Single-column chromatography

All models take into account the thermodynamic equilibrium and thereby use the relation between the concentration in the mobile phase and loading of the stationary phase. The simplest model in this classification is the ideal model , which considered the convective transport besides the adsorption equilibrium only. Starting from this model, additional kinetic parameters, e.g. axial dispersion, mass-transfer resistances or adsorption kinetics are taken into account at the medium level. 

The complexity of the models is increasing up to the general rate model at the highest level, which assumes mass-transfer processes with finite velocity at each position of mass transfer. 

In order to describe the physical processes in a chromatographic column mathematically, a mass balance between the mobile and the stationary phase is gener- 

The ideal model (also-called the equilibrium model) developed by Wilson [50] is the simplest form of describing the chromatographic separation process. This model assumes a separation column with an infinite number of plates, where all kinetic effects are neglected. Mobile and stationary phases are permanently in equilibrium state. With the assumptions made, the mass balance for the concentration of each component is given by the following equation  

In this balance the following transport phenomena are taken into account  

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Thus, it is seen that in single-column chromatography, AG (pS) is proportional to the difference in equivalent conductances of the sample and eluent anions ... 

Initial and Boundary Conditions for Single-column Chromatography... 

Main factors influencing separation selectivity in single column chromatography... 

A Method for the Gas Chromatographic Determination of Urinary Testosterone After Prepurification Using Single Column Chromatography... 

As a result, the pyridine ligand is more labile in complex 16 and 17 than in 15 resulting in higher metathesis activity. It must be noted that the presence of the aryloxide ligands increased the affinity of these complexes for silica thus allowing an efficient removal of ruthenium contaminants by a single column chromatography purification. 

Examples of the application of size-exclusion chromatography to the analysis of proteins. The separation in (a) uses a single column that in (b) uses three columns, providing a wider range of size selectivity. (Chromatograms courtesy of Alltech Associates, Inc. Deerfield, IL). 

FIGURE l.l Hydrophobic interaction and reversed-phase chromatography (HIC-RPC). Two-dimensional separation of proteins and alkylbenzenes in consecutive HIC and RPC modes. Column 100 X 8 mm i.d. HIC mobile phase, gradient decreasing from 1.7 to 0 mol/liter ammonium sulfate in 0.02 mol/liter phosphate buffer solution (pH 7) in 15 min. RPC mobile phase, 0.02 mol/liter phosphate buffer solution (pH 7) acetonitrile (65 35 vol/vol) flow rate, I ml/min UV detection 254 nm. Peaks (I) cytochrome c, (2) ribonuclease A, (3) conalbumin, (4) lysozyme, (5) soybean trypsin inhibitor, (6) benzene, (7) toluene, (8) ethylbenzene, (9) propylbenzene, (10) butylbenzene, and (II) amylbenzene. [Reprinted from J. M. J. Frechet (1996). Pore-size specific modification as an approach to a separation media for single-column, two-dimensional HPLC, Am. Lab. 28, 18, p. 31. Copyright 1996 by International Scientific Communications, Inc.. Shelton, CT.]... 

A solution of 1.0 g (33 mmol) of the mixture of heptofuranoside diastereomers (14) in 5 ntL of THE is stirred in an ice-water bath. 3.4 mL of 1 M soln ofTBAF (3.4 mmol) in THF are added, and Ihe reaction is monitored by TLC (CHCI,/CH, OH, 9 1). After ca. 15 min, the reaction mixture is carefully neutralized with dil sulfuric acid, then diluted with water and extracted with CHC13. The extract is dried over Na,S04 and concentrated to give an off-white solid which is a single stereoisomer (by NMR spectroscopy). Column chromatography gives the inositol as a white solid yield 0.61 g (70%) mp 186-187 C (benzene/CH,OH) [a]D + 118 (c = 03, CH, OH). 

Jaglan PS, Gunther FA. 1970. Single column gas liquid chromatography of methyl parathion and metabolites using temperature programming. Bull Environ Contam Toxicol 5 111-114. 

The main toxic pore forming component of P. marmoratus secretion, named pardaxin, was isolated by liquid column chromatography (5). Originally two toxic (5) polypeptides, Pardaxin I and II, were isolated. However, their primary sequences have been found to be identical (6) therefore, the two components most probably represent different aggregates of one polypeptide. This finding is in contrast to the secretion of P. pavonicuSj which contains three toxic polypeptides (8). Pardaxin is a single chain, acidic, amphipathic, hydrophobic polypeptide, composed of 33 amino acids and with a mass around 3500 daltons (5,6). The primary sequence is (6) NHj-Gly-Phe-Phe-Ala-Leu-Ile-Pro-Lys-Ile-Ile-Ser-Ser-Pro-Ile-Phe-Lys-Thr-Leu-Leu-Ser-Ala-Val-Gly-Ser-Ala-Leu-Ser-Ser-Ser-Gly-Gly-Gln-Glu-COOH. 

Hamilton, P. B., Ion exchange chromatography of amino acids. A single column, high resolving, fully automatic procedure, Anal. Chem., 35, 2055, 1963. 

Murren, C., Stelling, D., and Felstead, G., An improved buffer system for use in single-column gradient-elution ion-exchange chromatography of amino acids, /. Chromatogr., 115, 236, 1975. 

Grosjean, D. J., Van Neste, A., and Parmar, S. S., Analysis of atmospheric carboxylic acids using single column ion exclusion chromatography with ultraviolet detection, J. Liq. Chromatogr., 12, 3007, 1989. 

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