A novel method for characterization and comparison of reversed-phase column selectivity

• A method for characterizing and comparing column selectivity in RPLC was developed.
• LSERs equations at different percentages of organic modifier were obtained.
• LSERs equations at pure water were used to characterize column selectivity.
• Angles and a spider diagram were helpful for selecting proper columns.
• Two columns with best selectivity were used to develop a two dimensional system.

Characterization of reverse-phase column selectivity is helpful for chromatographers to select an optimal column. A novel method, based on linear solvation energy relationships (LSERs) combined with fundamental retention equations, was developed to characterize and compare reversed-phase column selectivity. The retention times of 25 elaborately selected solutes on 12 reversed-phase columns were determined in three linear gradient elutions. Using these retention times, fundamental retention equations were acquired by a complex sample analysis software system (CSASS). When 0%, 10%, 20%, 30%, 40% and 50% acetonitrile were introduced into the fundamental retention equations, the corresponding retention factors were predicted and used to obtain LSER equations by multiple linear regression. In the gradient elution, the retention times of solutes could be accurately determined and the excessively long or short analysis time could be avoided. As the retention factor (ln kw) at a hypothetical 0% organic modifier closely reflected properties of columns, coefficients of LSERs equations obtained based on ln kw were employed to discuss the properties of different stationary phases. An angle and a spider diagram based on solvation energy vectors were used to compare selectivity differences between stationary phases, which provided a visual means for users to select appropriate columns with orthogonal or similar selectivity. These results of column selectivities were compared with those obtained by geometric orthogonality approach, and a consistent result was acquired. Finally, Click TE-CD and XCharge C18PN with highest difference in column selectivity were applied to the separation of Psoralea corylifolia extraction.