Question

1-Discuss the differences between size exclution chromatography and hydrodynamic chromatography ?

2- When would you use each of these?

Answer 1

Size-exclusion chromatography (SEC) is a chromatographic method in which molecules in solution are separated by their size, and in some cases molecular weight.^[1] It is usually applied to large molecules or macromolecular complexes such as proteins and industrial polymers. Typically, when an aqueous solution is used to transport the sample through the column, the technique is known as gel-filtration chromatography, versus the name gel permeation chromatography, which is used when an organic solvent is used as a mobile phase. SEC is a widely used polymer characterization method because of its ability to provide good molar mass distribution (Mw) results for polymers.

Hydrodynamic chromatography (HDC) has experienced a resurgence in recent years for particle and polymer characterization, principally because of its coupling to a multiplicity of physical detection methods. When coupled to light scattering (both multiangle static and quasi-elastic), viscometric, and refractometric detectors, HDC can determine the molar mass, size, shape, and structure of colloidal analytes continuously and as a function of one another, all in a single analysis. In so doing, it exposes the analytes to less shear force (and, hence, less potential for flow-induced degradation) than in, for instance, size-exclusion chromatography.

When colloidal materials are carried in aqueous suspension through packed beds of spherical particles, it has been observed that the rate of transport of the colloidal particles depends on such factors as the size of the colloid, the size of the packing and the ionic composition of the aqueous phase. From such observations, a chromatographic technique has been developed, called hydrodynamic chromatography, which can yield size information on a variety of colloidal materials in the submicron range.