Monolithic columns Dotaz Zobrazit nápovědu
This review article is an updated and extended version of the previous review that has been published 14 years ago . Although history does not change, its interpretation may. Therefore, I took the liberty to revisit the original work and added some of my new thoughts that could be interesting for the generation of scientists who are entering the intriguing arena of monoliths and may want to know the roots of the field. The current monolithic columns that are well applicable for efficient separations, were first described less than 30 years ago, and their advent represented the initial step to their present widespread appearance. At the beginning, the monolithic columns dominated the academic studies. However, several monolithic materials have later been materialized in commercial products. In order to stay within a reasonable size of this contribution, its focus is placed on developments achieved in the previous century. The very early reports are described in more detail since it might be difficult to find the original source.
In this paper, the concentration of N-isopropylacrylamide in the polymerization mixture has been varied to prepare several polymethacrylate monolithic capillary columns. Polymer monoliths combining N-isopropylacrylamide with zwitterion monomer, as well as various dimethacrylate crosslinking monomers have been prepared and characterized. Uracil, thiourea, phenol, toluene, ethylbenzene, propylbenzene, and butylbenzene have been used to characterize retention of prepared capillary columns in the mobile phases with 40-95% of acetonitrile and at working temperatures ranging from 25 to 60°C. By an optimization of six-parameter polynomial models we have found that the retention of small molecules is affected mainly by the concentration of the acetonitrile in the mobile phase with very low contribution of working temperature and combined effect of acetonitrile concentration and temperature. Concentration of the mobile phase controlled also enthalpy of the retention. On the other hand, entropic contribution was almost insensitive to the change of the mobile phase composition, especially for mobile phases containing more than 60% of acetonitrile.
This work describes a comparison of three types of commercial high-performance liquid chromatography silica monolithic columns with different inner diameters and generations of monolithic sorbent: a "classic" monolithic column, the first generation (Onyx™ monolithic C(18), 100 mm × 4.6 mm, Phenomenex); a "narrow" monolithic column for fast separation at lower flow rates (Chromolith® Performance RP-18e, 100 mm × 3 mm, Merck); and a recently introduced "high-resolution" monolithic column, the next generation (Chromolith® HighResolution RP-18e, 100 mm × 4.6 mm, Merck). Separation efficiency (number of theoretical plates, height equivalent to a theoretical plate and van Deemter curves), working pressure, the symmetry factor and resolution were critical aspects of the comparison in the case of the separation of ascorbic acid, paracetamol and caffeine. The separations were performed under isocratic conditions with a mobile phase consisting of 10:90 (v/v) acetonitrile-phosphoric acid (pH 2.80). Detailed comparison of the newest-generation monolithic column (Chromolith® HighResolution) with the previously introduced monolithic sorbents was performed and proved the advantages of the Chromolith® HighResolution column.
- MeSH
- adsorpce MeSH
- kofein chemie izolace a purifikace MeSH
- kyselina askorbová chemie izolace a purifikace MeSH
- paracetamol chemie izolace a purifikace MeSH
- vysokoúčinná kapalinová chromatografie přístrojové vybavení metody MeSH
- Publikační typ
- časopisecké články MeSH
- hodnotící studie MeSH
- práce podpořená grantem MeSH
In this study, we demonstrate the preparation of a macroporous monolithic column containing anchored silver nanoparticles and its use for the elimination of excess radioiodine from the radiolabeled pharmaceutical. The poly(glycidyl methacrylate-co-ethylene dimethacrylate) monolith was first functionalized with cystamine and the free thiol groups liberated by reaction with borohydride. In-house-prepared silver nanoparticles were then attached by interaction with the surface thiols. The deiodization process was demonstrated with the commonly used radiopharmaceutical m-iodobenzylguanidine labeled with radionuclide iodine-125.
- MeSH
- 3-jodobenzylguanidin izolace a purifikace MeSH
- kovové nanočástice chemie MeSH
- methylmetakryláty chemie MeSH
- poréznost MeSH
- povrchové vlastnosti MeSH
- radiofarmaka izolace a purifikace MeSH
- stříbro chemie MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Research Support, U.S. Gov't, Non-P.H.S. MeSH
Monolitická chromatografie je nový přístup k přípravě kolon. Využívá stacionární fáze tvořené jedním kusem materiálu, což umožňuje dosáhnout lepších separačních vlastností. Monolity jsou vyrobeny ze silanů nebo polymerů. V některých oblastech se tento typ kolon již prosadil, díky možnosti snadného uzpůsobení vlastností pro konkrétní potřebu.
Monolithic chromatography is a new way to make chromatographic column. Stacionary phase is made of one block which allows to achieve better separative properties. Monoliths are silica-based or polymer-based. This type of columns have already arrived in some areas because of possibility to adjust them for actual situation.
- Klíčová slova
- polymerové kolony, silanové "rod" kolony,
- MeSH
- biochemie MeSH
- chromatografie * klasifikace MeSH
- lidé MeSH
- polymery MeSH
- silany MeSH
- Check Tag
- lidé MeSH
We prepared 0.53 and 0.32 mm id monolithic microcolumns by in situ copolymerization of a zwitterionic sulfobetaine functional monomer with bisphenol A glycerolate dimethacrylate (BIGDMA) and dioxyethylene dimetacrylate crosslinkers. The columns show a dual retention mechanism (hydrophilic-interaction mode) in acetonitrile-rich mobile phases and RP in highly aqueous mobile phases. The new 0.53 mm id columns provided excellent reproducibility, retention, and separation selectivity for phenolic acids and flavonoids. The new zwitterionic monolithic columns are highly orthogonal, with respect to alkyl silica stationary phases, not only in the hydrophilic-interaction mode but also in the RP mode. The optimized monolithic zwitterionic microcolumn of 0.53 mm id was employed in the first dimension, either in the aqueous normal-phase or in the RP mode, coupled with a short nonpolar core-shell column in the second dimension, for comprehensive 2D LC separations of phenolic and flavonoid compounds. When the 2D setup with the sulfobetaine-BIGDMA column was used for repeated sample analysis, with alternating gradients of decreasing (hydrophilic-interaction mode), and increasing (RP mode) concentration of acetonitrile on the sulfobetaine-BIGDMA column in the first dimension, useful complementary information on the sample could be obtained.
Preparation of organic polymer monolithic columns in fused silica capillaries was aimed at fast gradient separation of proteins. For this purpose, polymerization in situ procedure was optimized, using ethylene dimetacrylate and butyl metacrylate monomers with azobisisobutyronitrile as initiator of the polymerization reaction in presence of non-aqueous porogen solvent mixtures composed of 1-propanol and 1,4-butanediol. The separation of proteins in totally monolithic capillary columns was compared with the chromatography on a new type of "hybrid interparticle monolithic" capillary columns, prepared by in situ polymerization in capillary packed with superficially porous spherical beds, 37-50 microm. The "hybrid" columns showed excellent stability and improved hydrodynamic flow properties with respect to the "totally" monolithic capillary columns. The separation selectivity is similar in the two types of columns. The nature of the superficially porous layer (bare silica or bonded C18 ligands) affects the separation selectivity less significantly than the porosity (density) of the monolithic moiety in the interparticle space, controlled by the composition of the polymerization mixture. The retention behaviour of proteins on all prepared columns is consistent with the reversed-phase gradient elution theory.
The synthesis and characterization of large-bore silica-based monolithic capillary columns (0.32mm×150mm) are presented. Columns were prepared by acidic hydrolysis of a mixture containing tetramethoxysilane (TMOS) and 1,2-bis(trimethoxysilyl)ethane (BTME) in different molar ratios in the presence of polyethylene glycol and urea. The monoliths were modified by zwitterionic monomer [2-(methacryloyloxy)ethyl]-dimethyl-(3-sulfopropyl)-ammonium hydroxide via 3-(trimethoxysilyl)propyl methacrylate. Prepared stationary phases were evaluated by scanning electron microscopy and chromatographic separation of nucleobases and their derivatives in the HILIC mode. The best chromatographic results were obtained with the column prepared from the reaction mixture containing BTME and TMOS in a 1:4 molar ratio. The permeability of such column reached 1.68×10(-14)m(2) and the efficiency, expressed as a height equivalent of the theoretical plate, did not exceed 10.5μm for the tested compounds. The columns were successfully applied to HILIC separation of native and labeled oligosaccharides and glycans released from bovine ribonuclease B and human immunoglobulin G.
- MeSH
- chromatografie kapalinová přístrojové vybavení metody MeSH
- ethan analogy a deriváty chemie MeSH
- hmotnostní spektrometrie s elektrosprejovou ionizací MeSH
- hydrofobní a hydrofilní interakce MeSH
- imunoglobulin G metabolismus MeSH
- lidé MeSH
- methakryláty chemie MeSH
- mikroskopie elektronová rastrovací MeSH
- oligosacharidy analýza izolace a purifikace MeSH
- organické sloučeniny křemíku chemie MeSH
- oxid křemičitý chemie MeSH
- ribonukleasy metabolismus MeSH
- skot MeSH
- trimethylsilylové sloučeniny chemie MeSH
- zvířata MeSH
- Check Tag
- lidé MeSH
- skot MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
Zwitterionic methacrylate based polymeric monolithic columns were prepared in two-step polymerizations, with reduced polymerization times. Characteristic properties such as hydrodynamic permeability, porosity, retention factors, and pore size distribution charts were used for column evaluation. A scaffold column was fabricated by polymerization of poly(lauryl methacrylate-co-tetraethyleneglycol dimethacrylate) and was used without further modification as a support for a poly(N,N-dimethyl-N-methacryloxyethyl-N-(3-sulfopropyl)ammonium betaine-co-bisphenol A glycerolate dimethacrylate) second monolith layer with zwitterionic functionality, for HILIC separations. An additional internal structure was formed by the second monolithic layer. The fabrication procedure was reproducible with RSD<5%. Field emission scanning electron microscopy has also been used to investigate column pore morphology, using a novel technique where the polymeric material is imaged directly, without coverage with a conducting film or particles. The new polar monolithic columns were used for HILIC separations of phenolic acids, flavones, nucleosides, and bases of nucleic acids, with similar efficiencies but different selectivities for zwitterionic methacrylate monolithic columns recently prepared by single step polymerization.
- MeSH
- chemické techniky analytické přístrojové vybavení MeSH
- chromatografie kapalinová přístrojové vybavení MeSH
- hydrofobní a hydrofilní interakce MeSH
- kyseliny polymethakrylové chemie MeSH
- nukleosidy analýza MeSH
- permeabilita MeSH
- polymerizace MeSH
- polymery chemie MeSH
- poréznost MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
