Evaluation of Intermolecular Interactions in HPLC Using Deuterated Mobile Phases

Deuterium, a stable isotope of hydrogen, is widely used in analytical and pharmaceutical sciences; however, its influence on intermolecular interactions remains poorly understood. This study aims to clarify the effect of solvent deuteration on solute–solvent and solute–stationary phase interactions by examining retention behavior in high-performance liquid chromatography (HPLC). Deuterated solvents were applied as mobile phases and compared with their hydrogenated counterparts. In reversed-phase HPLC, deuterated solvents increased the retention of all analytes, indicating that the affinity is reduced between deuterated solvents and hydrophobic compounds, likely due to enhanced solvent–solvent interactions. Aromatic analytes particularly increase retention, suggesting that CH−π and OH−π interactions are weakened in deuterated solvents. In contrast, the sensitivity of π-conjugated stationary phases is minimal to solvent deuteration, implying that π–π interactions are less affected. Effects of deuterated solvents were also observed in normal-phase HPLC using a C 60 -immobilized stationary phase. These results demonstrate that solvent deuteration systematically alters intermolecular interactions, as reflected in the chromatographic retention.