Polystyrene-divinylbenzene materials

For organic SEC separations the use of polystyrene/divinylbenzene (PS/ DVB) particles is almost universal throughout the industry. Polymer Laboratories PS/DVB material, PLgel, which is produced in a series of individual pore sizes, formed the basis for the original product line of SEC columns. Developments in the refinement of particle sizing introduced the benefits of smaller particle size and more efficient columns, which significantly reduced SEC analysis time through a reduction in the number of columns required for... 

Gel permeation ehromatography (GPC)/normal-phase HPLC was used by Brown-Thomas et al. (35) to determine fat-soluble vitamins in standard referenee material (SRM) samples of a fortified eoeonut oil (SRM 1563) and a eod liver oil (SRM 1588). The on-line GPC/normal-phase proeedure eliminated the long and laborious extraetion proeedure of isolating vitamins from the oil matrix. In faet, the GPC step permits the elimination of the lipid materials prior to the HPLC analysis. The HPLC eolumns used for the vitamin determinations were a 10 p.m polystyrene/divinylbenzene gel eolumn and a semipreparative aminoeyano eolumn, with hexane, methylene ehloride and methyl tert-butyl ether being employed as solvent. 

Polymer rod carrier material Porous glass Polymer type Polystyrene- divinylbenzene... 

The polarity values of binary acetonitrile/water and methanol/water mobile phases used in RPLC were measured and compared with methylene selectivity (acH2) for both traditional siliceous bonded phases and for a polystyrene-divinylbenzene resin reversed-phase material [82], The variation in methylene selectivity for both was found to correlate best with percent organic solvent in methanol/water mixtures, whereas the polarity value provided the best correlation in acetonitrile/water mixtures. The polymeric resin column was found to provide higher methylene selectivity than the siliceous-bonded phase at all concentrations of organic solvent. 

A pivotal step in the analytical process is sample preparation. Frequently liquid-liquid extractions (LLEs) are used. Solvents, pH, and multiple back extractions are all manipulated to increase selectivity and decrease unwanted contaminants before injection on the GC system. Solid phase extraction (SPE) is more convenient than it used to be because of an increase in commercially available SPE columns. SPE columns are packed with an inert material that binds the drug of interest, allowing impurities to pass through. As with LEE, solvent choices and pH affect retention and recovery. There are three commercially available types of SPE columns, diatomaceous earth (which uses the same principles as LLE), polystyrene-divinylbenzene copolymer, and mixed mode bonded silica (Franke and de Zeeuw, 1998). 

As an alternative, stable high-coverage nonpolar RPC sorbents phases have been prepared by cross-linking hydrophobic polymers at the silica surface, either via free radical 143 or condensation 101 polymerization chemistry. In this case, the underlying silica becomes partly protected from hydrolytic degradation due to the presence of the hydrophobic polymer film coating that effectively shields the support material. Similar procedures have been employed to chemically modify the surface of other support materials, such as porous zirconia, titania, or alumina, to further impart resistance to degradation when alkaline mobile-phase conditions are employed. Porous polystyrene-divinylbenzene sorbents, be-... 

Although the silica-based columns are the most widely used in RP-HPLC separations of peptides, the use of polymeric carriers (polystyrene divinylbenzene) and composite materials (silica particles with a polymeric coating), which are more chemically stable in that they do not break down at pH values higher than 8 as silica does, is gaining currency (54,55). The mobile phase usually consists of a mixture of water and an organic solvent, generally acetonitrile, methanol, or... 

We are interested in the application of polymers as adsorbents, ion exchangers, fuel cells, and permeable materials. In this regard, the first resins with some of these properties were obtained by D Aleleio in 1944 based on the copolymerization of styrene and divinylbenzene. Unfunctionalized polystyrene resins cross-linked with divinylbenzene (Amberlite) are widely applied as adsorbents [191,192], In addition, the polystyrene-divinylbenzene resins functionalized with sulfuric acid (sulfonation) to create negatively charged sulfonic sites are applied as cation exchangers, and treated by chloromethylation followed by animation produce anionic resins [193,194],... 

Several QSRR studies have aimed at comparison of the retention mechanism on individual alkylsilica reversed-phase materials for HPLC employed the LSER-based analyte parameters. It was observed generally that the most important analyte parameters which influenced retention were bulkiness-related parameters (molar volume, molar refraction) and hydrogen-bonding basicity, but not hydrogen-bonding acidity. The analyte dipolarity/polarizability appeared a minor but often significant factor [96,97]. However, on polystyrene-divinylbenzene (PS-DVB) stationary pha.se the dipolarity/polarizability term provided an important positive input to the QSRR [981. 

Non-polar supports like polystyrene/divinylbenzene copolymers or carbon are also used as column materials. Alumina is polar and acidic while TiOi, and zirconia are much more neutral. They all have good aqueous stability compared to silica. Normal phase chromatography is restricted to the separation of stereochemical isomers, diastereomers, low molecular weight aromatic compounds and functionalized long chain aliphatic compounds. 

In addition to the silica-based, reversed-phase particles, polymeric particles are available that utilize a hydrophobic stationary phase, e.g., cross-linked polystyrene divinylbenzene. In these polymeric stationary phases, the backbone of the particle provides the opportunity for hydrophobic interactions. Although these packing materials are available in high-performance particles, the particles cannot withstand the high pressure that silica particles can and thus are typically used in medium- to low-pressure operations. The polymeric stationary phases usually have a series of aromatic... 

Titanium complexes containing polymerizable vinyl-substituted aryloxide ligands have been employed to prepare polystyrene/divinylbenzene-based polymers that incorporate Ti aryloxide fragment into the matrix 446 Such materials have been used to catalyze Diels-Alder reactions with high diastereoselectivity and at rates only three to five times slower than the corresponding homogeneous reactions. ... 

A variety of materials are used as stationary phases for size-exclusion chromatography, including cross-linked dex-tran, polyacrylamide, agarose, polystyrene-divinylbenzene, porous glass, and combinations of the above. Beads of these materials are porous with pore sizes that allow small molecules to be temporarily entrapped. Molecules too large to enter the pores remain entirely in the mobile phase and are rapidly eluted from the column. Molecules that are intermediate in size have access to various fractions of the pore volume and elute between the large and small molecules according to the relation ... 

Polystyrene/divinylbenzene-based ion-exclusion columns are also offered by Hamilton Co. (Reno, NV, USA) under the trade name PRP-X300. This is a 10-pm material with an exchange capacity of 0.2 mequiv/g [4], It is obtained by sulfonation of PRP-1, a macroporous PS/DVB polymer with reversed-phase properties. Fig. 4-2 shows the separation of various organic acids on this stationary phase. Dilute sulfuric acid was used as the eluent. The much higher retention of succinic acid compared to acetic acid reveals that the retention of organic acids is chararcterized, apart from reversed-phase effects, by the formation of hydrogen bonds. 

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