4.3. Homogeneity and Molecular Weight of the Purified Fucoidan

The purity of SF fractions was determined by cellulose acetate membrane electrophoresis (CAME). Briefly, cellulose acetate membranes (2 × 8 cm) were immersed in 0.1 mol/L HCl solution for 30 min. After the excess buffer was removed, the electrophoresis was carried out under 2.5 V/cm, 0.4–0.6 mA/cm for 200 min. The membrane was stained with 0.2% Alcian blue solution containing 10% ethanol, 0.1% glacial acetic acid and 0.03 M MgCl₂ [50].

The molecular weights (Mw) of the purified fucoidans were determined by high performance liquid gel permeation chromatography (HPGPC) with a Shodex KS-804 column (8 mm × 300 mm, 7 μm) at 80 °C. Additionally, the sample was eluted with highly purified water at a flow rate of 0.5 mL/min. The molecular weight of polysaccharides was calculated by a standard curve obtained using dextran of 410, 270, 150, 50, 25, 5 kDa as reference standards.