Etched succinate‐functionalized silica hydride stationary phase for open‐tubular CEC

Abstract

An open-tubular (OT) CEC column was designed to anchor ionizable succinate-functionalized ligands onto a silica hydride-based stationary phase through surface etching, silanization, and hydrosilation reactions beginning from a bare fused-silica tube. The modified columns that were produced in each step were monitored by analysis of the effect of performance of EOF on the changes of pH values, concentrations, and the amount of ACN added in the running buffers. By tracking the EOF patterns between columns, the author determined that the surface composition of the final product column was a combination of silanols, silica hydrides, and succinate ligands. Furthermore, lower loading volumes of the succinate ligands prepared for the hydrosilation reaction served to complete the mixed-mode OT-CEC columns, and subsequently to carry out the separation of six phenyl alcohols. Studies on the elution order of these alcohols identified the presence of chromatographic interactions in addition to electrophoresis. Based on the employment of a solvation parameter model, these interactions likely included dispersion interactions, dipole-type interactions, and interactions arising through the polarizable electrons in the solute. The optimum buffer conditions for CEC separations of phenyl alcohols, carbonyl-substituted phenols, and a mixture of nucleosides and thymine were a phosphate buffer (50 mM, pH 10.51), a borate buffer (50 mM, pH 8.62), and a borate buffer (50 mM, pH 9.50), respectively. Overall, the hydride-based stationary phases with ionizable ligands were successfully applied to the OT-CEC separations, and these results confidently propose an ideal route to the synthesis of novel OT-CEC columns.

Multi‐walled carbon nanotube composites with polyacrylate prepared for open‐tubular capillary electrochromatography

“…4, which shows EOF at a minimum when ACN content is 40-60%. In fact, the concave shape of the curve could be found in various OT-CEC formats, specifically, in capillaries prepared by direct polymer coating, by stepwise fabrication, or by in situ polymerization [8,28,40,41]. The m eo values determined by using the neutral solute DMSO did not increase with an increasing ratio of ACN in the eluent, acting as if a reversed-phase chromatography solvent was not present at all.…”

“…The effect of various volume ratios of ACN (40,50, and 60%) on electrochromatograms is demonstrated in Fig. 7.…”

The role of methacrylate polymerized as porous‐layered and nanoparticle‐bound phases for open‐tubular capillary electrochromatography: Substitution of a charged monomer for a bulk monomer

“…Furthermore, the g-MAPS molecules fixed on the silanized capillary reacted with the MES monomers and formed a monolayered phase, which held fewer MES ligands in the completed MES-EDMA capillary in comparison with the polymeric phase formed in the BMA-MES capillary. This morphological state was quite similar to a SiH-MES capillary, where a MES monolayer was covalently bonded to the unionizable silica hydride surface (SiH) with only a few free silanols remaining [38].…”

Capillary Electrophoretic Determination of Selected Phenolic Compounds in Humic Substances of Well Waters and Fertilizers

“…The increase in migration time from 70 to 80 mM is more significant than that from 80 to 90 mM. This phenomenon could be contributed to a logarithmic relation between buffer concentration and EOF, 37,38 and a complex relation between buffer concentration and electrophoretic mobility, which could arise from the interaction of solute ion with ionic cloud of counter-ions. 39,40 From these experiments, it was clear that an 80 mM concentration was the best choice.…”