Preparation of a thiols ß-cyclodextrin/gold nanoparticles-coated open tubular column for capillary electrochromatography enantioseparations.

Inspired by the distinct chemical and physical properties of nanoparticles, here a novel open-tubular capillary electrochromatography column was prepared by electrostatic assembly of poly(diallydimethylammonium chloride) onto the inner surface of a fused-silica capillary, followed by self-adsorption of negatively charged SH-ß-cyclodextrin/gold nanoparticles. The formation of the SH-ß-cyclodextrin/gold nanoparticles coated capillary was confirmed and characterized by scanning electron microscopy and energy dispersive spectrometry. The results of scanning electron microscopy and energy dispersive spectrometry studies indicated that SH-ß-cyclodextrin/gold nanoparticles were successfully coated on the inner wall of the capillary column. The performance of the SH-ß-cyclodextrin/gold nanoparticles coated capillary was validated by the analysis of six pairs of chiral drugs, namely zopiclone, carvedilol, salbutamol, terbutaline sulfate, phenoxybenzamine hydrochloride, and ibuprofen. Satisfactory enantioseparation results were achieved, confirming the use of gold nanoparticles as the support could enhance the phase ratio of the open-tubular capillary column. Additionally, the stability and reproducibility of the SH-ß-cyclodextrin/gold nanoparticles coated capillary column were also investigated. Then, this proposed method was well validated with good linearity (≥0.999), recovery (90.0-93.5%) and repeatability, and was successfully used for enantioseparation of ibuprofen in spiked plasma samples, which indicated the new column's potential usage in biological analysis.

Box-Behnken response surface modeling assisted enantiomeric resolution of some racemic ß-blockers using HPTLC and ß-cyclodextrin as chiral mobile phase additive: Application to check the enantiomeric purity of betaxolol.

Stereospecific separation method of (±) betaxolol, (±) carvedilol, and (±) sotalol using High Performance Thin Layer Chromatography (HPTLC) and ß-cyclodextrin as chiral selector has been developed and validated. The Box-Behnken surface response design was selected for optimizing the operating variables based on 15 trials design. The optimized method involves separation on Fluka HPTLC silica gel plates 60 F254 (20 × 10 cm) using acetonitrile-methanol-acetic acid-water (3.4:3.6:0.18:1 v/v) as a mobile phase containing 0.57 mM ß-cyclodextrin. Densitometric measurements were made at 220 nm for betaxolol and sotalol or at 245 nm for carvedilol. Maximum separation of the enantiomers of the three drugs was obtained by optimizing concentration of chiral selector, the mobile phase composition including acetonitrile amount in the organic part of the mobile phase and the volume of acetic acid added. The proposed method enables estimation of (-) and (+) enantiomers of betaxolol in drug substance and in various pharmaceuticals. The detection limit of betaxolol was 0.15 and 0.13 µg band-1 for (-) and (+) enantiomers, respectively. The detection limits were found to be 0.2 and 0.3 µg band-1 for carvedilol and sotalol, respectively, as racemate. In addition, the proposed method was applied in checking the enantiomeric purity of (-) BET in the presence of (+) BET at 1% level where the inactive (+) enantiomer was quantified with good accuracy and precision at 1% level in the active (-) enantiomer.