A Validated Lc Method for Determination of the Enantiomeric Purity of Atorvastatin in Bulk Drug and Dosage Forms

A simple, rapid isocratic chiral HPLC method has been developed for the separation of (S, S)-Atorvastatin from (R, R)-Atorvastatin and quantitative determination of (S, S)-Atorvastatin enantiomer in bulk drug and pharmaceutical dosage forms. Normal phase chromatographic separation was achieved on chiral stationary phase, Chiral pak AD-H (250 mm × 4.6 mm ID) column at 30°C temperature. Flow rate was kept at 1.0 mLmin. The elution time was ~ 8.0 min and the resolution (Rs) between the enantiomers is greater than 2.5. Interestingly (S, S) form of Atorvastatin peak was eluted prior to the (R, R) form of Atorvastatin. The limit of detection (LOD) and limit of quantification (LOQ) for the (S, S) Atorvastatin were 0.18μg mL and 0.60μg mL respectively, for a 10μL load of the sample. The method was validated in terms of linearity, precision and accuracy and satisfactory results were obtained. Robustness studies were also performed. The sample solution stability of Atorvastatin was determined and the compound was found to be stable up to 48 h.