Gel permeation/size exclusion

II. AMERICAN POLYMER GEL-PERMEATION/SIZE EXCLUSION CHROMATOGRAPHY (GPC/SEC) COLUMN REPACKING... 

Lipid removal Biobeads SX-3 Cyclohexane, dichloromethane Gel permeation (size exclusion)... 

In Fl-FFF, the channel is created by placing a mylar spacer with the channel cut out between two porous frits. A membrane hlter of a specihc molecular weight cutoff is placed on one of the frits and acts as the accumulation wall to permit flow, without loss of particles. The applied force is then a perpendicular flow of the carrier solution across the porous frits. Fl-FFF is a versatile technique capable of separating macromolecules as small as roughly 1000 Da, in which case it is comparable to gel permeation (size exclusion) chromatography. However, Fl-FFF can also be applied to the separation of colloidal particles. In this case the hydrodynamic diameter of the colloidal particle is related to the retention volume, V by the equation... 

Profile The company was founded in 1976 to develop techniques and instrumentation for the characterization of polymer systems, and to develop high-technology polymer products for chromatography, and for diagnostic and pharmaceutical applications. The company operates from offices in the USA, UK, and Europe. Primary products are in the specialized areas for gel permeation/size exclusion chromatography (GPC/SEC) including columns, standards, advanced high temperature systems and detectors, and GPC/SEC software. 

Modern liquid chromatography can be carried out in any of the classical modes, e.g., liquid-solid adsorption chromatography, liquid-liquid partition chromatography, reversed-phase chromatography, ion-exchange chromatography, and gel-permeation (size exclusion) chromatography. 

Sorption is the general term that refers to the interaction of a solute with the stationary phase, whether that interaction involves adsorption, ion-exchange, or gel permeation (size exclusion). When the relative concentrations of solute in the stationary and mobile phases are the same, independent of concentration (as is normally expected by reference to the of the solute), the peak shape will remain basically the same and will be symmetrical. This relationship, which describes amount of solute sorbed relative to concentration in mobile phase (at constant temperature), is the sorption isotherm. 

In this section we discuss the choice of a chromatographic system on the basis of, firstly, the type of stationary phase and, secondly, the composition of the eluent. A division in subsections is made from the kinds of stationary phases available, bearing in mind that the more specialized phases for ion-exchange, gel permeation (size exclusion), and bioaffinity chromatography are treated in separate chapters (4.5 to... 

H NMR spectra were recorded on Briiker ACP 400 or DPX 400 spectrometers using deuterated solvents obtained from CEA or Aldrich. Polymerization kinetics, followed by NMR, were recorded using the Briiker built-in kinetics software. Molecular mass analyses were carried out by gel permeation (size exclusion) chromatography on a Polymer Laboratories system. THF was the eluent at 1.0 mL min with a PL-gel 5 jim (50 X 7.5 mm) guard column, two PL-gel 5 pm (300 x 7.5 mm) mixed-C columns with a refractive index detector. Samples were compared against narrow standards of poly(methyl methacrylate), A/p = 200 to 1.577 x 10 g mol , obtained from Polymer Laboratories, except for methyl methacrylate dimer, trimer, and tetramer which were prepared by catalytic chain transfer polymerization at the University of Warwick. 

Gel permeation (size exclusion) hplc was performed on a Waters Protein PAK 300SW column, in a buffer containing lOOmM sodium phosphate (pH 7.0). 5pg of protein was injected. The flow was driven at 0.5 mg/ml by a Beckman HOB pump and controller, and the eluate monitored at 220nm using a Beckman 165 flow-through spectrophotometer. 

The most widely used method for determining molecular weight distribution for fiber forming polymers is gel permeation (size exclusion) chromatography (GPC or SEC). Other commonly used methods in this case are end group analysis, osmometry, and viscometry. These methods are also introduced below. 

---