Retention size exclusion chromatography

The effects of various pore-size distributions, including Gaussian, rectangular distributions, and continuous power-law, coupled with an assumption of cylindrical pores and mass transfer resistance on chromatographic behavior, have been developed by Goto and McCoy [139]. This study utilized the method of moments to determine the effects of the various distributions on mean retention and band spreading in size exclusion chromatography. 

ISEC is a size-exclusion chromatography technique, in which the stationary phase is the CFP to be to characterized [16-18] and the eluates are geometrically well-defined steric probes. From the determined retention volumes in a given solvent and on the basis of suitable morphological models, ISEC analysis provides the... 

Fig. 51 The experimental curve of the molecular weight distribution of a PpPTA polymer dissolved in sulphuric acid determined with size-exclusion chromatography. The relation between molecular weight and retention time t (in minutes) 10log(Mw)=0.345-0.1321 1. The position of the vertical line at f=42 min corresponds with Mw=6,200... 

The data prove that the retention order of anthocyanins deviates from each other in HPLC and TLC suggesting the involvement of a different retention mechanism. It was stated that the preseparation of anthocyanins by size-exclusion chromatography is a prerequisite of the successful preparative separation by RP-HPLC [244],... 

Size exclusion chromatography (SEC), also known as gel permeation chromatography (GPC), was used for the separation and fractionation of macromolecules on an analytical and preparative scale [17]. The separation occurs predominantly by the hydrodynamic volume of the macromolecules in solution, however, in some cases the polarity of the molecules can also influence the retention times. Like HPLC, the SEC technique is generally very reproducible with regard to its elution times (typically < 1 h) and hence can be used for automated synthesis. But because the cost for an automated SEC system is high, it must be considered as a serial separation technique. In addition, larger scale separations > 100 mg, usually require repetitive injection of small aliquots. 

Calibration of size-exclusion chromatography columns based on the finding that the retention volume of a molecular or particulate species is usually a single-valued function of an appropriate size parameter of this molecule or particle, irrespective of its chemical nature and structure. 

Characteristic of the efficiency of a size-exclusion chromatography set-up in terms of band broadening, defined as N = (y la Y, where Fr is the retention volume of an individual low-molecular-weight compound, and oy is the corresponding full width at 60.7% peak height of the elution peak. 

The specific pore volume is important in size-exclusion chromatography (SEC) [10] because the separation takes place there. In retentive chromatography, it is necessary to provide the surface area... 

The separation of chemical species by size exclusion chromatography is more reproducible than any other type of chromatography. Once the SEC columns, the mobile phase (most often a pure solvent like THF or toluene), and the flow rate are selected, the retention volume (or retention time assuming the flow rate does not change) is primarily a function of linear molecular size, which can be obtained from the valence bond structure if the compound is known. Some of the chemical species can interact with the solvent forming complexes with an effective linear size greater than that of the molecule. This causes the expected retention volume, based on "free" molecular structure, to shift to a lower but very reproducible retention volume. Phenols in coal liquids form 1 1 complex with THF (9,10) and carry the effective linear molecular size to increase. As a result phenolic species elute sooner than expected from their... 

The role of size exclusion chromatography is the separation of rather complex coal liquids into simpler fractions. The retention volume can be used to help Identify the chemical structure where GC-MS is unable to identify its possible structure. For example biphenyl and dihydroacenaphthene have the same molecular formula as well as similar mass spectral fragmentation patterns. Coal liquids contain both species. The one which appears first (lower SEC retention volume) is biphenyl (GC ret. time = 17 min. in Figure 5-6). Dihydroacenaphthene appears later at longer SEC retention volume and is identified in Figure 5-12 at GC retention time of 13 minutes. The former has a longer structure compared to the latter. 

Dependence of Spreading Factor on the Retention Volume of Size Exclusion Chromatography... 

Size-exclusion chromatography can be used to analyze protein-protein interactions. Bloustine et al. (2003) presented a method to determine second virial coefficients (B2) of protein solutions from retention time measurements in size-exclusion... 

FIG. 1.23 Plot of log M and detector output versus retention volume for size-exclusion chromatography. Also shown is the relation among VR, Vv, VP, and K, Vp as discussed in the text. (Redrawn with permission of P. C. Hiemenz, Polymer Chemistry The Basic Concepts, Marcel Dekker, New York, NY, 1984.)... 

E. Watson and W. C. Kenney, Hydrophobic retention of proteins using high-performance size-exclusion chromatography, Biotechnol. Appl. Biochem., 70 551-554(1988). 

Ball, D. Thornton, T. "Advantages of Direct Measurement of Retention Volume in Liquid Chromatography and Size Exclusion Chromatography" 32nd Pittsburgh Conference on Analytical Chemistry and Applied Spectroscopy, Atlantic City, NJ, 1981 paper 357. 

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