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modern advances in chromatography - springer

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[...]... Removing the in- line end-frit and flushing out the extra-column packing materials using reversed flow direction 5 Sintering of the packing materials to create the inlet end-frit at a distance representing the desired packed segment length followed by the removal of the polyimide coating from the detection window close to the outlet frit 6 Cutting off the excess capillary close to the inlet frit 7 Washing... These include: 1 Attaching an in- line end-frit and packing the column by pumping a slurry of beads and solvent into the capillary under high pressure Sonication is recommended to achieve better quality 2 Flushing the packed column with water at high pressure to replace the solvent 3 Preparing the outlet end-frit at the desired distance from the column end by sintering the silica beads using heating to... tripeptides (Gly-Gly-Phe and Phe-Gly-Gly) was also observed in a pH 7 buffer using this type of functionalized poly(styrene-co-divinylbenzene) monolithic column However, the addition of acetonitrile to the mobile phase significantly decreases the mobility of the analytes thus making this approach less attractive [132] Zhang developed a monolithic poly(styrene-co-divinylbenzene) CEC column in which the... mmol/l a-alanine and 60 mmol/l lactic acid pH 3.7, detection at 211 nm, pressurized injection for 2 s using vacuum drosilylation reaction The bonded phase was characterized using a number of analytical methods such as diffuse reflectance infrared Fourier transform (DRIFT), solid-state cross-polarization magic-angle spinning (CP-MAS) NMR, photoelectron spectroscopy (ESCA) and optical methods such as UV-visible... capillary is filled with an aqueous polymerization mixture that contains monovinyl and divinyl (crosslinking) acrylamide-based monomers as well as a redox free radical initiating system, such as ammonium peroxodisulfate and tetramethylethylenediamine (TEMED) Since initiation of the polymerization process begins immediately upon mixing all of the components at room temperature, the reaction mixture must... consisting of 5-mm, 9 0- and 3-mm, 150 0- ODS beads, respectively [49] All these methods are solving the problem of column stability since the fused beads cannot move However, these approaches often do not avoid the in situ fabrication of frits, one of the critical operations in the preparation of CEC columns 4.5.2 In Situ Prepared Monoliths In contrast to the above technologies that involve packing beads,... surface forming a sub-layer covered with a top layer of C18 alkyl chains [59, 60] These materials afford much higher electroosmotic flow than their non-sulfonated counterparts and exhibit an interesting selectivity in the separation of nucleosides and other families of compounds The majority of CEC-studies in the early 1990s have been carried out with columns packed with the then state-of-the-art 5-mm octadecyl... by Wulff in the 1970s have been detailed in several excellent review articles [122–124] Imprinted monoliths have also received attention as stationary phases for capillary electrochromatography The imprinting process shown schematically in Fig 21 involves the preorganization of functional monomer molecules such as methacrylic acid and 30 F Svec Fig 21 Molecular imprinting of (R)-propranolol using methacrylic... the crosslinking monomer (Reprinted with permission from [126] Copyright 1998 Elsevier) The enantioselectivity of a given polymer is predetermined by the configuration of the ligand, R-propranolol present during its preparation Since the imprinted enantiomer possesses a higher affinity for the polymer, the separation is obtained with a predictable elution order of the enantiomers vinylpyridine around... imprinted monolithic capillaries in 1997 [125–127] Isooctane was used as a porogen in order to produce a macroporous structure with large pores without interfering with the imprinting process These imprinted monoliths were Capillary Electrochromatography: a Rapidly Emerging Separation Method 31 successfully used for the separation of the enantiomers of propanolol, metoprolol, and ropivacaine Using . Engin/Biotechnol 76: 233–255 Article in PDF format Online publication: May 14, 2002 SpringerLink Helpdesk © Springer- Verlag Berlin Heidelberg 2002 Página 2 de 2 SpringerLink: Advances in. using heating to a temperature of over 550 °C. 4. Removing the in- line end-frit and flushing out the extra-column packing ma- terials using reversed flow direction. 5. Sintering of the packing materials. y0 w0 h1" alt="" Advances in Biochemical Engineering/Biotechnology ISSN: 072 4-6 145 (printed version) ISSN: 161 6-8 542 (electronic version) Modern Advances in Chromatography Volume Editor:

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