3.5. Molecular Weight Distribution

Determination of the molecular weight distribution of the fucoidan was performed by high performance gel permeation chromatography (HPGPC). An Agilent 1260 HPLC system (Agilent, Santa Clara, CA, USA) was used, including a Refractive Index Detector (RID, DEAA602884), a Variable Wavelength Detector (VWD, DEABB05037), and an Ultrahydrogel^TM Linear column (7.8 mm × 300 mm) (Waters, Milford, MA, USA). The column was maintained at 35 ± 0.1 °C. The mobile phase was NaNO₃/0.02% NaN₃ (0.1 M), and the flow rate was 0.6 mL/min. The polysaccharides molecular weight distribution was calculated from the calibration curve provided by a series of dextran standards (T-10, T-40, T-70, T-500 and T-2000). They were bought from Pharmacia Biotech (Uppsala, Sweden). All other solvents and chemicals used were of the analytical reagent grade and were bought from Sinopharm Chemical Reagent Co., Ltd. (Shanghai, China). The wavelength was 280 nm for both RID and VWD.