Determination of nitrite in rifapentine and analysis of the formation causes of nitrosamine impurity

Introduction During drug manufacturing, residual nitrosamine salts in the final formulation are a key contributor to the formation of genotoxic nitrosamine impurities. However, trace-level concentrations and strong matrix interference complicate nitrosamine salt detection; therefore, selecting an appropriate analytical method is crucial. Methods We developed a valve-switching ion chromatography method and performed method validation. We also conducted nitrification degradation experiments and validation studies of the nitrification pathway by detecting 14 N-CPNP and 15 N-CPNP using LC-HRMS after adding 15 N-nitrite to rifaentine. Results and Discussion The results of the method validation indicate its good linearity, accuracy, quantification, and detection limits. Nitrification degradation experiments demonstrate that CPNP in rifapentine can be generated via a nitrosation pathway. This pathway has also been validated by experimental results. This IC analytical method has the dual applications of genotoxic impurity quality control and elucidating impurity formation pathways in small-molecule drugs.