Ion-exchange layer

Mobile phase Partition Thin layer Ion exchange Electrophoresis... 

Preliminaries. In this chapter we shall address the simplest nonequilibrium situation—one-dimensional locally electro-neutral electrodiffusion of ions in the absence of an electric current. We shall deal with macroscopic objects, such as solution layers, ion-exchangers, ion-exchange membranes with a minimum linear size of the order of tens of microns. 

Cook EB, Dennis M, Ochillo RF (1981) Application of thin layer, ion exchange, and high performance liquid chromatography to separate pharmacologically active components of an African arrow poison of plant origin. J Chromatogr 4 549-557... 

Cantwell and co-workers submitted the second genuine electrostatic model the theory is reviewed in Reference 29 and described as a surface adsorption, diffuse layer ion exchange double layer model. The description of the electrical double layer adopted the Stem-Gouy-Chapman (SGC) version of the theory [30]. The role of the diffuse part of the double layer in enhancing retention was emphasized by assigning a stoichiometric constant for the exchange of the solute ion between the bulk of the mobile phase and the diffuse layer. However, the impact of the diffuse layer on organic ion retention was danonstrated to be residual [19],... 

Cantwell and co-workers proposed a surface adsorption, diffuse-layer ion-exchange double-layer model in which they underlined the role of the diffuse part of the double layer by assigning a stoichiometric constant for the exchange of ions. 

Bases, nucleosides, nucleotides (continued) Thin layer ion exchange chromatography Tomasz [105]... 

The most common amino polysaccharide is chitosan, derived from chitin by N-deacetylation, and the N-deacetylation reaction can be conducted with little degradation of the polysaccharide chain. The depolymerization and sulfation of chitosan by sulfuric acid have been studied. Chitosan has several applications, for example, in the collection and separation of metal ions, and, in admixture with cellulose, for thin-layer, ion-exchange chromatography. - ... 

The direct insertion of coordination compounds the layered ion-exchangers... 

The X-ray photoelectron spectroscopy (XPS), with its information on the density of the electronic charge of the various elements present in the first 20-30 A of a solid surface, has been very helpful in determining the interactions occurring between the "in-situ" formed complexes and the layered ion-exchangers. 

Intercalation of polyoxocations in the layered ion-exchangers has recently been studied. 

The direct insertion of coordination compounds the layered ion-exchangers is also possible ([Cu(phen " ] easily accommodates, at room temperature, between the layers of the pre-swelled a-ZP (9)) but generally forcing operative conditions are required (26,27). Another way of forming complex species between the layers of a-ZP has been tested very recently (28) a partially Co -exchanged a-ZP was contacted with vapors of dicyanobenzene at 200 and, in analogy with what occurs in some zeolites, formation of some Co(II)-phthalocyanines in a-ZP has been observed. 

These theories are based on the interaction of the solute ion with the charged surface layer established by the adsorbed counterion and by adsorbed competing ions. The nonstochiometric models apply the Poisson-Boltzmann equation to estimate retention from an electrostatic point of view. The electrical double-layer model applied uses different approaches such as liquid partition , surface adsorption, diffuse layer ion-exchange , and sru face adsorption doublelayer models. It is not possible to draw conclusions about the ion pair process from chromatographic retention data, but each model and theory may find use in describing experimental results under the particular conditions studied. 

THIN LAYER ION EXCHANGE CHROMATOGRAPHY (TLC) PAPER IRON EXCHANGE CHROMATOGRAPHY GEL PERMEATION CHROMATOGRAPHY (GPC)... 

Depending on its nature, the layer promotes the separation of molecules by (1) physical sorption of solutes from solution onto the surface-active groups of the layer particles (adsorption) (Scott and Kucera, 1979), (2) dissolving of solutes into a stationary liquid held on the layer (partition), (3) attraction of ions to sites of opposite charge on the layer (ion exchange), or (4) retention or rejection of solutes on the basis of molecular size and/or shape (size-exclusion or gel-permeation TLC). The boundary between adsorption and partition is quite obscure because both can involve the same types of physical forces, that is, permanent and... 

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