Highly‐Sensitive Liquid Chromatography Triple Quadrupole Mass Spectrometry Method for the Ultra‐Trace Quantification of N‐Nitrosamine Impurity in Opipramol Drug Substance and Tablet Formulations

ABSTRACT

Regulatory bodies require strict control of N‐nitrosamine drug substance‐related impurities due to their possible carcinogenic risk. In this work, a quick and highly sensitive liquid chromatography coupled triple quadrupole mass spectrometry method was established for the trace‐level quantification of the nitrosamine impurity‐2‐(4‐nitrosopiperazin‐1‐yl)ethanol (N‐NPE) in the tricyclic antidepressant Opipramol drug substance and its tablet formulations. As derived from the carcinogenicity potency categorization approach, N‐NPE is classified as Category 3, with an endurable intake limit of 400 ng/day. Chromatographic separation was achieved on a Waters C18 column (150 mm × 2.1 mm, 1.8 µm) using 0.1% formic acid and acetonitrile under gradient mode of elution with a mobile phase delivery rate of 0.3 mL/min. Detection stood executed using triple quadrupole mass spectrometry with electrospray ionization in multiple reaction monitoring mode, employing transitions m/z 160.08→130.11(quantifier) and 160.08→112.03 (qualifier). Successfully confirmed the method's performance parameters as per the ICH guidelines and proven admirable sensitivity, specificity, and robustness. This method works well for routine quality control of N‐NPE, ensuring regulatory compliance through sensitive and reliable trace‐level quantification. By effectively controlling this potentially genotoxic impurity, it supports patient safety and enhances the overall quality of OPM pharmaceutical products.