Enantiomeric separation of drugs and herbicides on a beta-cyclodextrin-bonded stationary phase

Preparation and enantioseparation characteristics of three chiral stationary phases based on modified beta-cyclodextrin for liquid chromatography

In order to study the effect of the nature and the length of the spacer, three mixed 10-undecenoate/phenylcarbamate derivatives of beta-cyclodextrin have been prepared and linked to allylsilica gel by means of a radical reaction. The chiral recognition ability of the resulting materials, when used as liquid chromatography chiral stationary phases (CSPs), was evaluated using heptane and either 2-propanol or chloroform as organic mobile-phase modifiers. A large variety of racemic compounds have been separated successfully on these CSPs (mainly pharmaceuticals and herbicides). Optimization of these separations was discussed in terms of mobile-phase composition and structural patterns of the injected analytes. The efficiencies of the three prepared materials were compared to those of previously described perphenylated-beta-cyclodextrin column and to analogous cellulose derivative-based CSPs.

Preparation and chromatographic properties of a multimodal chiral stationary phase based on phenyl-carbamate-propyl-beta-CD for HPLC

A phenylcarbamate derivative of 2-hydroxypropyl-beta-CD bonded stationary phase was prepared by a previously described method. Its enantiomeric recognition abilities were evaluated as chiral stationary phase (CSP) in normal, polar organic and RP conditions by HPLC. The relevant structural features of the prepared stationary phase which make it an effective chiral selector are discussed. This material seems to have an excellent enantioselectivity for a variety of racemic analytes in the three modes. Hence it can be considered a highly effective multimodal column. Retention factor (k), selectivity (alpha) and resolution (R(s)) were the chosen parameters to describe the column performance. Optimization of these separations was discussed in terms of mobile phase composition, flow rate and structural patterns of the injected analytes.

Spectrophotometric determination of propranolol in formulations via oxidative coupling with 3-methylbenzothiazoline-2-one hydrazone

A simple spectrophotometric method has been developed for the determination of propranolol hydrochloride in pure as well as in dosage forms. The method is based on the oxidative coupling reaction with 3-methylbenzothiazoline-2-one hydrazone. A mixture of an acidic solution of the chromogenic agent and the drug upon treatment with ceric ammonium sulfate produces an orange color peaking at 496 nm. The absorbance-calibration plot was linear over the range 1-10 microg/ml with minimum detectability (S/N=2) of 0.1 microg/ml (3.38x10(-7) M). The molar absorbitivity was 3.195x10(3) l/M/cm with correlation coefficient (n=10) of 0.9999. The different experimental parameters affecting the development and stability of the color were carefully studied and optimized. The proposed method was applied successfully to the determination of propranolol in its dosage forms. A proposal of the reaction pathway was presented.