Fucoidan is a sulfated polysaccharide molecule found in some members of the Phaeophyceae (brown algae). It is the presence of the sulfate group on the fucoidan molecule that gives fucoidan its unique properties. Another component of fucoidan is the fucose group. Any valid fucoidan analysis would have to be based on a specific component of the fucoidan molecule, either the fucose or sulfate group.
However, analysis by means of the fucose group would be unreliable as fucoidan is not the only fucose-containing material in the Phaeophyceae. Therefore the sulfate group is the most accurate group to test for.
The most common analyses for sulfated polysaccharides are based on reaction with a strong amine group. Typical agents are benzalkonium or alkyl pyridinium compounds, dyes such as methylene blue or toluidine blue. The fucoidan analysis method used by MOLAB, methylene blue precipitation, is internationally recognized as one of the standard methods used to specifically determine the presence of sulfated polysaccharides.
It is important to note that non-sulfate-specific methods of analysis such as size-exclusion chromatography are not recognized as a valid method of testing for fucoidan.
Although size-exclusion chromatography can be used to determine soluble polysaccharides, it is not sulfate-specific therefore it does not distinguish between materials such as soluble pectins and fucoidan. Therefore non-fucoidan material may give a similar response to fucoidan when analyzed by size-exclusion chromatography or another non-fucoidan-specific analysis method.