Molecular mass determination by means of size-exclusion chromatography

3 MOLECULAR MASS DETERMINATION BY MEANS OF SIZE-EXCLUSION CHROMATOGRAPHY  

As elution volume is a function of molecular size and not directly of its mass, this comparison is only valid for the same type of molecules (e.g. homologues or polystyrenes in this particular case) in the same solvent  

Even the concentration of the sample solution can strongly influence both peak width and retention time.  

5 Chapter 8 of Striegel et al., see first page of this chapter. Anonymous, J. Chromatogr. Sci., 30, 66 (1992). 

The determination of molecular mass and molecular mass distribution by size-exclusion chromatography is rapid and easy. However, as it is based exclusively on elution volume, this latter must be determined extremely accurately. Elution volume is a function of log(molar mass) and hence even small errors in the determination of Ve have a dramatic effect. For this reason, either a pump which is both reproducible and precise plus thermostatic control of the system should be 

An unknown fraction can be characterized or the molecular mass distribution of a polymer material determined by comparing the sample chromatogram (Fig. 15.6, bottom) with the calibration graph (Fig. 15.6, centre). 

The determination of molecular mass and molecular mass distribution by size-exclusion chromatography is rapid and easy. However, as it is based exclusively on elution volume, this latter must be determined extremely 

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