Polymer coated packings

Hanson, M., Kurganov, A., Unger, K. K., and Davankov, V. A., Polymer-coated reversed-phase packings in high-performance liquid chromatography, /. Chromatogr. A, 656, 369, 1993. 

Kutsuna, H., Ohtsu, Y., and Yamaguchi, M., Synthesis and characterization of highly stable polymer-coated aminosilica packing material for high-performance liquid chromatography, ]. Chromatogr., 635, 187, 1993. 

Besides the above differentiation, restricted-access media can be further subdivided on the basis of the topochemistry of the bonded phase. Packings with a uniform surface topochemistry show a homogenous ligand coverage, whereas packings with a dual topochemistry show a different chemical modification of the pore internal surface and the particle external surface (114). Restricted-access media of the former type are divided into mixed-mode and mixed-function phases, bonded-micellar phases, biomatrix, binary-layered phases, shielded hydrophobic phases, and polymer-coated mixed-function phases. Restricted-access media of the latter type include the Pinkerton s internal surface reversed-phase, Haginaka s internal surface reversed-phase diol, alkyl-diol silica, Kimata s restricted-access media, dual-zone phase, tris-modified Styrosorb, Svec s restricted-access media, diphil sorbents, Ultrabiosep phases. Bio Trap phases, and semipermeable surface phases. 

The technique was further improved by employing a polymer coating on the polymeric fibers packed in a fused silica capillary. The coating material was based on GC stationary phases. The polymer-coated fiber-packed capillary was used as the sample loop of the LC injection valve for the extraction of phthalate esters from river water and wastewater.22 The coated-fiber extraction capillaries demonstrated a better extraction efficiency and lower limit of quantification (LOQ) than the uncoated-fiber capillaries. Also, the coated fibers were similarly packed in a PEEK tube, which was used as the injection loop or integrated in the rotor of an LC injection valve employed for the extraction of phthalates. The results clearly showed that an extraction with high selectivity could be established with an appropriate type of polymer coating.23... 

Octadecylsilane (ODS) This is a polymer-coated silica packing with increased loadability of a porous silica support. Nonpolar compounds may be separated using the hydrophobic functionalities offered on ODS. 

Silica-base stationary phases have also been employed for enantiomeric separations in CEC [6,72-81]. In the initial work on chiral CEC, commercially available HPLC materials were utilized, including cyclodextrins [6,74,81] and protein-type selectors [73,75,80] such as human serum albumin [75] and ai-acid glycoprotein [73]. Fig. 4.9, for example, depicts the structure of a cyclodextrin-base stationary phase used in CEC and the separation of mephobarbital enantiomers by capillary LC and CEC in a capillary column packed with such a phase. The column operated in the CEC mode affords higher separation efficiency than in the capillary LC mode. Other enantiomeric selectors are also use in CEC, including the silica-linked or silica-coated macrocyclic antibiotics vancomycin [82,83] and teicoplanin [84], cyclodextrin-base polymer coated silicas [72,78], and weak anion-exchage type chiral phases [85]. Relatively high separation efficiency and excellent resolution for a variety of compounds have also been achieved using columns packed with naproxen-derived and Whelk-0 chiral stationary phases linked to 3 pm silica particles [79]. Fig. 4.10 shows the... 

Inverse gas chromatography (IGC) refers to the characterization of the chromatographic stationary phase (polymer) using a known amount of mobile phase (solvent). The stationary phase is prepared by coating an inert support with polymer and packing the coated particles into a conventional gas chromatography column. The activity coefficient of a given solvent can be related to its retention time on the column. The equipment itself is commercially available, easily automated, and extremely versatile. 

The commercial availability of zirconia-based HPLC packings are mainly related to the enormous extensive research of P. Carr and other workers [37, 38]. They applied zirconia as the starting material for a number of different polymer-coated RP phases. 

The development of modem capillary columns has led to improved resolution and has also simplified the process of running gcs considerably. The columns are normally made from fused silica capillary with an inside diameter of between 0.2 and 0.5mm, and are polymer coated. They have no packing, but instead the liquid stationary phase is bonded to the inside wall of the capillary, and this allows gas to flow very easily. Because of this the columns can be made much longer than packed columns (between 12 and 100m) and they are typically ten times as efficient. Capillary columns give extremely high sensitivity and only a very small quantity of material is required. For this reason the injector normally incorporates a splitter, so that only a small portion of the sample injected actually enters the column. 

Polymeric flat sheet membranes are easy to prepare, handle, and mount. For gas separation, the flat sheet membranes are composites with a selective polymer coated on a support. A commercial configuration that has been quite successful for hydrocarbon vapor recovery is the Borsig envelope type module (see Figure 4.19) [107]. Packing densities for flat sheet membranes may be in the range of 100 00 m /m [1]. 

Mao, Y. Fung, B.M. Use of alumina with anchored polymer coating as packing material for reversed-phase high performance liquid chromatography. J. Chromatogr., A 1997, 790, 9-15. 

In order to avoid the contribution of the residual silanols to solute retention, many packing materials that should not have silanols have been developed [4]. They are polymer-based materials and also polymer-coated silica phases. These polymer-based or polymer-coated phases can be recommended as very useful and stable stationary phases in LC separations of polar compounds they also offer much better stability for use at higher pH alkaline conditions. 

Packed column SFC stationary phases are very similar or identical to those used for HPLC. With neat CO2 mobile phases, polymer or polymer-coated silica stationary phases have typically been used. With modified-C02 mobile phases, bonded-phase silica columns are typically used. For structural separations, diol, amino, or cyano stationary phases are most often used. For stereochemical separations, derivatized polysaccharide-bonded silica columns are most often the stationary phases of choice. A powerful feature of modified-C02 pSFC is the ability to serially connect different stationary phases to obtain enhanced or mul-... 

Inverse gas chromatography has proven to be a particularly important technique for the investigation of polymers, with most studies making use of packed columns. IGC also has been recently extended to the investigation of fibers and of polymers coated on capillary columns. The preparation of each of these columns is very important to overall success. 

Reversed phase packings Non-polar Reversed phase silicas with n-alkylsilyl groups, reversed phase silicas with hydro-phobic polymer coatings, hydrophobic cross-linked organic polymers, porous carbon Aqueous/organic mobile phases... 

Reversed Phase Packings with Polymer Coatings (Types of Polymer Coatings)... 

Other authors have used coated columns successfully for ion chromatography. Polymer-based packing or a C18 silica packing coated with methyl green or ethyl violet [4] has been used to coat substrates for the separation of anions. Several dyes httvc been used to coat substrates for separation of various metal ions [5]. 

Additionally liquid-liquid (partition) HPLC can be performed with packings which are polymer-coated materials such as those illustrated in Table 10.5. 

Kanda, T. Kutsuna, H. Ohtsu, Y. Yamaguchi, M. Synthesis of polymer-coated mixed-functional packing materials for direct analysis of drug-containing serum and plasma by high-performance liquid chromatography. J.Chromatogr.A, 1994, 672, 51-57 [serum plasma direct injection column temp 40 also carbamazepine, chloramphenicol, indomethacin, phenobarbital, phenytoin, theophylline]... 

Surface silylation of solid supports, glass columns, inserts, or even glass-wool spacers and glassware for the sake of surface deactivation remains highly recommended in biochemical GC. An alternative approach to surface deactivation is the method of Aue et al. [93], in which thermal treatment of polymer-coated supports results in a partial linkage of the macromolecule to the surface. This approach has been successfully employed with both packed and capillary columns. 

Columns packed with small polymer-coated glass beads, because of their large surface area to void volume ratio, provide a severe test of platelet-surface compatibility. A 2.5 ml column packed with 0.35 - 0.50 mm diameter beads provides -200 cm of surface area which, at a point in time, is exposed to -0.6 ml of blood. This is equivalent to spreading a film of blood 30 urn thick on a flat surface and, assuming a mean capillary diameter of 7 urn, represents approximately one-twentieth the surface to volume ratio of a capillary bed. 

Corrosion inhibitors are substances whose introduction in small amounts into a corrosion system (aggressive medium, polymer coating, lubricating or packing material, etc.) produces noticeable corrosion abatement in metals. Cl are subdivided into adsorption and passivating Cl by their action mechanism. The former protect metals by affecting the kinetics of the electrode corrosion processes. The latter promote the formation of an oxide or other films on a metal product to transfer the metal into the passive state. 

The metallic rectangular test specimens in the form of flat sheets or manufactured articles or their parts protected in a certain manner by temporary anticorrosion methods (e.g. by application of some inhibited polymer coating or packing in an inhibited film) are placed in the open air or under shelters for outdoor testing. 

Silica coated with a crosslinked polyimine serves the same purpose. Yet packings based on an organic polymer are hydrolytically more stable. An example is Asahipak NHj, which is a polyamine-derivatized polyvinylalcohol-based packing. Since there is no concern about any dissolution of the polymer, this packing is currently probably the best choice ot carbohydrate separations via HILIC. 

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