Preparation, evaluation, and application of a novel reversed-phase/zwitterionic/hydrophilic interaction liquid chromatographic mixed-mode stationary phase

Dialdehyde cellulose-based mixed-mode stationary phases for diversified high-performance liquid chromatography separations

To deal with complicated separation situations, this study successfully prepared two mixed-mode chromatography (MMC) stationary phases, CCL-SIL and PCL-SIL, by functionalizing dialdehyde cellulose (DAC) derivatives. In liquid chromatography applications, CCL-SIL exhibited superior separation performance for nucleosides and bases in HILIC mode, while PCL-SIL performed better in RPLC and IEC modes. Their distinct separation mechanisms were also elucidated by quantum chemical calculations. Both CCL-SIL and PCL-SIL showed good stability and reproducibility, with relative standard deviations of retention time, peak area, and peak height below 7.79 % and 4.37 % for multiple injections. Particularly, the PCL-SIL column and the CCL-SIL column were successfully used for the quantitative analysis of trace targets in real samples with complex matrix, demonstrating high accuracy and precision.

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.