Natural polysaccharides are important active biomolecules. However, the analysis and structural characterization of polysaccharides are challenging tasks that often require multiple techniques and maps to reflect their structural features. This study aimed to propose a new heart-cutting two-dimensional liquid chromatography (2D-LC) method for separating and analyzing polysaccharides to explore the multidimensional information of polysaccharide structure in a single map. That is, the first-dimension liquid chromatography (1D-LC) presents molecular-weight information, and the second-dimension liquid chromatography (2D-LC) shows the fingerprints of polysaccharides. In this 2D-LC system, the size-exclusion chromatography-hydrophilic interaction chromatography (SEC-HILIC) model was established. Coupling with a charged aerosol detector (CAD) eliminated the need for the derivatization of the polysaccharide sample, allowing the whole process to be completed within 80 min. The methods were all validated in terms of precision, linearity, stability, and repeatability. The capability of the new 2D-LC method was demonstrated in determining various species of natural polysaccharides. Our experimental data demonstrated the feasibility of the whole systematic approach, opening the door for further applications in the field of natural polysaccharide analysis.
Keywords: Dendrobium; SEC–HILIC; charged aerosol detector; heart-cutting 2D–LC; polysaccharides; structural characterization.