Search

The present work narrates an LC method for determination of enantiomeric purity of (4 S,5 R)-3,5-oxazolidinedicarboxylic acid 2,2-dimethyl-4-phenyl-3-(1,1-dimethylethyl) ester, which is a key starting material of docetaxel, an antineoplastic agent and belongs to the taxoid family. Resolution between enantiomers was achieved ≥4.0 within 30 min on Chiralpak AD-H (250 mm × 4.6 mm) column using n-hexane, 2-propanol, ethanol and trifluoroacetic acid (97.5, 1.5, 1.0, 0.15 v/v) as mobile phase at a flow rate of 1.0 mL min−1 at 25 °C. The detection was made at 215 nm using UV detection. The effects of 2-propanol, ethanol and temperature on enantioselectivity and resolution of enantiomers were evaluated. The method was validated for (4 R,5 S)-enantiomeric impurity in terms of accuracy, precision and linearity in the range of 0.5–5 μg mL−1 and the correlation coefficient was >0.999. The recoveries were 93.2–104.4%. The limits of detection (LOD) and quantification (LOQ) of unwanted (4 R,5 S)-enantiomer was 0.1 and 0.5 μg mL−1. The method was found to be suitable for rapid quantification of (4 R,5 S)-enantiomer of docetaxel starting material. [ABSTRACT FROM AUTHOR]

A new stereospecific LC method for the separation and quantification of moxifloxacin and its ( R, R)-enantiomer in bulk drug was developed and validated by ligand-exchange liquid chromatography on a reversed phase column using aqueous mobile phase containing the chiral reagent l-isoleucine-Cu(II). The UV detector was operated at 293 nm. The flow rate of mobile phase was set at 0.9 mL min−1. The achiral ODS column offers good separation of the two enantiomers in less than 20 min. The test concentration was 1,000 μg mL−1 in the mobile phase. This method was capable of detecting the ( R, R)-enantiomer of moxifloxacin up to 0.1 μg mL−1 for a 20 μL injection volume. The drug was subjected to stress conditions of hydrolysis, oxidation, photolysis and thermal degradation. There was no interference of degradants with the ( R,R)-enantiomer in the developed method. The developed chiral RP-LC method was validated with respect to linearity, accuracy, precision and robustness. The percentage recovery for the ( R, R)-enantiomer in bulk drug samples ranged from 98.1 to 104.4%. The test solution was found to be stable in the mobile phase for 48 h after preparation. [ABSTRACT FROM AUTHOR]

A simple, inexpensive and rapid isocratic LC method has been developed for the quantative determination of Rimonabant, an anti-obesity drug. The method can also be employed for the determination of Rimonabant and its impurities in the bulk drug. Degradation studies were performed on the bulk drug by heating to 60 °C, exposure to UV light at 254 nm, acid (0.5 N hydrochloric acid), base (0.5 N sodium hydroxide) and aqueous hydrolysis and oxidation with 3.0% v/v hydrogen peroxide. Considerable degradation was observed under oxidation conditions. Good resolution between the peaks corresponding to impurities produced during synthesis, degradation products and the analyte was achieved on a Phenomenex Gemini C18 LC column using a mobile phase consisting of a mixture of aqueous potassium dihydrogen phosphate (pH 3.0) and acetonitrile. The degradation samples were assayed against the reference standard of Rimonabant and the mass balance in each case was close to 99.5%. Validation of the method was carried out as per ICH requirements. [ABSTRACT FROM AUTHOR]