An Enhanced and Highly Sensitive LC–MS‐Based Analytical Approach for the Quantitative Determination of Carcinogenic N‐Nitrosopiperazine in Cetirizine Dihydrochloride

Nitrosamine impurities, which are categorized as mutagenic and probable human carcinogens, have been widely detected in various drug substances and products. This study investigates the formation of the N-nitrosopiperazine (NNPZ) genotoxic impurity during the manufacturing of cetirizine dihydrochloride (CTZ), originating from piperazine, a key starting material. A sensitive and selective LC-MS method was developed for the accurate quantification of NNPZ in the CTZ drug substance. The allowable intake limit for NNPZ is 26.5ng/day and maximum daily dose 880mg/day as per US FDA. This analytical method was developed and validated in accordance with ICH Q2R2 guidelines. It demonstrated a low detection limit (LOD) of 0.03 ng/mL and a quantitation limit (LOQ) of 0.1 ng/mL. The linearity study yielded a strong regression coefficient of 0.9974. With a high recovery rate of 96.56% to 102.35% for spiked NNPZ, the method's accuracy was well-established. The overall results confirm that this methodology is reliable, precise, and reproducible, and it can therefore be used for the determination of NNPZ-genotoxic impurity in CTZ drug substance samples via LC-MS.