Separation of nucleosides and their bases by reversed-phase liquid chromatography using pure water as the mobile phase

A new reversed-phase liquid Chromatographic (RP-LC) method for the separation of nucleosides and their bases using pure water as the mobile phase is described. A conventional octadecylsilica (ODS) stationary phase was used and modified with strong-positively/strong-negatively charged zwitterionic surfactants. When ODS is modified in this manner, hydrophobic interactions between the stationary phase (ODS) and the analytes (nucleosides and their bases) are reduced dramatically. Subsequently, if pure water is used for the mobile phase then an ‘effective’ distribution of the analytes between the stationary phase and the mobile phase can be achieved. It is proposed that the ODS is subjected to electrostatic fields produced by the positive and the negative charges in the strong zwitterionic surfactant. Furthermore, the hydrophobic interactions between the ODS and the analytes are greatly reduced by the electrostatic interactions emanating from these electrostatic fields. The practical applications of this and the possible mechanisms involved are described and discussed in this paper.