Post‐polymerization modification of a new reactive monolith for reversed phase and hydrophilic interaction capillary electrochromatography of neutral, polar, and biologically active compounds

Abstract

A reactive monolith based on the polymerization of 3‐chloro‐2‐hydroxypropyl methacrylate, (HPMA‐Cl), with a crosslinking agent, ethylene glycol dimethacrylate (EDMA), was synthesized and post‐functionalized with a macromolecular ligand polyethyleneimine. Monolithic columns with controlled permeability and pore structure were prepared by free radical polymerization in the presence of a binary porogenic mixture of isopropanol and decanol. The presence of chloropropyl functionality in the pristine monolith allowed the synthesis of a post‐fuctionalized monolith carrying cationic groups that was used to control the magnitude of electroosmotic flow (EOF) in electrochromatographic separation. In the synthesis of pristine monoliths, the feed concentration of functional monomer (ie, HPMA‐Cl) was changed between 30 and 60 v/v % for obtaining cationic monoliths providing satisfactory electrochromatographic separation. The best electrochromatographic performance was obtained with the polyethyleneimine functionalized monolith prepared by using the pristine monolith obtained by 60% (v/v) monomer concentration. This monolith was used in reversed phase and hydrophilic interaction capillary electrochromatography modes for the separation of alkylbenzenes, polycyclic aromatic hydrocarbons, phenols, and nucleosides, using mobile phases with low acetonitrile (ACN) contents ranging between 20% and 35% (v/v). This ACN range was remarkably lower than the content of ACN used on the hydrophilic polymethacrylate‐based monoliths reported previously (ie, >90%). The plate heights up to 5.3 μm were obtained for the separation of nucleosides with the environmental friendly mobile phases whose ACN contents were also remarkably lower than that of similar polymethacrylate‐based monoliths.

Recent developments of monolithic and open‐tubular capillary electrochromatography (2017–2019)

“…The most commonly used preparation method of polymer stationary phase with the desired surface chemistry was carried out via a one‐step molding process of direct in situ copolymerization of the functional monomer, crosslinker, initiator, and in the presence of an appropriate porogen . Concentration and composition of organic monomers are the main factors that affect the characters of monolithic column .…”

Various Strategies in Post-Polymerization Functionalization of Organic Polymer-Based Monoliths Used in Liquid Phase Separation Techniques

“…In another study, the poly(HPMA-Cl-co-EDMA) monolith was subjected to the post-polymerization modification with polyethyleneimine obtaining cationic stationary phase for reversed phase and hydrophilic interaction in CEC [35]. The obtained monolithic column was successfully used for the separation of alkylbenzenes, phenols, PAHs and nucleosides.…”

Organic polymer‐based monolithic capillary columns and their applications in food analysisψ

“…For instance, a hexyl methacrylate capillary monolithic column was used to determine caffeine in food (tea, coffee and cocoa extracts) in a rapid and sensitive manner . Gökaltun and Tuncel synthesized poly(HPMA‐Cl‐co‐EDMA) stationary phases with different HPMA‐Cl feed concentrations and post‐functionalized with a macromolecular PEI ligand . Successful RP separations of PAHs and alkylbenzenes were obtained with the 60% v/v of HPMA‐Cl feed concentration in CEC.…”