In gel permeation chromatography

Salt Effects. The definition of a capacity factor k in hydrophobic interaction chromatography is analogous to the distribution coefficient, in gel permeation chromatography ... 

A novel cross-linked polystyrene-divinylbenzene copolymer has been produced from suspension polymerization with toluene as a diluent, having an average particle size of 2 to 50 /rm, with an exclusive molecular weight for the polystyrene standard from about 500 to 20,000 in gel-permeation chromatography. A process for preparing the PS-DVB copolymer by suspension polymerization in the presence of at least one free-radical polymerization initiator, such as 2,2 -azo-bis (2,4-dimethylvaleronitrile) with a half-life of about 2 to 60 min at 70°C, has been disclosed (78). 

The packing material for liquid chromatography is produced from styrene and divinylbenzene dissolved in 50 to 300% by weight of organic solvent to both monomers. The constitution of divinylbenzene in the monomer mixture is not less than 60% by weight. In gel-permeation chromatography, the exclusive molecular weight is not less than 1 X 10 in terms of standard polystyrene (79). 

Macroporous polyvinyl alcohol particles with a molecular weight cutoff of ca. 8 X 10 in gel-permeation chromatography have been prepared. The particles are produced by first dispersing an aqueous solution of polyvinyl alcohol in an organic solvent to make spheres of polyvinyl alcohol solution. Holding the dispersion in such a state that a gel will then form spontaneously will cause the gel to react with glutaraldehyde in the presence of an acidic catalyst (85). 

Rill, RL Van Winkle, DH Locke, BR, Templated Pores in Hydrogels for Improved Size Selectivity in Gel Permeation Chromatography, Analytical Chemistry 70, 2433, 1998. 

Some kinds of chromatography require relatively little optimization. In gel permeation chromatography, for example, once the pore size of the support and number of columns is selected, it is only rarely necessary to examine in depth factors such as solvent composition, temperature, and flow rate. Optimization of affinity chromatography is similarly straightforward. In RPLC or IEC, however, retention is a complex and sensitive function of mobile phase composition column type, efficiency, and length flow rate gradient rate and temperature. 

Casassa, E. R, Theoretical models for peak migration in gel permeation chromatography, /. Phys. Chem., 75, 3929, 1971. 

Slagowski, E. L., Fetters, L. J., and McIntyre, D., Upper molecular weight limit for the characterization of polystyrene in gel permeation chromatography,... 

Samay, G. and Kubin, M., Peak distortion in gel permeation chromatography at high sample concentration, /. Appl. Polym. Sci., 23, 1879, 1979. 

Viovy,J.-L. and LesecJ. Separation of Macromolecules in Gels Permeation Chromatography and Electrophoresis. Vol. 114, pp. 1-42. 

The major technical difficulty in gel permeation chromatography involves the careful packing of the column to ensure a uniform structure and it is absolutely essential that the level of the solvent is never allowed to fall below the level of the gel otherwise disruption of the gel bed occurs. Additionally, because most gels are compressible, only an absolute minimum of pressure should be applied to prevent alteration of the pore characteristics. In practice hydrostatic pressures greater that 30-40 cm should not be used and pumps should be used only with non-compressible gels. 

The effluent volume is the most convenient parameter to measure in gel permeation chromatography because flow rates are often variable, making the use of retention times unsuitable. The sequence of different solutes emerging from a column will therefore be reported as the total volume of solvent that has emerged from the column when the substance appears in the effluent (Ve). 

In gel permeation chromatography, the larger molecules are eluted from the column last... 

Shear Degradation of Very High Molecular Weight Polymers in Gel Permeation Chromatography... 

The chemical structure of PBS also may be altered by exposure to radiation and such changes may contribute to the solubility rate difference between an exposed and an unexposed PBS film. U-type films were prepared from unirradiated powders while IP-type films were prepared from irradiated powders. Inspection of Table II or Figure 2 shows that the three U-type films have slightly larger solubility rates than IP-type films of comparable M. The solubility rate differences between IP and U-type films are small relative to the differences between IP and IF type films. The solubility rate difference between a U and an IP film of comparable M must arise from chemical structural differences between irradiated and unirradiated powders. These radiation-induced changes may also be responsible for differences observed in the elution behavior between irradiated and unirradiated PBS samples in gel permeation chromatography experiments. Irradiated PBS samples yield abnormally broad elution curves while unirradiated samples elute normally I3.8I. 

The molybdenum-based catalyst MoOCl2(t-BuO)2 has been used to copolymerize norbornene and dicyclopentadiene (20). The polymeric product exhibits a single peak in gel permeation chromatography. 

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