Retention behavior of nucleosides and nucleobases on a 3 μm undecylenic acid-functionalized silica column in per aqueous liquid chromatography and hydrophilic interaction liquid chromatography separation modes

A 3 μm undecylenic acid-functionalized stationary phase (UAS) was prepared for the separation of nucleosides and nucleobases using per aqueous liquid chromatography (PALC) and hydrophilic interaction liquid chromatography (HILIC). The retention behaviors of nucleosides and nucleobases in PALC and HILIC modes were explored by adjusting parameters such as water content, buffer concentration, pH of the mobile phase and column temperature. The experimental data and separation chromatogram demonstrated that PALC could provide retention comparable to that of HILIC for nucleosides and nucleobases. Comparative studies using diluted adenosine solutions evaluated theoretical plates and peak shape for the same retention factors (between 0.25 and 5.0) in PALC and HILIC. There was no buffer component in the mobile phases used to operate the comparisons. HILIC mode is more efficient for adenosine than PALC mode at low retention factors. It's the exact opposite phenomenon for high retention factors. It is proposed that the mass transfer of adenosine between the UAS, the water-rich layer and the ACN-rich mobile phase in HILIC is relatively slow. Given the significant use of toxic ACN in HILIC, PALC emerges as a safer and more effective alternative for separating nucleosides and nucleobases.