Determination and Quantification of an N-Nitroso Desmethyl Olopatadine in the Olopatadine Hydrochloride Active Pharmaceutical Ingredient by LC-MS/MS

A Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS) method was developed for the quantification of N-Nitroso Desmethyl Olopatadine in the Olopatadine Hydrochloride active pharmaceutical ingredient. Chromatographic separation was achieved using a phenyl hexyl column, with 2 mm ammonium formate in water and acetonitrile as mobile phase in gradient elution mode at a 0.5 ml/ min flow rate. Quantification was carried out using triple quadrupole mass detection with electrospray ionization in the multiple reaction monitoring modes. The method was validated with good linearity over the concentration range of 0.014 ppm-0.210 ppm. The correlation coefficient obtained in each case was >0.9990. The recoveries were found to be satisfactory over the range between 80.0 and 120.0% for N-Nitroso Desmethyl Olopatadine. The developed method was able to quantitate N-Nitroso Desmethyl Olopatadine at a concentration level of 0.14 ppm with respect to 0.5 mg mL-1 Olopatadine Hydrochloride