US EPA

5343816 

Journal Article 

Elucidation of retention behaviors in reversed-phase liquid chromatography as a function of mobile phase composition 

Tsui, H; Kuo, C; Huang, YC 

2019 

Yes 

Journal of Chromatography A
ISSN: 0021-9673
EISSN: 1873-3778 

Elsevier B.V. 

1595 

127-135 

English 

30837162 

10.1016/j.chroma.2019.02.049 

WOS:000468255700015 

Various retention models have been widely used for understanding the retention mechanisms of solutes in reversed-phase chromatography systems. The models have been used to interpret the often-observed linear plots of the logarithms of retention factor k versus the solvent modifier concentration CM and ln k versus ln⁡CM. In this study, the retention behaviors of nine solutes as a function of acetonitrile (ACN) concentration were systematically investigated using a commercially available C18 column. The thermodynamic properties of solute adsorptions in neat water, determined using van' t Hoff plots, were investigated. Slightly concave upward and downward retention curves were identified for the plots of ln k versus CACN and ln k versus ln CACN, respectively. A three-equilibrium-constant stoichiometric displacement retention model was used to interpret the retention behaviors of the solutes. The model was demonstrated to account for the nonlinearity of the retention curves. The linear fits of the ln k versus ln⁡CACN and ln k versus CACN plots were implied to be more suitably used for high and low ACN concentration ranges, respectively. The model fitted the experimental data satisfactorily over a full range of ACN concentrations; thus, the nonlinearity of ln k versus ln⁡CACN plots was implied to mainly be attributed to the weak ACN-sorbent interactions. U-shaped retention curves were observed for acetone, tetrahydrofuran, tert-butanol, and benzyl alcohol at high ACN concentrations, indicating that the retention behaviors of these solutes may involve two types of interactions, with complementary effects on solute retention factor with increasing ACN concentration. 

Thermodynamic retention model; Chromatography; Reversed phase; van't Hoff plot; Adsorption isotherm