Immobilized strychnine as a new chiral stationary phase for HPLC

Abstract

A new ion-exchanger type chiral stationary phase for high-performance liquid chromatography was prepared. The synthetic protocol is based on derivatization of silica with (3-iodopropyl)trimethoxysilane in the first step followed by immobilization of strychnine via quaternization of nitrogen atom of the alkaloid strychnine. The synthesized chiral stationary phase was chromatographically characterized. The main effort was headed towards the evaluation of the enantioselectivity of the novel sorbent. For that purpose a set of suitable chiral probes, specifically, binaphthyl derivatives, was employed. The influence of methanol content, concentration of aqueous ammonium acetate buffer, and its pH on retention factors, separation selectivity, and resolution of the atropoisomers of the mentioned chiral solutes was studied in detail. It was demonstrated that the new chiral stationary phase was capable to separate atropoisomers of four out of seven testing compounds. Despite the strong influence of the above mentioned variables on retention, their impact on selectivity and resolution was rather moderate. Concerning retention mechanism, it seems that electrostatic interaction between the positively charged quaternary nitrogen of the chiral stationary phase and anionic solute participates significantly in the retention process.

A new chiral stationary phase based on noscapine: Synthesis, enantioseparation, and docking study

“…The synthesis and study of functionalization of CSPs with desired active sites are interesting and also challenging, as is discussed in our reports from a microcolumn to a semipreparative column. 13,14 There has been a progressive effort to develop more efficient and economical chiral stationary phases that introduced alkaloid-based chiral selectors such as cinchona, [15][16][17] brucine, 18 strychnine, 19 codeine, 20 and antibiotic degradation products such as vancomycin. 13,[21][22][23] Although these efforts were effective and resulted in potentially versatile selectors, there is a long way to meet the pharmaceutical companies' demand for the suitable chiral LC column from a commercial and strategic point of view.…”

Macrocyclic glycopeptide‐based chiral selectors for enantioseparation in sub/supercritical fluid chromatography

“…Nowadays, SFC becomes more and more popular due to its properties, for example, short analysis time due to the possibility of high flow rate use, the high chromatographic efficiency due to the low mobile phase viscosity, the lower cost and toxicity of mobile phase, 4 progress in hyphenation with mass spectrometry, 5–7 and improvement in general understanding of its retention/separation mechanism 8–11 . Commercially available chiral stationary phases (CSPs) are based on a number of different chiral selectors including: polysaccharides, macrocyclic glycopeptides, cyclodextrins, cyclofructans, ion‐exchangers, Pirkle type, ligand exchangers, crown ethers, and chiral polymers 12–16 …”

“… 8 , 9 , 10 , 11 Commercially available chiral stationary phases (CSPs) are based on a number of different chiral selectors including: polysaccharides, macrocyclic glycopeptides, cyclodextrins, cyclofructans, ion‐exchangers, Pirkle type, ligand exchangers, crown ethers, and chiral polymers. 12 , 13 , 14 , 15 , 16 …”