Adsorbents In Gas Chromatography Research Articles

Copper and Nickel Complexes of tert-Butyl Substituted Phthalocyanines as Modifiers for Films Based on Polyvinyl Chloride and Adsorbents for Gas Chromatography

Copper and Nickel Complexes of tert-Butyl Substituted Phthalocyanines as Modifiers for Films Based on Polyvinyl Chloride and Adsorbents for Gas Chromatography

Asphaltenes as Adsorbents in GC. II. Separation of Some Homologous Series and Isomeric Compounds

Four different asphaltenes were separated from Egyptian crudes and employed as gas chromatography (GC) adsorbents. Each asphaltene was used to coat (10% by wt) chromosorb-p having 100–120 mesh size and packed into a 1/4” × 7′ stainless steel column. Asphaltene columns are found to be highly efficient in the separation of some condensed ring compounds, homologous series of alkylated and halogenaled benzenes, some ketones, C3-C5 alcohols, several halogenated alphatics, and cresols. This study reveals that asphaltenes are selective toward the separation of the given condensed ring compounds and have a normal behavior toward the other separations. Asphaltenes can be used as polyfunctional adsorbents for separating different compound classes.

Gas chromatographic analysis of organic compounds on non-polar adsorbents

The applicability of new non-polar adsorbents in gas chromatography has been investigated. Molybdenum and tungsten sulphides are characterized by a lamellar structure, which resembles the structure of graphite, and hence are expected to show chromatographic properties similar to those of graphitized thermal carbon black (GTCB). This assumption was verified chromatographically by comparing the properties of argon plasma-treated thermal carbon black (TCB) with the properties of MoS 2 and WS 2 and MoSe 2. The adsorption characteristics (relative retentions, heats of differential adsorption) were determined at low levels of adsorbent surface coating with reference compounds. The results indicate that the treatment of TCB in a hydrogen-containing plasma (oxygen-free flow) results in lower retentions. The retention of n-alkanes by MoS 2 and WS 2 is higher than that of monoalkylbenzenes with the same number of carbon atoms. Di- n-butyl ether is adsorbed by MoS 2 and WS 2 more weakly than n-nonane, which indicates a homogenous sorbent surface. The adsorption of di- n-butyl ether on MoSe 2 is stronger than that of n-nonane, which indicates an non-homogeneous adsorbent surface. The results made it possible to derive several practically applicable conclusions. MoS 2 and WS 2, for instance, can be used for analytical purposes at lower temperatures than thermal carbon black. The adsorbents under consideration are suitable for the separation of structural and geometrical isomers.

Coordination polymers as stationary phases and adsorbents for gas chromatography : VIII. An attempt to bind poly[chromium(III) diphenylphosphinate] to silica

Coordination polymers as stationary phases and adsorbents for gas chromatography : VIII. An attempt to bind poly[chromium(III) diphenylphosphinate] to silica

Application of molybdenum and tungsten sulphides as adsorbents in gas chromatography

Gas chromatography was used for studying the adsorption of various organic compounds, including halogen-, oxygen-, sulphur- and nitrogen-containing ones, on molybdenum and tungsten sulphides. It is shown that the adsorption on MoS 2 and WS 2 is governed mainly by dispersion forces. Some practical application of these adsorbents in gas chromatography are exemplified.

Effect of surface acidity of activated carbons on their characteristics of adsorption from the vapour phase—comparison of retention time for carbons used as adsorbents for gas chromatography

Seventeen kinds of activated carbons of different surface acidity and of known pore-structure were used as adsorbents for gas chromatography. The retention time of various kinds of substrates was determined for each carbon at different temperatures. It was found that surface acidity of carbons has a marked effect on increasing the retention time for polar substances while showing no effect for non-polar substances. Retention times varied with temperature which suggested, when the effect of surface acidity is taken into account, that the pores which were effective for the Chromatographic adsorption have been determined by the temperature. The heat of adsorption calculated on the basis of the retention times observed at different temperatures showed an inverse correlation with dielectric constant of the adsorbates.

Crosslinked polymethylphenylsiloxanes as adsorbents for gas chromatography

Crosslinked polymethylphenylsiloxanes that are suitable as adsorbents for gas-solid chromatography have been prepared. These new materials are characterized and evaluated as chromatographic supports. Their chromatographic properties are compared to OV-17, a linear polymethylphenylsiloxane, often used as a liquid phase in gas-liquid chromatography. Scanning electron micrographs show that the materials resemble agglomerates of tiny spheres. The materials have surface areas around 5 m 2/g and are thermally stable up to 350°. Small, polar compounds are eluted very early in columns prepared with these adsorbents in a manner similar to macroporous polymers like the Porapaks. Separations of chlorinated benzenes and phenols at temperatures up to 270° are shown.

Chromatographic properties of tuffs containing some zeolites

The separatiing properties of tuffs containing clinoptilolite adn mordenite as adsorbents in gas chromatography were studied, using argon—oxygen—nitrogen—methane—carbon monoxide as a model mixture. It was shown that the treatment of tuffs containing clinoptilolite with hydrochloric acid improves the separation of the oxygen—nitrogen mixture but does not separate oxygen—argon. It was found that natural tuffs containing mordenite have better separation abilities than synthetic sodium mordenite. The enrichment of natural mordenite with calcium or strontium cation improves the separation of oxygen—nitrogen, while the introduction of strontium and barium cations into the zeolite structure improves the separation of argon—oxygen. The temperature of the thermal activation of the specimens greatly influences the separating ability of tuffs containing mordenite.

Synthetic inorganic ion exchangers as adsorbents for gas chromatography

Synthetic inorganic ion exchangers as adsorbents for gas chromatography

Physico-chemical and gas-solid chromatographic evaluation of surface-modified silica gels

Silica gel samples coated with copper(II) tetra-ammonium sulphate, copper(II) bisethylenediamine sulphate and copper(II) bistriethanolamine sulphate were investigated by differential thermal analysis and thermogravimetric analysis. Surface area measurements were made in order to determine the influence of loading on the surface area. Gas-solid chromatographic studies were then carried out in order to evaluate silica gel and surface-modified silica gels as potential adsorbents in gas chromatography. Graphs of retention time against percentage loading of copper were plotted at different temperatures for a large number of gases and vapours. Some possible gas chromatographic separations that can be achieved with the use of surface-modified silica gels as stationary phase are also indicated.

Chlorides of nickel, cobalt and barium as adsorbents in gas chromatography

The adsorptive and chromatographic properties of structurally different chlorides of bivalent metals: NiCl2, CoCl2 and BaCl2, have been studied. Low temperature adsorption isotherms of xenon were used to discover the number and area of different homogeneous crystal faces of the adsorbents. For NiCl2 and CoCl2 which have layer structures with chloride ions situated on one of the crystal face, the contribution of the specific intermolecular interaction energy to the total adsorption energy of aromatic hydrocarbons is far lower than that for BaCl2, all the crystal faces of which contain both chloride and barium ions. The salts studied, either in pure form or coated on the surface of Silochrom have been used to separate compounds which do not differ greatly in their physicochemical properties.

Carbochromes as adsorbents in gas chromatography

1. The optimum conditions of modification of graphitized thermal carbon black with apiezon L and polydimethylsiloxane were determined. 2. Columns with modified carbon black possess high efficiency and selectivity in the selection of organic and organometallic compounds of various structures. 3. The heats of adsorption of organic and organometallic compounds on modified carbon black were measured. The numbers of theoretical plates and coefficients of selectivity of the columns with various samples of carbon black were determined.

Porous polymers as adsorbents in gas chromatography

Porous polymers as adsorbents in gas chromatography

The use of grafted radiation chemical polymerization for the modification of carriers and adsorbents in gas chromatography

1. The method of grafted radiation polymerization was used to modify the surface of solid carriers and adsorbents in gas chromatography. The carriers and adsorbents modified by this method are characterized by a lower surface, lower catalytic activity, and greater efficiency of gas chromatographie separation. 2. The promising nature of the proposed method of modification in gas chromatography was demonstrated for various examples of chromatographic separation.

Polyelectrolyte Reinforced Aerogels of Clays—Application as Chromatographic Adsorbents

AbstractAerogels of clays can be prepared by freeze-drying of clay water gels. The mechanical strength of the aerogels is improved by the addition of water-soluble polyelectrolytes to the hydrogels.The porosity of the powdered aerogels can be adapted to the requirements for adsorbents in gas chromatography by compounding the hydrogels with suitable amounts of polyelectrolytes. Simultaneously, the surface of the clay may be modified by adsorption of polar or cationic organic compounds in order to achieve specific chromatographic separations.Because of the toughness of the clay-polyelectrolyte aerogels, they can be rolled out to thin sheets which may be applied as chromatographic papers.

Complexes of 1,10-Phenanthroline and 2,2´-Bipyridine with Copper(II) as Adsorbents for Gas Chromatography.

Complexes of 1,10-Phenanthroline and 2,2´-Bipyridine with Copper(II) as Adsorbents for Gas Chromatography.

Characterization of Selected Heavy-Metal Salts as Adsorbents for Gas Chromatography.

Characterization of Selected Heavy-Metal Salts as Adsorbents for Gas Chromatography.

New Adsorbents for Gas Chromatography.

New Adsorbents for Gas Chromatography.