Enantiomeric LC separation of valsartan on amylose based stationary phase.

A simple, rapid and robust LC method was developed and validated for the enantiomeric separation of valsartan in bulk drug and formulation. The enantiomers of valsartan were resolved on a Chiralpak AD-H (amylose based stationary phase) column using a mobile phase consisting of n-hexane: 2-propanol: trifluoroacetic acid (85:15:0.2, v/v/v) at a flow rate of 1.0 mL/min. The resolution between the enantiomers was found to be not less than 3.2. The presence of trifluoroacetic acid in the mobile phase played an important role in enhancing chromatographic efficiency and resolution between the enantiomers. The calibration curve for the (R)-enantiomer showed excellent linearity over the concentration range of 600 ng/mL (LOQ) to 6000 ng/mL. The limit of detection and limit of quantification for the (R)-enantiomer were 200 and 600 ng/mL, respectively. The percentage recovery of the (R)-enantiomer ranged between 98.7 to 100.05 % in bulk drug samples of valsartan. The proposed method was found to be suitable and accurate for quantitative determination of (R)-enantiomer in bulk drug substance.