A Comprehensive Approach for the Determination and Quantification of N-Nitroso Desmethyl Olopatadine in the Olopatadine Hydrochloride Ophthalmic Solution by RPHPLC

A High-performance liquid chromatography (HPLC) method was developed to quantify N-Nitroso Desmethyl Olopatadine impurity in an olopatadine hydrochloride ophthalmic solution. Chromatographic separation was achieved using a Poroshell 120l Phenyl Hexyl (150 × 4.6 mm, 2.7 µ) column with Mobile phase-A (1.36 g/L Potassium hydrogen phosphate pH-3.0): Acetonitrile (95:5 v/v) and mobile phase-B (Acetonitrile: water, 98:2 v/v) in gradient elution mode at a 0.8 mL/min flow rate. Quantification was performed using PDA/UV-visible detection; the method was validated with good linearity over the concentration range of 0.27 ppm-4.05 ppm. The correlation coefficient obtained in each case was >0.99. The recoveries were found to be satisfactory at the level of LOQ over the range between 70.0% to 130.0% and for the other levels between 80 %-120 % for N-nitroso desmethyl olopatadine. The developed method was able to quantitate N-nitroso desmethyl olopatadine at a concentration level of 0.27 ppm for 400 ppm olopatadine hydrochloride.