Characterization and relative response factor determination of process related impurity in Naproxen by nuclear magnetic resonance spectroscopy.

In the impurity profile of naproxen around 0.6% unknown polar impurity was detected by high performance liquid chromatography (HPLC). The product ion spectrum of the impurity and Naproxen was recorded in LCMS/MS and the fragmentation pattern of the impurity was observed to be similar to the fragmentation pattern of Naproxen with only a difference of two atomic mass units.