Chromatography steric exclusion

This paper concerns the main properties of water soluble pectins in sol and gel states. First of all, the methods of purification and characterization are discussed. The method of steric exclusion chromatography equipped with different detectors is demonstrated as the most useful to determine the macromolecular characteristics of these polymers the role of aggregation is pointed out. 

The best way then to characterize the pectins is the steric exclusion chromatography equipped with a multidetection and particularly a light scattering detector [13]. 

Regnier, F. E. and Noel, R., Glyceropropylsilane bonded phases in the steric exclusion chromatography of biological macromolecules, ]. Chromatogr. Sci., 14, 316, 1976. 

Pozo, C. 1993. Application of steric exclusion chromatography for the separation of degradation products of the solvent used for the reprocessing of the nuclear fuels. Rapport CEA-R-5647. 

The presence of relatively high levels of strong organic chelators like EDTA in the water samples prompted a detailed chemical speciation study aimed at determining whether the organic compounds identified in the survey study are chelated or complexed to radionuclides. Water samples from waste trenches 19S and 27 and inert atmosphere wells WIN and W2NA were fractionated by steric exclusion chromatography and subsequently analyzed for their... 

FIGURE 3. Steric exclusion chromatography of water from waste trenches and inert atmosphere wells at Maxey Flats, sampled July, 1982. Water samples from waste trenches 27 and 19S (440 ml) and wells WIN (585 ml) and W2NA (238.5 ml) were concentrated to 10 ml, pH-adjusted to their original values and chromatographed on a Sephadex G-15 column at flow rates ranging from 28-33 ml/hr. Individual column fractions were collected every 10 min and analyzed for specific organic compounds and radionuclides. 

C. Quivoron, in Steric Exclusion Chromatography of Polymers (J. Janca, ed.), Marcel Dekker, Inc., New York, 1984. 

Gel-type, microporous, resins must swell to expose their catalytically active sites, whereas macroreticular resins have a permanent pore structure (inside these pores, catalytically active sites reside). Pores of the macroreticular resins can be described acceptably in terms of the conventional cylindrical pore model (pore diameter and volume). Pore structure, size, pore volume, and so on have been studied intensively in recent years. Examples of analytical techniques include X-ray microprobe analysis, ESR spectroscopy, NMR, and inverse steric exclusion chromatography (ISEC) the latter yields the best quantitative assessment of the nanomorphology of swollen resins. 

Barth, H.G. (1980). A Practical Approach to Steric Exclusion Chromatography of Water-Soluble Polymers. J. Chromatogr. Sci. 18,409. 

Size exclusion, steric exclusion chromatography, SEC components in a sample are separated according to their molecular size by selective retention on a stationary phase having pores of varying sizes see gel filtration. 

To illustrate the results obtainable in steric exclusion chromatography. Figure 21.24 depicts an HPLC separation of polystyrene standards in a column packed with cross-linked polystyrene particles (average pore size 260 A) of 10-/im d, using tetra-hydrofuran as a mobile phase. Unlike mobile phases in other forms of chromatog-... 

J. Brugnerotto, J. Desbrieres, G. Roberts, M. Rinaudo, Characterization of chitosan by steric exclusion chromatography. Polymer 42 (2001)09921-09927. 

To avoid these artefacts, it was proposed that 0.3 M acetic acid/0.2 M sodium acetate (pH = 4.5) be used as solvent since there was no evidence for aggregation in this mixture [50]. At that time, it was demonstrated that the value of DA modifies the K and a parameters. In this solvent, the absolute M values were obtained from steric exclusion chromatography (SEC) equipped with online viscometer and light-scattering detector, allowing the Mark-Houwink parameters to be determined without fractionation and also the relation between the radius of gyration and the molecular weight. 

Kirkland, and Ely (24) have discussed the SEC technique. Barth (25) has reported a practical approach to steric exclusion chromatography of water-soluble polymers. However, SEC is not easily carried out for the subject polymers because of the high molecular weight (10 -10 g/mole) and the poly-electrolyte characteristics of the charged polymers. In order to obtain meaningful SEC data, the columns, mobile phase, concentration of polymer solution, sample preparation method, flow rate, and shear degradation of the polymer should be considered in an SEC experiment. 

Griineberg, M. Klein, J. Determination and use of cumu-lants of the peak broadening function in steric exclusion chromatography. K- Ooqiod Chromat. 3(10) (1980) 1593 1615... 

For their characterization, alginates must first be purified and isolated under their sodium form. NMR spectroscopy ( H and C) is the most powerful technique to characterize the chemical composition and the microstructure of alginates [46 9]. Purified alginates, isolated under the sodium salt form, were also characterized by steric exclusion chromatography (SEC)with three detectors on line. For commercial products, molecular weights may range between 32 000 and 400 000. A further means of characterization is their intrinsic viscosity using the Mark-Houwink relation ... 

Janca, J. Pokorny, S. Zabransky, J. Bleha, T. On the concentration effects in steric exclusion chromatography under stationary equilibrium conditions. J. Liq. Chromatogr. 1984, 7(9), 1887-1901. 

Bonfils, F. Sainte Beuve, J. Laigneau, J. Koman Achi, A. Alledon, A. Sylla, S. Steric exclusion chromatography study of natural rubber film prepared from fresh field latex. J. Nat. Rubber Res. 1995,10, 143. 

Analysis of the medium aliquots by steric exclusion chromatography (SEC) prior to the introduction of the second macromonomer and after polymerization of the latter showed that the conversion of both macromonomers came close to 100%. The actual molar masses of polymacromonomer were measured by SEC equipped with laser light scattering. As shown in Table 2, a relatively good agreement between expected and targeted values is observed for most of the cases. 

Steric exclusion chromatography (SEC) can be used to determine the molar mass distribution and the average values and Mw can also be determined by viscosimetry using a power law ... 

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