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Size exclusion chromatography


Die Size Exclusion Chromatography (SEC, or Gel Permeation Chromatography GPC) is the most common method for polymer analysis. In this process the polymer is solved in an eluent and fractionated in a separation column, which is filled with porous material. By means of different detectors the polymer can be analysed. The column material consists normally of highly cross-linked PS latex particles, whereupon the pores have a broad size distribution. The fractionation of the polymer only bases on geometric pore effects, i.e. for this process the separation parameter is the hydrodynamic volume of the polymer.

Separation principle GPC/SEC

Separation principle of the Size Exclusion Chromatography SEC (GPC)


The Size Exclusion Chromatography SEC is a relative method. For the establishment of a calibration curve you need narrowly distributed polymer samples, whereby the elugramms of these polymers can be converted into their molecular weight distributions. By means of the universal calibration, which uses the Kuhn-Mark-Houwink-relation (correlation between hydrodynamic volume, intrinsic viscosity, and molecular weight), it is possible to produce calibration curves for other polymers. Thereby also for polymers, which are not available as narrowly distributed standards, molecular weights can be determinated.


In the following the specifications of our SEC/GPC-apparatuses are listed:

Aqueous SEC/GPC

  • Analyte: Polyelektrolytes, non-ionic water soluble polymers, Polysaccharides

  • Sample amount ~ 100 mg

  • Molecular weight range: 1 - 1,000 kg/mol

  • Eluent: aqueous saline solution, if necessary MeOH/H2O mixture

  • Detectors: UV-Detector, RI-Detector

  • Conventional calibration with dextran

Þ  Average molecular weight (Mw, Mn), Polydispersity PDI

  • Universal calibration by means of viscometry

Þ  Mw, Mn and PDI for more polymers accessible



Organic SEC/GPC

  • Analyte: in THF or Toluene soluble polymers

  • Sample amount ~ 100 mg

  • Molecular weight range: 1 - 1,000 kg/mol

  • Eluent:Tetrahydrofuran (THF), Toluene

  • Detectors: UV-Detector, RI-Detector

  • Conventional calibration with polystyrene, poly methyl methacrylat

Þ  Average molecular weight (Mw, Mn), Polydispersity PDI

  • Universal calibration by means of viscometry

Þ  Mw, Mn and PDI for more polymers accessible




Analysis
 
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