Chromatographic analysis of 1,5-diazabicyclo[4.3.0]non-5-enium acetate and its degradation products

The aim of this study was to develop a high-performance liquid chromatographic (HPLC) method using ultraviolet-diode array (UV-DAD) detection for the separation and quantification of a superbase ionic liquid, 1,5-diazabicyclo[4.3.0]non-5-enium acetate ([DBNH][OAc]), and its degradation products. Various types of commercial HPLC columns, including C18 (octadecylsilane), cyano, and mixed mode columns, as well as a sulfobetaine-based zwitterionic hydrophilic interaction liquid chromatography (HILIC) column were evaluated. A rather complex sample mixture containing compounds with both hydrophilic and hydrophobic compounds were also investigated to gain a better understanding of the separation mechanism. The optimal separation of [DBNH][OAc] and its degradation products was obtained using isocratic elution and the HILIC column. With this approach, the linear ranges and limit of detections were determined for the studied compounds. The presented optimal method can easily be adopted to other similar superbase ionic liquids.