Duloxetine EP Impurity G

Duloxetine EP Impurity G is a fluoro-substituted aromatic hydrocarbon derived from the synthetic pathway of duloxetine. Its structure features a naphthalene core bearing a single fluorine substituent at the 1-position, conferring distinct electronic and steric properties compared to the parent drug. This impurity arises as a byproduct during coupling reactions involving fluorinated intermediates, where incomplete substitution or side-chain elimination occurs. The compound exhibits a rigid, planar aromatic system with a low-degree of hydrogenation, contrasting with duloxetine’s cyclohexyl moiety. It serves as a critical HPLC reference standard for quantifying process-related impurities in duloxetine formulations.