Größenausschluß

Größenausschluß, also known as size exclusion or gel permeation chromatography, is a technique used primarily in biochemistry and analytical chemistry to separate molecules based on their size. The method relies on a porous stationary phase, typically composed of cross-linked polymer beads, which allows smaller molecules to penetrate deeply into the pores while larger molecules are excluded from the internal volume. As a result, larger molecules elute first, followed by progressively smaller ones, creating a separation based on hydrodynamic volume rather than molecular weight alone.

This technique is widely applied in the purification and characterization of biomolecules such as proteins, nucleic acids, and polysaccharides. It is particularly useful for determining molecular weight distributions, estimating protein folding states, and removing aggregates or contaminants from samples. Größenausschluß chromatography operates under isocratic conditions, meaning the mobile phase composition remains constant throughout the separation process, which simplifies analysis compared to other chromatographic methods.

The efficiency of size exclusion depends on factors such as the pore size distribution of the stationary phase, flow rate, and sample concentration. Columns used in this technique are often packed with spherical beads of uniform size to ensure consistent flow dynamics. While Größenausschluß is not as high-resolution as techniques like high-performance liquid chromatography (HPLC), it is valued for its simplicity and ability to handle large sample volumes without significant loss of resolution.

In addition to analytical applications, size exclusion chromatography is also employed in preparative scale separations, where it can be used to isolate specific molecular species from complex mixtures. The method is compatible with various detection techniques, including UV-Vis, refractive index, and multi-angle light scattering, enabling comprehensive characterization of separated components.