Gel permeation chromatographic methods

As was previously determined with CdS, titration experiments of sulfide produced varying sizes of ZnS nanoparticles. By maintaining a constant ratio between cysteine and Zn (II) of 1 1, varying equivalents of sulfide (0-1.5eq.) were added. From UV-vis, the collection of ZnS-(Cys) nanocrystals displayed absorption shoulders between 260-275 nm. As the equivalents of sulfide increased, the shoulder red shifted indicating the formation of larger nanoparticles in solution. Additional characterization by Mehra et al. of the ZnS nanocrystal products revealed only a small variation of particle sizes obtained after separation of the reaction mixtme by gel permeation chromatographic methods. ... 

Anonymous (1992). Report of two co-operative trials of a gel permeation chromatographic method for the i.solation of pesticide residues from oils and fats. An ily.st 117, 1451-1455. 

This gel permeation chromatographic method determines a range of amine antioxidants and antidegredants in rubbers in amounts down to 0.02%. 

Standard Test Method for Molecular Weight Averages and Molecular Weight Distribution of Certain Polymers by Liquid Size-Exclusion Chromatography (Gel Permeation Chromatograph -GPC) Using Universal Calibration" ASTM D 3593 80, Annual Book of ASTM Standards, ASTM, Philadelphia, PA, revised annually. 

A more sensitive viscometer than the drop-time glass capillary method is also needed in size exclusion chromatography (SEC) such as the gel permeation chromatographic (GPC) analysis of polymer molecular weight distribution (MWD). In an SEC system, a concentration detector is commonly used for providing the weight concentration profile of the polymer elution curve. 

Anderson [25] determined the distribution of olefinic bonds in elastomers after derivitization with 2,4-dinitrobenzenesulfonyl chloride using a gel permeation chromatograph equipped with a photometer operating at 254 nm. It is also possible to determine olefinic linkages with a preliminary epoxidation, followed by a method to analyze for the epoxy [26],... 

Gel permeation chromatographic (GPC) analysis was not possible directly on the primary-amine-functionalized oligomers because of their tendency to be adsorbed on the GPC columns rather than to elute. A method has been developed in our laboratories (9, 10) for derivatization of the amine end groups with benzophenone to form an imine functionality. This method allows FPC (fixed-partial-charge) analysis of the oligomers. 

Calculated from gel-permeation chromatographic data.6 — Indicates not specified. Calculated by the ultracentrifugation method (M.W. = 23.9 x 10s from the amino acid composition). 

However, fractional separation has been the basis for most asphalt composition analysis (Fig. 15.5). The separation methods that have been used divide asphalt into operationally defined fractions. Three types of asphalt separation procedures are now in use (a) chemical precipitation in which n-pentane separation of asphaltenes is followed by chemical precipitation of other fractions with sulfuric acid of increasing concentration (ASTM D-2006) (b) adsorption chromatography with a clay-gel procedure in which, after removal of the asphaltenes, the remaining constituents are separated by selective adsorption/desorption on an adsorbent (ASTM D-2007 and ASTM D-4124) and (c) size exclusion chromatography in which gel permeation chromatographic (GPC) separation of asphalt constituents occurs based on their associated sizes in dilute solutions (ASTM D-3593). 

A method for the gel permeation chromatographic analysis of the molecular weight distribution of wood pulp holocellulose as the carbanilate derivative has been applied to red maple Acer rubrum) and loblolly pine Pinus taeda). Either the chlorine-ethanolamine or acid-chlorite method could be used to prepare the holocellulose and the derivative was obtained by heating at 80 with phenylisocyanate in pyridine. Higher temperatures caused depolymerization. 

A reliable chromatographic method has been developed for the quantitative aneilysis of hydrophobic impurities in water-soluble polymeric dyes. The method utilizes both the molecular sieve effect of normal gel permeation chromatography and solute-column packing interaction, modified by solvent composition. This method eliminates the need to extract the impurities from the polymeric dye with 100 extraction efficiency, as would be required for an ordinary liquid chromatographic analysis. 

SEC or gel permeation chromatography (GPC) is one of the widely used chromatographic techniques [56,57]. In contrast to the already discussed colligative and scattering methods it is not an absolute method and requires proper calibration with some known polymer standards. One obtains not only the average molar masses (M , Mw, Mz) but the complete molar mass distributions. 

Since the technique was introduced (JJ in 1964, gel permeation chromatography (GPC), or size exclusion chromatography (SEC), has played an increasingly important role for the characterisation of polymers. The theory and practice of this chromatographic method have been extensively reported and a comprehensive text has recently been published on modern size exclusion chromatography (2). 

ISEC, which was introduced by Halasz and Martin in 1978 [119], represents a simple and fast method for the determination of the pore volnme, the pore size distribution profile, and the spe-cihc snrface area of porous solids. Generally, ISEC is based on the principle of SEC. SEC, also referred to as gel permeation or gel filtration chromatography, is a noninteractive chromatographic method that separates analytes according to their size by employing a stationary phase that exhibits a well-dehned pore distribution. 

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