Article

Monolithic silica stationary phases in liquid chromatography.

Department of Chemistry, Jamia Millia Islamia (Central University), New Delhi - 110025, India.
Journal of chromatographic science (Impact Factor: 1.03). 08/2009; 47(6):432-42. DOI: 10.1093/chromsci/47.6.432
Source: PubMed

ABSTRACT During the last few decades, monolithic stationary phases (based on silica and polymers) have been used for fast separations in high-performance liquid chromatography (HPLC) and capillary electro-chromatography (CEC). The present article describes the preparation, properties, and applications of these stationary phases. Attempts have been made to discuss the preparation of reversed-phase monolithic HPLC columns and CEC capillaries. The chromatographic properties of these phases have been described. The applications included their use in HPLC and CEC modalities of liquid chromatography. The optimization of separations of various molecules on these phases has been discussed. Efforts were also made to predict the future perspectives of monolithic stationary phases.

1 Follower
 · 
327 Views
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The integration of natural or biomimetic ligands in membrane processes was explored, focusing on simplicity and originality, withaneyetoincreasingtheoftenmoderateselectivity.Duetotheirsimplestructure,selectionandmanufacturingprocedure, aptamers could dramatically increase the cost effectiveness of ligand-based membrane processes. Proteins are distinctly more complex than aptamers, but many excel in organizing selective transmembrane transport. The channel geometry of aquaporins was also found to be tailored for high fluxes by minimizing vortex formation. Incorporation of bacterial porins could tremendously increase the performance of nanofiltration membranes by increasing the rejection of apolar often more toxic compounds. Sugar-selective porins on the other hand, could be used to manufacture the first chemical-free membrane adsorber. Ultimately, bacterial strains could be selected, through multiple evolution cycles, which express porins tailored to recognize specific molecules. Lectins are definitely better suited than porins for high resolution carbohydrate purification. Lectinscouldbeusedtoeffectivelyseparatedifferentsugarisomersinonebindandelutionstep.ThepotentialofConcanavalin A for the purification of the natural sweetener stevioside was explored. A discrimination factor in dissociation constant of a factor 6 and 23 was obtained insilico relative to glucose and mannose respectively. Finally, a new method was discussed from the field of drug design that can determine the selectivity in silico, independent of other competing ligands or targets. The intrinsicselectivityratioseemstosolveanage-oldproblemandanotherpossibleimpedimenttoswiftindustrialapplicationof ligand-basedmembraneprocesses.
    Journal of Chemical Technology & Biotechnology 03/2014; DOI:10.1002/jctb.4238 · 2.49 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: During the last decade, chiral monolithic stationary phases (CSPs) have been prepared and used for rapid enantioseparations in capillary electrochromatography and HPLC. Various chiral selectors are used to prepare these CSPs. The preparation, properties and applications of these CSPs are discussed in this paper. The attempts have been made to describe optimization strategies and the chiral recognition mechanisms. A comparison of chiral separations in capillary electrochromatography and HPLC is described. Efforts have also been made to predict the future perspectives and challenges of chiral monolithic stationary phases. The most effective chiral selectors include polysaccharides, cyclodextrins and macrocyclic glycopeptide antibiotics. These chiral phases produced acceptable analytical enantiomeric separation of a variety of racemates. However, the development of these CSPs for preparative-scale separations is needed.This article is protected by copyright. All rights reserved
    Journal of Separation Science 05/2014; 37(9-10). DOI:10.1002/jssc.201301326 · 2.59 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Analytical scale silica monoliths are commercially limited to three column selectivities (bare silica, C8 and C18). An in situ modification is reported in detail to overcome this barrier and allow for any functionality of choice to be bonded to the silica surface of the monolithic stationary phase support. The modification method was conducted on a commercial bare silica column to bond the C18 moiety to the silica surface through a silylation reaction. The C18 type of stationary phase was chosen, as this is the most commonly bonded functionality for the majority of stationary phases used for high-performance liquid chromatography (HPLC) separations. The C18-modified monolith’s performance was compared to a commercial C18 monolithic and a particle packed column of the same analytical scale column dimensions (100 × 4.6 mm). The modified C18 monolith proved to be of high quality with an efficiency of 73,267 N m−1, fast analysis times (operated at flow rates up to 3 mL min−1 using a conventional 400 bar HPLC system) and improved resolution of a set of polar and non-polar substituted aromatics in comparison to a commercial C18 monolith.
    Chromatographia 03/2014; 77(9-10). DOI:10.1007/s10337-014-2667-z · 1.37 Impact Factor

Full-text (4 Sources)

Download
1,492 Downloads
Available from
May 29, 2014