ZIF-8@SiO2 based novel dispersive solid-phase filter extraction technique for the purification of laminarin and fucoidan from undaria pinnatifida

Laminarin and fucoidan belong to seaweed polysaccharides, which are abundant in kelp, such as undaria pinnatifida, and have a variety of beneficial pharmacological activities. This study developed a dispersive solid-phase filter extraction (DSPFE) method by combining the high mass transfer efficiency of traditional dispersive solid-phase extraction (DSPE) with the timesaving and convenient advantages of filter solid-phase extraction (FSPE). Although the surface interactions enable ZIF-8 to separate large molecules, the small particle size of ZIF-8 generates ultrahigh pressures during solid-phase extraction (SPE). Hence, a large particle size of [email protected]2 can be obtained by growing ZIF-8 on SiO2. Using [email protected]2 as the adsorbent for DSPFE combined with high-performance size exclusion chromatography (HPSEC), the conditions of vortex-assisted DSPFE were optimized to realize the economic (adsorbent amount: 5 mg), rapid (extraction time: 10 min), and efficient (recovery: 88.5–91.1%) extraction and analysis of laminarin and fucoidan in undaria pinnatifida. The adsorption process followed Freundlich isotherm (R2 ≥ 0.9792) and pseudo-second-order kinetics (R2 ≥ 0.9870). The proposed method showed good linearity (0.01–2 mg/mL, R2 ≥ 0.9990), limit of detection (0.027–0.114 mg/mL), limit of quantitation (0.089–0.379 mg/mL), accuracy (93.4–104.7%), and precision (2.2–5.6%).