Ultrasensitive LC-MS/MS quantitation of the N-nitroso-dabigatran etexilate impurity in dabigatran etexilate mesylate using an electrospray ionization technique†

Nitrosamine impurities, particularly nitrosamine drug substance-related impurities (NDSRIs), pose significant health risks due to their potential mutagenicity and carcinogenicity. Consequently, stringent regulatory guidelines have been established for their detection and quantification in pharmaceutical products. This study presents a simple, robust, and ultrasensitive liquid chromatography-tandem mass spectrometry (LC-MS/MS) method to quantify the N-nitroso-dabigatran etexilate (NDE) impurity in the drugs and capsules of dabigatran etexilate (DEM) using an electrospray ionization technique. Using a gradient elution program, with mobile phase A consisting of 5 mM ammonium formate buffer (pH 7.0 ± 0.1) and mobile phase B 100% acetonitrile, chromatographic separation was achieved on a Sapphirus C18 HP-classic column (250 mm × 4.6 mm × 5 μm). The system utilized an Agilent 1290 infinity series LC with a 6470B LC/TQ tandem mass spectrometer, operating at a 0.6 mL min⁻¹ column flow rate. Detection and quantitation of the N-nitroso dabigatran etexilate (NDE) impurity were performed in positive ESI mode using multi-reaction monitoring (MRM). The validation of the method adhered to the ICH Q2 (R2) guidelines, showing excellent signal-to-noise ratios for the detection and quantification limits, with linearity observed (correlation coefficient > 0.99) over a range of 18–120 ppb. Accuracy was confirmed through recovery studies, yielding satisfactory results between 80 and 120% of spiked concentrations. This validated LC-MS/MS method is suitable for routine and stability analysis of N-nitroso-dabigatran etexilate (NDE) impurities in both drug substance and finished capsules.