Hydrothermal preparation of hybrid carbon/silica monolithic capillary column for liquid chromatography

A simple, easy and economical approach for the preparation of a hybrid carbon/silica monolithic capillary column was described for the first time by using silica monolith as framework in combination with hydrothermal carbonization at 180°C. During the preparation process, formamide was introduced to the reaction solutions to reduce the dissolution rate of monolithic silica skeleton and its optimal concentration was 1.5 M. Fourier transform infrared spectrometry, scanning electron microscopy, energy dispersive X‐ray spectrometry, and inverse size exclusion chromatography were carried out to characterize the as‐prepared column. The results demonstrated that carbon spheres ranging from 150 to 1000 nm were successfully attached to the surface of silica skeleton. The prepared hybrid carbon/silica column had a permeability of 4.4 × 10^?14 m². Chromatographic performance of the column was evaluated by separation of various compounds including alkylbenzenes, nucleosides and bases, and aromatic acids. The column exhibited an efficiency of 75 000 plates/m for butylbenzene at the optimal linear velocity of 0.23 mm/s. The successful separation of these compounds and the study on mechanism indicated that the column can be applied in mixed‐mode chromatography.