Investigation of neutral monolithic capillary columns with varying n‐alkyl chain lengths in capillary electrochromatography

Abstract

Two different neutral nonpolar monolithic columns series (designated as A and B columns series) each consisting of three columns at varying n-alkyl chain length were prepared by the copolymerization of the functional monomers C8-methacrylate, C12-acrylate, or C16-methacrylate with the cross-linking monomer pentaerythritol triacrylate (PETA) to yield monoliths with surface bound C8, C12, and C16 chains. In the A columns series, the composition of the functional monomers and crosslinker was adjusted to yield comparable chromatographic retention regardless of the alkyl chain length. In the B columns series, the composition of the functional monomers and crosslinker was kept constant yielding chromatographic retention, which increased as expected in the order of increasing the n-alkyl chain length. Due to their direct influences on the monolith porosity and retention energetic, the nature and composition of the monomers at a given porogen composition have largely affected the solute's mass transfer characteristics and sorption kinetics, as assessed by the van Deemter plots and separation efficiencies. The C16-monolith of the A series yielded the highest separation efficiency toward small solutes, but the A columns series were inadequate for protein separation. The C8-monolith of the B series provided the best separation efficiency for proteins while for tryptic peptide mapping, the C16-monolith of the A series seems to provide the best separation. For large protein molecules, the energetically "softer" C8 surface allowed faster sorption kinetics and in turn improved efficiency, while an energetically "harder" C16 surface favored better separation of the smaller size peptide solutes.

Postpolymerization modification of a hydroxy monolith precursor. Part I. Epoxy alkane and octadecyl isocyanate modified poly (hydroxyethyl methacrylate‐co‐pentaerythritol triacrylate) monolithic capillary columns for reversed‐phase capillary electrochromatography

“…The monolith thus obtained facilitated the adsorption of electrolyte ions from the mobile phase thus imparting the monolithic surface with the necessary zeta potential for generating a sufficient EOF . Many other neutral monoliths have emerged since the introduction of neutral PEDAS in 2005 .…”

Photochemical Synthesis and Versatile Functionalization Method of a Robust Porous Poly(ethylene glycol methacrylate-co-allyl methacrylate) Monolith Dedicated to Radiochemical Separation in a Centrifugal Microfluidic Platform

“…Methacrylate polymers are widely used in very different fields such as separation of benzene derivatives [ 20 , 21 , 22 ], peptides [ 21 ], or proteins [ 23 ]. They are also used to separate small molecules [ 24 ] or atoms in hard medium as shown in a previous work [ 15 ]. The combination of their singular porous properties, the various chemistries available and their relatively simple implementation in columns with small internal diameters make them particularly attractive for the new chromatographic challenges of complex matrices analysis [ 25 ] or on-chip separations chromatography [ 26 ].…”

Capillary electrochromatography of proteins and peptides (2006–2015)

“…Various neutral monolithic capillary columns with different n ‐alkyl chain lengths were studied by Puangpila et al. . These columns were prepared by copolymerization of the functional monomers C8‐methacrylate, C12‐acrylate, or C16‐methacrylate with the cross‐linking monomer pentaerythritol triacrylate to yield monoliths with surface bound C8, C12, and C16 chains.…”