Capillary electrochromatography with monolithic silica columns. V. Study of the electrochromatographic behaviors of polar compounds on monolithic silica having surface bound cyano functionalities

Abstract

In this report, a novel polar monolithic capillary column is described for normal phase CEC (NP-CEC) of representative polar compounds including mono- and oligosaccharides, peptides, and basic drugs. The polar monolithic column, which was described in detail in the preceding paper, consisted of silica-based monolith bonded with 1H-imidazole-4,5-dicarbonitrile (IDCN) and is denoted as 2CN-OH-Monolith. Various retention parameters for neutral polar solutes (e.g., mono- and oligosaccharides) and charged polar solutes (e.g., peptides and basic drugs) were evaluated over a wide-range of elution conditions. These retention parameters yielded quantitative assessment for the polar interactions between the model solutes and the stationary phase under investigation as well as the effect of electromigration of charged solutes on their overall migration in NP-CEC. Furthermore, this investigation demonstrated that despite the possibility of achieving isocratic separation in NP-CEC for widely differing polar species, multistep-gradient elution in NP-CEC is preferred to bring about the rapid separation of a large number of polar species in a single run.

CEC with new monolithic stationary phase based on a fluorinated monomer, trifluoroethyl methacrylate

“…The proteins or angiotensin-type peptides were separated in the monolithic stationary phase with n-octyl chains and/or quaternary ammonium groups [20][21][22][23][24]. Silica-based monoliths are one of the important classes of stationary phases commonly utilized in CEC applications [25][26][27][28][29][30]. Cyano-functionalized silica monoliths were successfully used in the separation of various biomolecules such as carbohydrates, nucleosides, nucleic acid bases and other neutral polar species [27][28][29].…”

Monolithic silica capillary columns having immobilized lectins and surface bound polar functionalities for lectin affinity and normal phase nano‐LC and CEC of glycoconjugates, respectively

“…The method for ligand attachment to the surface of the silica monolith is similar to the previously published method [29,30]. A solution containing c-glycidoxypropyltrimethoxysilane in toluene (1:10 v/v) was introduced into the monolith prepared as described in the previous section, which was later put in an oven set at 1108C for 2 h. This procedure was repeated three times.…”

“…The method to fabricate the silica-based monolith is similar to the previously published one [29,30,[47][48][49]. The inner wall of the fused-silica capillary (37 cm6100 lm ID) was treated with a 1.0 M sodium hydroxide solution for 30 min followed by a 0.2 M hydrochloric acid solution for 30 min.…”

“…However, the separation of glycans by normal phase-nano-LC (NP-Nano-LC) and NP-CEC using monolithic column technology has not been fully developed yet [26][27][28] and there still exists ample room for further improvement. This study investigated the separation and retention behaviors of glycans on novel cyano silica-based monolith (referred to as 2CN-OH monolith) which were previously developed [29,30] in our laboratories but not yet exploited and demonstrated in the separation of glycans.…”

Preparation and evaluation of a sulfoalkylbetaine‐based zwitterionic monolithic column for CEC of polar analytes

“…Normally, HI-CEC is run using polar stationary phases in a high-organic and low-aqueous mobile phase to achieve retention of very polar compounds that could not be retained using RP methods [3,6]. Bare silica beads [7,8], ion-exchange particles [9][10][11], silica gel [12,13], silica gel with chemically bonded polar phases [14][15][16], and macroporous polymer-based monoliths [3,4,[17][18][19] are commonly used as polar stationary phases in CEC.…”