Cetirizine Impurity-F

Cetirizine Impurity-F is a structurally related degradation byproduct arising from oxidative cleavage of the piperazine ring in the parent antihistamine Cetirizine. It retains the core 2-(2-(4-(4-chlorophenyl)-1-piperazinyl)ethyl)propane-1,3-diol scaffold but features an additional methoxy group at the C-3 position of the propane backbone, coupled with a dechlorinated aromatic ring. This impurity exhibits a distinct UV absorption maximum at 248 nm due to conjugated aromatic systems and is characterized by a tertiary amine piperazine moiety. Its primary application is as a reference standard for HPLC-based impurity profiling in Cetirizine drug substance stability studies.