Standardization of Different Octadecyl Bonded Phases Based on the Retention Equation in Reversed-Phase High-Performance Liquid Chromatography

Abstract

The method for standar dization of different n- octadecyl (C₁₈) bonded phases is discussed based on the retention equation log k'=k_w+cψ in reversed—phase high-performance liquid chromatography (RP -HPLC). The dependence of log k' on eluent composition results in parallel lines for C₁₈ reversed phases. The difference in C₁₈ bonded phases can be compensated for by using hydrophilic index c which is independent of C₁₈ reversed phases for a particular solute. The difference between C₁₈ columns packed with C₁₈ reversed phases arises from the difference in phase ratio. A linear relationship between parameter k_w and the logarithm of the surface coverage of C₁₈ bonded phases has been found. Linear k_w — k_w plots with unit slope on various column pairs have been demonstrated. k_w — k_w plots have been utilized to transfer of retention values from one C₁₈ column to another over a wide range concentration of mobile phase in RP-HPLC.