ANALYTICAL DEVELOPMENT AND VALIDATION OF A LC-MS METHOD FOR ESTIMATION OF N-NITROSO DICLOFENAC IN DICLOFENAC SODIUM GEL 3%

A new liquid chromatography-mass spectrometry (LC-MS) method that is selective and sensitive was developed and validated for the identification and quantification of N-Nitroso Diclofenac Impurity in Diclofenac Sodium Gel by LC-MS. The method is specific, accurate and precise. Chromatographic separation was accomplished on a symmetry C18 column 250x4.6mm, 5µ, using gradient type of separation. In which two different composition of mobile phase were used i.e. Mobile Phase A is a mixture of buffer (ammonium formate and formic acid) and acetonitrile (75:25) whereas Mobile Phase B is Acetonitrile (100%) with run time of 35 minutes. Linearity range of 0.000048 to 0.010055 µg/mL and 0.06 to 12.57 µg/mL (concentration with respect to sample). The standard solution of N-Nitroso Diclofenac is stable up to 44 hours and sample solution of Diclofenac Sodium Gel 3% is stable for 35 minutes. The method is validated according to ICH Q2 (R1).