An Insight to Chiral Monolith for Enantioselective Nano and Micro HPLC: Preparation and Applications

Abstract

This review gives an overview of chiral separation principles and their application in enantioselective nano/micro high performance liquid chromatography (n/μ-HPLC) using chiral monolith. In particular, developments in silica and polymer chiral monolithic stationary phases are presented. The preparation and applications of chiral monoliths, the basic chiral separation principles and the mechanisms are discussed.

Enantioselective Nano Liquid Chromatographic Separation of Racemic Pharmaceuticals: A Facile One‐Pot In Situ Preparation of Lipase‐Based Polymer Monoliths in Capillary Format

“…7 Several categories of CSs are available for enantioselective separation of racemates, for example, molecularly imprinted polymers, ligand exchange, cellulose and amylose derivatives, cyclodextrin(s) derivatives, brush-type, macrocyclic antibiotics-based, and protein/glycoprotein-based. 8 Due to their chiral nature and the availability of various functional groups on their surface, proteins can interact with chiral entities by forming not only weak, nonspecific bonds, but also strong and more specific interactions. 9 Despite proteins' ability to discriminate chiral molecules, only a limited numbers of proteins have been investigated as CSs, not to mention binding them on monoliths.…”

An insight into chiral monolithic stationary phases for enantioselective high‐performance liquid chromatography applications

“…The use of particle packed stationary phases with reduced particle size (5 µm or less) is notoriously associated with several drawbacks such as elevated pressure, preparation difficulties, slower flow rates, and the need for end frits. Although some of these limitations can be overcome through the use of UHPLC systems, the price of such systems still represents a significant barrier to the technology . A promising alternative was exemplified through the use of porous monolithic materials .…”

“…A monolith is made up of a single piece of porous solid, which possess a continuous homogenous stationary phase layer (sealed against the walls of the column tube) through which the mobile phase is forced to percolate . Monolith‐based columns represented a promising alternative to particle packed columns for both capillary electromatography (CE) and HPLC analysis due to their increased mass transfer, controlled pore size, ease of preparation, lower back‐pressure, and no requirement of end frits . Additionally, monolithic materials exhibit high hydraulic permeability and supremacy of convection over the diffusion mechanism of mass‐exchange resulting in better separations at extremely high flow rates which in turn shortens the analysis time without a sacrifice on plate numbers .…”

“…The most prominent downside is due to the in situ preparation, characterization, and modification of monoliths. This is in addition to the poor column to column reproducibility of the packing material and, consequently, the inconsistency in separation characteristics . The advantages and disadvantages of monoliths and alternative materials should be always carefully balanced before taking a decision in favor of one material or another.…”

Chiral Monolithic Absorbent Constructed by Optically Active Helical-Substituted Polyacetylene and Graphene Oxide: Preparation and Chiral Absorption Capacity

“…The distinctive characteristics especially porous structure make this unique type of materials remarkably attractive particularly in separation processes . As an important subgroup, chiral monolithic materials also have been attracting wide attention . Chiral monolithic materials fall into two major groups according to the primary framework: inorganic monoliths and organic polymer monoliths.…”