐pore, 7 wide‐pore silicas containing various ligands (C18, C8, C4, CN) and obtained from 7 manufacturers, were compared and evaluated. Retention factors of 32 solutes of widely differing chemical properties were measured and evaluated to determine the effect of stationary phase properties on the retention of various types of solutes. When the same mobile phase is used with the different columns, the regression coefficients determined by multivariate regression characterize the various stationary phases. The columns investigated were evaluated on the basis of the relative importance of the various types of interactions reflecting the various surface properties of the stationary phases. Since the selectivity of separation is more important than is absolute selectivity, we have investigated and compared the various selectivity terms, hydrophobic, polar, and specific selectivity, displayed by the various columns, for the separation of different types of compounds. As the selectivity of separation depends also on the type and composition of the mobile phase, the effect of mobile phase on the various selectivity terms was evaluated.