Zone chromatography

Zone chromatography is a variant of the zone melting method, in which the mixture being separated is introduced into a column with a solid solvent and a molten zone is passed repeatedly along the length of the column to separate mixtures into separate bands of their components. Zone chromatography has been used for the separation of mixtures of lanthanides for preparative and analytical purposes The chelates used were mixtures of hydrated / -diketonates and their adducts with 2,2 -bipyridyl (bipy) and acety-lacetonimines. The distribution coefficients of different chelates and binary mixtures have been determined . 

Olech, R.M. Pranis, R.A. Cole, M.J. Janiszewski, J.S. Elutri-Zone Chromatography Applications in a Drug Discovery, in Proceedings of the 50th ASMS Conference on Mass Spectrometry and Allied Topics, Orlando, FL, June, 2002, Abstract No. MPF 205. 

Na2C03 1.5H202 to form amine A-oxide and then Na salt of 4,6-dichloro-2-hydroxy-(l,3,5)-triazine, 89-98% yield. The reactions are carried out in a zoned chromatography column. ... 

Due to the necessity of zone stabilization the separation is carried out in suitable stabilizing media (paper, starch, cellulose, etc.). Interactions with the stabilizing media like adsorption, sieving effects or ion exchange can influence considerably the resulting separation. Zone electrophoresis can be compared to elution zone chromatography. 

Several chapters illustrate how the range of applications of aqueous SEC extends beyond the measurement of MWD of water-soluble polymers. The separation of inorganic salts is discussed in Chapter 4. Chapter 15 describes the analysis of surfactant micelles by SEC. Further explorations of the behavior of associating and aggregating systems appear in Chapter 13 which reviews the Hummel-Dryer method and in Chapter 14 which describes frontal zone chromatography. The chromatographic analysis of pore size distributions by inverse SEC is covered in Chapter 6. The important subject of protein chromatography is dealt with explicitly in Chapters 9-11 as well as in several other sections. 

The chromatogram can finally be used as the series of bands or zones of components or the components can be eluted successively and then detected by various means (e.g. thermal conductivity, flame ionization, electron capture detectors, or the bands can be examined chemically). If the detection is non-destructive, preparative scale chromatography can separate measurable and useful quantities of components. The final detection stage can be coupled to a mass spectrometer (GCMS) and to a computer for final identification. 

The last set of experiments provides examples of the application of capillary electrophoresis. These experiments encompass a variety of different types of samples and include examples of capillary zone electrophoresis and micellar electrokinetic chromatography. 

Biomolecule Separations. Advances in chemical separation techniques such as capillary zone electrophoresis (cze) and sedimentation field flow fractionation (sfff) allow for the isolation of nanogram quantities of amino acids and proteins, as weU as the characterization of large biomolecules (63—68) (see Biopolymers, analytical techniques). The two aforementioned techniques, as weU as chromatography and centrifugation, ate all based upon the differential migration of materials. Trends in the area of separations are toward the manipulation of smaller sample volumes, more rapid purification and analysis of materials, higher resolution of complex mixtures, milder conditions, and higher recovery (69). 

Elution Chromatography The components of the mobile phase supphed to the cohimn ter feed introduction have less affinity for the stationary phase than any of the feed solutes. Under trace conditions, the feed solutes travel through the cohimn as bands or zones at different velocities that depend only on the composition of the mobile phase and the operating temperature and that exit from the cohimn at different times. 

K2C03 CaH2, CaO or sodium, then fractionally distd. Near-dry alcohol can be further dried by refluxing with magnesium activated with iodine, as described for ethanol. Further purification is possible using fractional crystn, zone refining or preparative gas chromatography. 

Cetyl alcohol (1-hexadecanol) [36653-82-4] M 242.5, m 49.3". Crystd from aqueous EtOH or from cyclohexane. Purified by zone refining. Purity checked by gas chromatography. 

Fluoranthene (ben2o[/,A ]fluorene) [206-44-0] M 202.3, m 110-111°. Purified by chromatography of CCI4 solns on alumina, with benzene as eluent. Crystd from EtOH, MeOH or benzene. Purified by zone melting. [Gorman et al. J Am Chem Soc 107 4404 1985.]... 

Crystd from MeOH, or dry diethyl ether and benzene, then fractionally distd under reduced pressure. Purified by column chromatography. Freed from cetyl alcohol by zone melting. 

For these reasons Reaktions-Chromatographie [7] ( Chromatographie fonctio-nelle sur couche mince [1,2]) is steadily gaining in importance. Here the reaction, which also then takes on the role of a clean-up step, is performed at the start or in the concentration zone of the TLC plate. 

The samples were applied to the concentrating zone as bands in the direction of chromatography. The zones were concentrated by brief development in the mobile phase described below almost to the junction between the concentrating zone and the chromatographic layer, followed by drying for 5 min in a stream of warm air. The actual chromatographic separation was then carried out. 

Two-dimensional separations can be represented on a flat bed, by analogy with planar chromatography, with components represented by a series of dots . In fact, zone broadening processes in the two dimensions result in elliptically shaped spots centred on each dot . Overlap of the spots is then possible, but Bertsch (30) also showed how the contributors to the overall resolution, R, along the two axes, and Ry contribute to the final resolution according to the following ... 

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