Separation of Dihydroergotoxine on Polar-Embedded Reversed-Phase Stationary Phase

The four components of dihydroergotoxine show different pharmacodynamic properties. An analytical method is required to check the compliance of ingredient and dosage forms with their specifications. Traditionally, the baseline separation of dihydroergotoxine can only be achieved with alkaline mobile phases, which damage the silica matrix badly. In this study, a polar-embedded reversed-phase stationary phase-octadecylamide (C18 amide) bonded silica has been prepared and used to separate the four components of dihydroergotoxine with neutral mobile phases. The effects of the mobile phase composition including pH (3.0–8.0), buffer, and organic modifier on the retention behavior of the four components are investigated. A baseline separation of four components has been realized for the first time with a mobile phase, composed of acetonitril-20 mM Na2HPO4 (30:70, v/v, pH 7.0), on a C18 amide bonded silica column. Compared with the traditional methods, the method described here offers several advantages such as improving the separation performance of basic compounds and prolonging the service-time of the HPLC column.