RP-HPLC determination of two stereoisomers in latanoprost eye drop

To establish an HPLC method for the determination of impurity I and impurity II in latanoprost eye drop. HPLC separation was carried on a Zorbax SB- C₁₈ column(4. 6 mm250 mm, 5 m)with the mobile phase consisting of methanol-acetonitrile-water(adjusting pH to 3. 0 with acetic acid)(56 ∶14 ∶30). The flow rate was 1. 0 mL/min; the detection wavelength was 210 nm; and the injection volume was 100 μL. Impurity I, impurity II and latanoprost were separated efficiently under the selected HPLC conditions, with good linearity in the range of 0. 049 99-0. 999 8 g/mL for impurity I and 0. 049 94-0. 998 8 g/mL for impurity II. The average recoveries of impurity I and II were 96. 74%(n=9)and 94. 99%(n=9), respectively. The established method can be used for the detection of stereoisomers in latanoprost eye drop.