Influence on separations

The species of both cation and anion of ILs have also a significanf influence on separation. The increase of the carbon chain length of fhe cationic parf of... 

We found earlier that a theoretical consideration of displacement and transport exerts a unifying influence on separation science, bringing diverse methods under a common descriptive umbrella. The theory leads in a natural way to the formation of categories of separations which can be considered the beginning of a fundamental classificatory system. Here we generalize the results of transport theory to develop a fundamental basis for classification. While the resulting scheme will not be a complete polythetic classification, it will be based upon some of the most fundamental features of the separation process. These basic features, incorporated in the classification, should correlate well with other properties of separations in the same way that the number of outer-shell electrons is directly related to the diverse properties of the elements of the periodic table. This transport-oriented... 

Proteins are mostly separated by CZE. Strong interactions between the analyte molecules and the capillary wall that are predominately electrostatic in nature have a strong influence on separation efficiency. By the use of buffer additives like amines or the use of dynamically or permanently coated capillaries, highly efficient separation of proteins in CZE is achievable. Here, the native proteins with their tertiary structure are separated. Denatured proteins as SDS complexes can be separated in gels. Advantageous are polysaccharide-based polymers, because they permit UV detection at low wavelength (214 nm), impossible with acrylamide-based gels. A separation of SDS-denatured protein standards in a dextran gel is shown in Fig. 7. 

The pore size in the packing does not influence the product throughput nor will it influence substantially the initial cost of a unit of given size. However, because pore size does have a strong influence on separation efficiency, a smaller pore size can be used to obtain good resolution with a smaller unit or with larger throughput. 

This section describes the criteria for the evaluation of stationary phases and their respective influence on separation efficiency and loading. 

The influence of layer thickness on chromatographic and optical properties of HPTLC plates was studied, and for silica gel a reduction from 0.2 to 0.1 mm increased separation speed, had no influence on separation capacity, and increased scanning response by 1.1-1.5 (112). Commercial HPTLC silica gel plates with 3 pm particle diameter and 0.1 mm pm layer thickness were found to have the same or longer separation times and poorer separation performance compared to conventional 5 pm layers of 0.1 or 0.2 mm thickness (113). TLC and HPTLC are compared in Chapter 2 of Ref. 1. 

Liu and Ding (2004) developed a method to separate simultaneously four homologues of alkyltrimethylammonium and four of dialkyldimethylammonium with internal standard (octylammonium) and using indirect UV detection. Decylbenzyldimethyl ammonium chloride was used as chromophore and the influence on separation of buffer concentration, pH and organic solvent (methanol and tetrahydrofuran) was studied. Besides, methanol concentration in a sample solution was tested to avoid the formation of micelles and surfactant adsorption onto the capillary. The method was applied to determine cationic surfactants in five hair conditioners, finding only four homologous (Ci2 ig) trimethylam-monium at a total concentration of between 0.14 and 2.15%. In one of them, analysis with... 

Kaur, S., Barbate, R., Sundarrajan, S., Matsuura, T., Ramakrishna, S., 2011, Hot pressing of electrospun membrane and its influence on separation performance on thin film composite nano filtration membrane. Desalination 279 201-209. 

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