Molar mass determination permeation chromatography

Gel permeation chromatography (GPC) is a widely used technique for determining molar mass and molar mass distrihution of polymers. In its usual form it is not an absolute method, though hy making the appropriate measurements it may be made to be so. 

Fig. 3.4. Determination of Vo and Vt by gel permeation chromatography. Dashed line dextran blue (defines void volume Vo) dotted line DNP-alanine (defines total volume Vt). Inset plot of a calibration curve for determination of molar mass...

Forss, K. Kokkonen, R. Sagfors, P.-E. Determination of the Molar Mass Distribution of Lignins by Gel Permeation Chromatography ACS Symp. Ser. 1989, this volume. 

Determination of the Molar Mass Distribution of Lignins by Gel Permeation Chromatography... 

It has been shown that the molar mass distributions of lignin sulfonates and kraft lignin can be determined by gel permeation chromatography. Calibration of the columns with lignin sulfonates of known molar mass or, alternatively, with commercially available proteins and polypeptides has been shown to give the same result. 

A chromatographic technique frequently used in polymer and dendrimer analysis is size exclusion chromatography (SEC) [13], which is often also called gel permeation chromatography (GPC). It is a straightforward method of determining the relative molar mass, the molar mass distribution, and the polydispersity index (PDI) with compatively modest consumption of material and time. 

For determining the molar mass of branched polymers gel permeation chromatography can be used. An important quantity in this connection is the hydrodynamic volume of the polymer coil, which, as shown before in Eq. (9.27), is proportional to the product [rj M. According to Benoit and co-workers (1966) the hydrodynamic volume is the key size parameter in the establishment of a universal calibration curve for gel permeation chromatography columns (see Chap. 2) if log (h/]M) is plotted versus the elution volume for a variety of polymers, the data fit a single curve. 

Gel permeation chromatography (GPC) is the established method for the determination of molar mass averages and the molar mass distributions of polymers. GPC retention is based on the separation of macromolecules in solution by molecular sizes and, therefore, requires a molar mass calibration to transform elution time or elution volume into molar mass information. This kind of calibration is typically performed with narrow molecular mass distribution polymer standards, universal, or broad calibration methods or molar-mass-sensitive detectors like light-scattering or viscosity detectors. 

The molar mass distribution can also be determined by gel permeation chromatography. In this method a solution of a polymer is forced through a gel that contains a... 

Bartells, H. Hallensleben, M.L. Pampus, G. Scholz, G. Molar mass distribution determination of natural rubber and masticated natural rubber by gel permeation chromatography. Angew. Makromol. Chem. 1990,... 

In many cases distribution functions are determined experimentally the characterization of petroleum fractions by true-boiling-point distillation or gas-chromatographically simulated distillation, and the characterization of polymers by gel-permeation chromatography. In principle, the integrals of continuous thermodynamics may be directly solved based on these experimentally determined distribution functions. However, this approach delicate numerical analyses and the assumption the complete distribution function has been obtained by experiment clearly this is no the case, for example, for some polymers only molar-mass averages are determined. Thus, there are numerous cases where smoothed or analytical distribution function provides more reliable phase equilibrium calculation than those obtained by use of the experimentally determined distribution function. When the integrals of continuous thermodynamics possess analytical solutions considerably numerical simplification is afforded and this is one motive for the desire to have analytical expressions for the distribution function. 

The number average molar mass, Mn, and the polydispersity index, Mw/Mn, for the Pis (Table 1) were determined by gel permeation chromatography (GPQ measurements in N,N-dimethylformamide (DMF), on a PL EMD-950 evaporative tight scattering detector apparatus. Considering that the polymerization degrees of the PAAs and of the... 

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