Using OMNISEC Triple-Detection GPC to Determine Structure of Dextrans and Other Polysaccharides

Using OMNISEC Triple-Detection GPC to Determine Structure of Dextrans and Other Polysaccharides

This application note describes the analysis of a series of dextran samples ranging in molecular weight from about 1 – 650 kDa. Structural comparisons to other polysaccharides, gum arabic and pectin are presented.

Introduction

Initially discovered by Louis Pasteur in 1861, dextran is a polysaccharide that has found a variety of applications, primarily in the medical field, due to its minimal side-effects and solubility in aqueous media. These applications range from eye drop lubricants to intravenous solution components for parenteral nutrition and antithrombotic agents that reduce blood viscosity and prevent blood clotting. In the context of these medicinal applications, the molecular weight of each dextran sample dictates its behavior. For example, dextran samples with molecular weights greater than 60 kDa are not easily removed from the blood, and thus exhibit blood thinning effects for a longer period of time than lower molecular weight versions. Recently, the most common dextran for anticoagulation therapy has been dextran-40, with a molecular weight of 40 kDa.

A rare but potential negative side-effect of dextran is acute renal failure, which is possibly influenced by the dextran’s intrinsic viscosity, and thus its structure. As such, the accurate analysis and molecular weight characterization of dextran samples is critical.

Gel permeation chromatography (GPC) or, equivalently, size-exclusion chromatography (SEC) is a widely used technique to characterize a wide variety of macromolecules, from bulk synthetic polymers to natural polymers and proteins. This technique can be used to measure the molecular weight moments, molecular weight distribution, intrinsic viscosity and hydrodynamic size of these macromolecules. Figure 1 shows a complete setup for a GPC/SEC system.