Size exclusion chromatograph separation

Brown, R. S., Hausler, D. W., Taylor, L. T., and Carter, R. C., Fourier transform infrared spectrometric detection in size-exclusion chromatographic separation of polar synfuel material, Anal. Chem., 53, 197, 1981. 

Although the mechanism of SEC separation is controlled by linear molecular size as well as other parameters, the separation pattern is very reproducible. Considering all the molecular parameters responsible for the size exclusion chromatographic separation pattern and the known separation patterns of a number of compounds, it is possible to predict the retention volume of a compound of known strucure. Based on the same principle the retention volume gives information on the structure of the molecule. 

High-Performance Size-Exclusion Chromatographic Separations... 

Columns used for size-exclusion chromatographic separations of macromolecules with different molecular masses are generally longer (25-100 cm) and broader (6-10 mm) than conventional analytical columns. Semi-preparative and preparative columns have internal diameters from 0.6 to 5 cm and even larger columns are used for industrial pilot-plant and process separations (see Chapter 6). 

What is the size-exclusion chromatographic separation sequence for the sugars shown in Figure 12.5 (ion-exchange chromatogram) ... 

What is the size-exclusion chromatographic separation sequence for the sugars... 

Figure 5. Size exclusion chromatographic separation of hemicelluloses in the aqueous extract after steaming birchwood at J90°Cfor 10 min. The original extract has been ultrafiltrated (MW cut-off10.000 daltons) resulting in a retentate and an ultrafiltrate. SEC in DMSO H20 (90 10) 0.05 MLiBr according to (32).

Figure 3. The size-exclusion chromatographic separation of a standard protein mixture on a Hibar RT LiChrospher 500 DIOL column. COhimn size, 250 X 4 mm (2 columns) eluant, 50 mM H3PO4 adjusted to pH 7.0 with 2.0 M NaOH -r 1% SDS flow-rate, 0.2 ml/min pressure, 15 kg/cm chart speed, 2.5 mnVntin detection, UV 208 nraO.08 AUFS. Samples, (1) albumin (bovine serum = 68 (KK)) (2) chymo-trypsinogen A (25 000) (3) cytochrome c (12 500) (4) alanine (89).

However, in the absence of true identification of these complexes, it is not 100% possible to identify each of the complex peaks (20,59). Indeed, in none of the existing CE immunoaffinity studies reported have any Ab-Ag complexes been identified by light scattering or mass spectrometric methods (60a,b). This would require, for example, a size exclusion chromatographic (SEC) separation of a particular complex and then on-line characterization with isolation and reinjection under CZE conditions (60c). 

Figure 2.11 Schematic diagram of a gel permeation chromatograph (size exclusion chromatograph). The key elements are a pulseless pump, injection port, separation column containing appropriate crosslinked gel particles of controlled pore size, and one or more detector systems...

An analytical TREF system was first described by Wild and Ryle [8], Their system (Fig. 8) used components taken from a Waters model 200 size exclusion chromatograph. The solvent reservoir, degasser and pump from the Waters unit was used as was the refractive index detector system. In place of the SEC oven a temperature programmed oil bath provided the temperature gradients. A 0.2 g polymer sample was loaded in a hot trichlorobenzene solution into a small column packed with 40-60 mesh Chromosorb P. Crystallization was achieved by slow-cooling the polymer solution (0.2 g in 5 ml) in the packed column at a rate of 1.5 K/hour down to room temperature. The temperature rising elution was carried out at a flow rate of 6 ml/min and a rate of temperature rise of 8 K/hour. The refractive index response and the separation temperature were recorded continuously on a two-pen recorder. A calibration curve of methyl content vs. elution... 

By contrast with other chromatographic methods, GPC (gel permeation chromatography) or SEC (size exclusion chromatography) separates according to the size of the specimen molecule in solution. This is a simple way of utilizing the exclusion principle. This very specific separation mechanism enables the determination of molecular weight distribution and dispersion index. 

Examples of entropically driven separations are chiral separations and separations that are dominated by size exclusion. However, it must be emphasized that chromatographic separations can not be exclusively "energetically driven" or "entropically driven" but will always contain both components. It is by the careful adjustment of both "energetic" and "entropic" components of the distribution that very difficult and subtle separations can be accomplished. 

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