An innovative approach for separation and purification of natural products using carbon nanotube–alginate gel beads as a novel stationary phase

Carbon nanotube(CNT)–alginate gel beads were used as a novel stationary phase for the separation and purification of natural products in an open glass column. The objective of this study is to find a new packing material which can improve the separation efficiency and resolution in preparative or semi-preparative liquid chromatography. Four types of CNTs were evaluated for their adsorption and desorption capability of various natural compounds. Langmuir and Freundlich isotherms were used to correlate the solute affinity of CNTs towards alkaloids at different temperatures, and the Langmuir isotherm fit better. Static adsorption and desorption tests indicated that multi-walled carbon nanotube(MWCNT)-1 was suitable to separate alkaloids of Dature metel L. MWCNT-1 was then bonded to alginate carrier to form gel beads, which further improved the separation. Under gradient elution, the purity of atropin and anisodamine reached 83.6% (weight of atropin/weight of dry eluent) and 90.5%, respectively, which were 7.9-fold and 11.2-fold to those in control samples. The recovery yields were 88.2% and 89.2%, respectively. Therefore, alginate-supported CNTs gel beads can serve as an excellent liquid chromatographic packing material.