Preparation of a stationary phase with quaternary ammonium embedded group for selective separation of alkaloids based on ion-exclusion interaction.

A stationary phase (named QA C10) with quaternary ammonium embedded between a propyl and a decyl chain was synthesized by immobilization of N,N-dimethyldecylamine on chloropropyl-silica surface. A set of representative neutral, basic, and acidic compounds was employed to evaluate its chromatographic properties. The results illustrated that QA C10 was a mixed-mode stationary phase possessing both hydrophobic and ionic characteristics. The QA C10 stationary phase was further used for selective separation of alkaloids from Cortex phellodendri. Under acidic condition, alkaloids could be eluted in first 8 min, while other neutral and acidic fractions were retained better on QA C10 column. Then, obtained alkaloid fraction was analyzed by LC-MS/MS and 22 alkaloids were identified. Our study confirmed the advantages and application potential of the QA C10 stationary phase for alkaloids separation.

A novel ionic-bonded cellulose stationary phase for saccharide separation.

A hydrophilic interaction liquid chromatography (HILIC) stationary phase of cellulose-coated silica was synthesized as a novel saccharide separation material. The material, prepared with a method based on ionic interaction, was demonstrated to be efficient for immobilization of saccharides on silica supports. The method is more efficient than traditional immobilized saccharide stationary phase synthesis methods. It was evolved from a method using anion exchanger microparticles agglomerated onto macroparticles of cation exchangers to produce anion exchangers. Cationic cellulose, which has a large number of hydroxyl groups, was immobilized on sulfonated silica. The cellulose-coated stationary phase we designed used strong hydrogen bonding between cellulose hydroxyl and carbohydrate compounds for HILIC retention and separation. The stationary phase was successfully used to separate the samples of polar compounds and the complex samples of oligosaccharides, and demonstrated good reproducibility and stability. The material exhibited good separation selectivity for carbohydrates and ability to enrich glycosylated peptides. The method described here is easy to achieve, environmentally safe and innovative than other methods. It also has extensive application possibilities to separate other categories polar compounds.