High-performance liquid chromatography retention mechanisms and their mathematical descriptions

Different mechanisms of analyte behavior in HPLC columns are considered from the point of view of analyte distribution between the adsorbent and the bulk liquid phase. Expressions describing the analyte retention volume are derived for each selected retention mechanism. Methodology of the incorporation of multi-equilibrium processes in the analyte retention expression is suggested for ideal linear chromatography conditions. The description of eluent components’ adsorption is discussed on the basis of the excess adsorption process. The applicability of the excess adsorption description without introduction of the adsorbed layer model or any other convention to the chromatographic process is shown.