Retention process in reversed phase TLC systems with polar bonded stationary phases

2005 ◽  
Vol 28 (6) ◽  
pp. 566-574 ◽  
Author(s):  
Wojciech Zapała ◽  
Monika Waksmundzka-Hajnos
Keyword(s):  
Stationary Phases ◽  
Reversed Phase ◽  
Bonded Stationary Phases

scholarly journals Liquid chromatographic enantioseparation of thalidomide and its derivatives on cyclodextrin-bonded stationary phases

2018 ◽  
Vol 91 (2) ◽  
pp. 99-106
Author(s):  
Szabó-Zoltán István ◽  
Foroughbakhshfasaei Mohammadhassan ◽  
Dobó Máté ◽  
Noszál Béla ◽  
Tóth Gergő
Keyword(s):  
Acetic Acid ◽  
Stationary Phase ◽  
Flow Rate ◽  
Chiral Separation ◽  
Stationary Phases ◽  
Reversed Phase ◽  
Chiral Separations ◽  
Column Temperature ◽  
Bonded Stationary Phases ◽  
Chiral Interactions

Abstract The chiral separation of three racemic immunomodulatory drugs, thalidomide, pomalidomide and lenalidomide was studied, using three cyclodextrin bonded stationary phases (β-, hydroxypropyl-β- and carboxymethyl-β-CD) in reversed-phase and polar organic mode. In polar organic mode, using acetonitrile and methanol, no chiral separation was observed. In reversed-phase mode pomalidomide showed chiral interactions with all selectors, while lenalidomide showed no chiral interactions with any of the cyclodextrins employed. Thalidomide showed chiral interactions with β-and carboxymethyl-β-CD, only. Based on these observations it can be concluded that the oxo group at position two is necessary for chiral recognition, while the aromatic primary amine group enhances it. Orthogonal experimental design was used to investigate the effect of the eluent composition, flow rate, and the column temperature on chiral separation. Concentration of the organic modifier was the most important factor among the investigated three variables showing high impact on the chiral separations. In the case of thalidomide optimized parameters (β-cyclodextrin-based stationary phase, 0.1% acetic acid/acetonitrile 95/5 (v/v), 5 °C column temperature, 0.6 ml/min flow rate) resulted in a resolution of 1.68 ± 0.02 between enantiomers. For pomalidomide, this value was 2.70 ± 0.02, under the circumstances as follows: β-cyclodextrin-based stationary phase, 0.1% acetic acid/acetonitrile 90/10 (v/v), 15 °C column temperature and 0.8 mL/min flow rate. Utilizing the experimental conditions employed on an LC-MS/MS system, concentrations as low as 2 ng/mL could be determined from mouse plasma for both substances. Elution sequences were determined with enantiopure standards and in both cases the R-enantiomers eluted first. The methods developed are suitable for the chiral separation of the abovementioned compounds and are sound starting points for bioanalytical method development.

Selective separation of xanthones and saponins from the rhizomes of Anemarrhena asphodeloides by modulating the density of surface charges in C18-bonded stationary phases

2017 ◽  
Vol 9 (38) ◽  
pp. 5604-5610 ◽  
Author(s):  
Jianfeng Cai ◽  
Huaxia Xin ◽  
Lingping Cheng ◽  
Zhimou Guo ◽  
Jiatao Feng ◽  
...  
Keyword(s):  
Stationary Phase ◽  
Stationary Phases ◽  
Reversed Phase ◽  
Selective Separation ◽  
Separation Method ◽  
Surface Charges ◽  
Bonded Stationary Phases ◽  
Robust Separation ◽  
Anemarrhena Asphodeloides ◽  
Positively Charged

A rapid and robust separation method based on the positively charged reversed-phase (PGRP) stationary phase was developed for selective separation of saponins and xanthones from the rhizomes of Anemarrhena asphodeloides.

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