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 C₆₀-immobilized stationary phase. These results demonstrate that solvent deuteration systematically alters intermolecular interactions, as reflected in the chromatographic retention.