Monolithic High‐Performance Liquid Chromatography Columns

Abstract

Monolithic HPLC (high‐performance liquid chromatography) columns have emerged over the recent decades as highly attractive alternatives to conventional HPLC technology. A monolith is considered to be a continuous piece of porous material. Two types of monolithic columns have been developed for liquid chromatography (LC) applications; they are polymer monoliths and silica monoliths, which differ based on their porous properties. Polymer monoliths consist solely of macropores (pores larger than 50 nm), while silica monoliths possess both macropores and mesopores (pores between 2 and 50 nm). Silica monoliths therefore possess higher surface areas than polymer monoliths and have mainly been utilied for the separation of small molecules, where excellent separation performance has been demonstrated. Polymer monoliths on the other hand have been shown to provide excellent separation performance for larger molecules, where the convective transport of these molecules is unhindered by the presence of mesopores. Polymer and silica monoliths can be prepared in a variety of ways, resulting in varied surface chemistries and flow properties, thus allowing their application in a wide range of chromatographic modes, including reversed‐phase (RP), ion‐exchange, hydrophilic interaction, and hydrophobic interaction chromatography (HIC), to name a few. This has allowed for the separation of a variety of analytes, from small molecules such as alkylbenzenes, to larger molecules such as peptides and proteins. They have also found application for the separation of DNA. In recent years, significant attention has been focused on improving and understanding the behavior of these materials and alternative synthetic routes for their preparation.

Development and applications of deep eutectic solvent derived functional materials in chromatographic separation

“…The main issues for using DES as the mobile phase is high viscosity, so careful selection of tubing, temperature, and mobile phase composition as well as the type of DESs and used columns is required. The newly developed HPLC instruments that can withstand high pressure and temperature and the development of highly permeable monolithic columns will hopefully further promote the application of DES in this aspect [66,67]. Another issue is that the strong interaction between DES and the stationary phase may reduce the chromatographic performance of any separation, but this can only be a problem when the same column is used for different mobile phases.…”

Natural deep eutectic solvents as the major mobile phase components in high-performance liquid chromatography—searching for alternatives to organic solvents

“…The difficulty does remain that a number of stationary phases are unable to handle these high temperatures or pressures. Recent developments in the production of highly permeable monolithic columns could solve this issue [49].…”

Emulsion-Templated Macroporous Polymer Micromixers

“…Emulsion-templated macroporous polymers, called polyHIPEs, are particularly interesting for specialty applications, such as scaffolds for tissue engineering, , stationary chromatography phases, , and filters. , PolyHIPEs are synthesized by polymerization of the continuous phase of high or medium internal phase emulsions containing monomer(s). The removal of the aqueous internal phase results in pores .…”