Determination of related substances of travoprost in travoprost and timolol maleate eye drops by HPLC

[Objective:] To develop a high-performance liquid chromatography (HPLC) method for the determination of related substances in Travoprost and Timolol Maleate Eye Drops, sepcifically focusing on Travoprost and its impurities. [Methods:] The analytic column used was an Agilent SB-C18 (50 mm × 2.1 mm, 2.7 μm) . A phosphoric acid solution (prepared by diluting 2.0 mL of phosphoric acid with wateto final volume of 1 000 mL and adjust the pH to 3.0 with sodium hydroxide solution) was used as mobile phase A, while acetonitrile served as mobile phase B. The elution was performed using a gradient program at a flow rate of 3.0 mL/min. The detection wavelength was set at 220 nm, and the column temperature was maintained at 30℃. The injection volume is 100 μL. [Results:] Under the described chromatographic condition, Travoprost and its various impurities were well separated. The purity of the Travoprost peak was qualified, and the material remained stable under conditions of acid, alkali, oxidation, high temperature, and strong light exposure. The linear ranges for Travoprost, 5,6-trans-Travoprost, and 15-keto-Travoprost were determined to be 0.041-3.245 μg/mL(r=1.000 0), 0.040~3.229 μg/mL(r=1.000 0), 0.039~3.088 μg/mL(r=0.999 9), respectively. The lowest detection limits for these compounds were all 0.020 μg/mL, The relative standard deviation (RSD) for the content of 5,6-trans-travoprost and 15 keto trovopros in six samples were 0.2% (n=6) and 0.3% (n=6), respectively, indicating good reproducibility. Both the reference solution and the test solution remained stable at room temperature for 100 hours,The average recovery rates for 5,6-trans-Travoprost and 15-keto-Travoprost were 95.2% (RSD 0.5%, n=9) and 92.7% (RSD 1.2%, n=9).respectively, further confirming the high reproducibility of the method. [Conclusions:] The developed HPLC method is simple, rapid, and accurate, making it suitable for the determination of related substances in Travoprost and Timolol Maleate Eye Drops.