Filiz Demir, Sıdıka Ertürk Toker
The primary objective of this study was to develop and validate a liquid chromatography-atmospheric pressure chemical ionization-tandem mass spectrometric (LC-APCI-MS/MS) method for the determination of trace levels of N-nitroso vonoprazan (NVNP) in vonoprazan active pharmaceutical ingredient (API) and pharmaceutical products. Chromatographic separation was achieved on an Acquity® Premier HSS T3 column under isocratic conditions using 0.1% formic acid in water and acetonitrile as the mobile phase. Detection was performed in positive ion mode using multiple reaction monitoring. The method was validated according to ICH Q2(R2) guidelines for selectivity, linearity, accuracy, precision, robustness, matrix effect, limit of detection (LOD), and limit of quantification (LOQ). The method was linear over the concentration range of 0.24-50.0 ng/mL (R2 = 0.9971), with recoveries of 85.6%-99.2% and relative standard deviation values below 6.1%. The validated LOD and LOQ were 0.10 and 0.24 ng/mL, respectively; the latter corresponds to 0.24 μg/g (240 ppb) in the pharmaceutical product. Matrix effect evaluation showed 91.6% response (8.4% ion suppression), indicating minimal matrix interference. The validated LC-APCI-MS/MS method was successfully applied to both API and finished products and is suitable for routine quality control, stability studies, nitrosamine risk assessment, and regulatory monitoring of NVNP.