C18-COOH Silica: Preparation, Characterisation and Its Application in Purification of Quaternary Ammonium Alkaloids from Coptis chinensis

Developing magnetic functionalized dendritic fibrous mesoporous silica as advanced adsorbent for quaternary ammonium alkaloids

A novel π-conjugated polymer-modified magnetic dendritic fibrous mesoporous silica adsorbent (MB@KCC-1@π-CP) is reported for the accurate determination of quaternary ammonium alkaloids (QAAs) in complex body fluid matrices. It is demonstrated that the magnetic dendritic fibrous mesoporous silica (MB@KCC-1) is an excellent carrier combining magnetism, high specific surface area, unique hierarchical pore structure, and fast mass transfer rate. The π-conjugated polymer (π-CP) can efficiently retain QAAs (berberine, coptisine, palmatine, jatrorrhizine) by multiple interactions. In addition, the adsorption kinetics and adsorption mechanism were also studied and discussed. Under optimized extraction conditions, MB@KCC-1@π-CP-based magnetic solid-phase extraction (MSPE) and high-performance liquid chromatography (HPLC) method affords a wide linear range (0.5-20000 ng mL-1), low limits of detection (0.2-2 ng mL-1), and satisfactory relative standard deviations (RSD) of inter-day (< 2.4%) and intra-day (< 3.1%) for QAAs. Trace QAAs in complex human blood plasma samples were successfully detected by the established method.

A vortex-enhanced magnetic solid phase extraction for the selective enrichment of four quaternary ammonium alkaloids from Zanthoxyli Radix

Zanthoxyli Radix, the dried root of Zanthozylum nitidum (Roxb.) DC, one of traditional Chinese medicines (TCMs), exhibits various pharmacological activities such as anti-bacterial, anti-inflammatory, anti-tumor, analgesic activity. A sustainable vortex-enhanced magnetic solid phase extraction (VE-MSPE) method combined with ultra-high performance liquid chromatography (UHPLC) was established to enrich and analyze the bioactive quaternary ammonium alkaloids (QAAs) of Zanthoxyli Radix. Fe₃O₄@C@CMCS magnetic nanoparticles (MNPs) was first synthesized for selectively adsorbing target QAAs (magnolinine, sanguinarine, nitidine chloride and chelerythrine), which possess excellent adsorption performance after being reused 10 times. The results revealed that the great adsorption rate of Fe₃O₄@C@CMCS MNPs for the four QAAs could reach 55.1-78.7 %. In addition, a reliable linear relationship (r ≥ 0.9995) and good recovery (97.5-104 %) was obtained. Consequently, the VE-MSPE method applying Fe₃O₄@C@CMCS MNPs as a sustainable adsorbent exhibited great potential in the selective enrichment of QAAs in TCM.

Liquid chromatographic separation of alkaloids in herbal medicines: Current status and perspectives

Alkaloids are a widespread group of basic compounds in herbal medicines and have attracted great interest due to various pharmaceutical activities and desirable druggability. Their distinctive structures make chromatographic separation fairly difficult. Peak tailing, poor resolution, and inferior column-to-column reproducibility are common obstacles to overcome. In order to provide a valuable reference, the methodologies and/or strategies on liquid chromatographic separation of alkaloids in herbal medicines proposed from 2012 to 2019 are thoroughly summarized.

Recent advances in mixed-mode chromatographic stationary phases

Mixed-mode phases have become very popular in the last decade, and the number of new mixed/multi-mode sorbents is growing fast. Unlike single-mode stationary phases, perfectly suited for the separation of the analytes possessing similar physicochemical properties, for instance reversed-phase chromatography for hydrophobic solutes, mixed-mode sorbents providing multimodal interactions can render better separation selectivity for complex mixtures of solutes differing significantly in their physicochemical characteristics. The most frequent modern mixed-mode stationary phases are di/tri-mode sorbents embracing the following interactions, hydrophobic, electrostatic (coulombic), and hydrophilic. According to their structures, it is possible to distinguish silica-based, polymer-based, hybrid, and monolithic mixed-mode stationary phases. Herewith, newly synthesized mixed-mode sorbents developed within the last two and half years are categorized, discussed, and summarized. The main attention is devoted to the description of the synthetic routes and characterization methods applied for the new stationary phases.

Modification and Characterization of Fe₃O₄ Nanoparticles for Use in Adsorption of Alkaloids

Magnetite (Fe₃O₄) is a ferromagnetic iron oxide of both Fe(II) and Fe(III), prepared by FeCl₂ and FeCl₃. XRD was used for the confirmation of Fe₃O₄. Via the modification of Tetraethyl orthosilicate (TEOS), (3-Aminopropyl)trimethoxysilane (APTMS), and Alginate (AA), Fe₃O₄@SiO₂, Fe₃O₄@SiO₂-NH₂, and Fe₃O₄@SiO₂-NH₂-AA nanoparticles could be obtained, and IR and SEM were used for the characterizations. Alkaloid adsorption experiments exhibited that, as for Palmatine and Berberine, the most adsorption could be obtained at pH 8 when the adsorption time was 6 min. The adsorption percentage of Palmatine was 22.2%, and the adsorption percentage of Berberine was 23.6% at pH 8. Considering the effect of adsorption time on liquid phase system, the adsorption conditions of 8 min has been chosen when pH 7 was used. The adsorption percentage of Palmatine was 8.67%, and the adsorption percentage of Berberine was 7.25%. Considering the above conditions, pH 8 and the adsorption time of 8min could be chosen for further uses.