Highly Sensitive and Robust UPLC-MS/MS Quantification of Nitrosamine Impurities in Sartan and Ranitidine Drug Substances

Significance of the Topic

Ensuring the safety and efficacy of pharmaceutical products requires accurate monitoring of genotoxic N-nitroso impurities, such as NDMA, NDEA, NDBA, and NDIPA. Regulatory agencies impose strict limits (0.3 and 0.03 ppm) to control carcinogenic risk. The structural diversity and poor chromatographic retention of these compounds make simultaneous quantification challenging, driving demand for sensitive and robust analytical techniques.

Objectives and Overview of the Study

This work aimed to develop a rapid UPLC-MS/MS method capable of detecting and quantifying multiple nitrosamine impurities at sub-ppb levels in sartan APIs and ranitidine drug products. Emphasis was placed on enhancing ionization efficiency and chromatographic separation to achieve low limits of detection and quantification.

Methodology

An Acquity UPLC HSS T3 column (2.1 × 100 mm, 1.6 µm) was used with a water–methanol gradient containing 0.1% formic acid and 5 mM ammonium formate. Total run time was 7 minutes. Ionization was compared between ESI and the IonSABRE APCI probe, with multiple reaction monitoring (MRM) transitions optimized for each nitrosamine. LODs and LLOQs were established by spiking standards into neat solvent and drug product matrices.

Used Instrumentation

• Waters ACQUITY I-Class PLUS UPLC system
• ACQUITY UPLC HSS T3 column (2.1 × 100 mm, 1.6 µm)
• Waters Xevo TQ-XS tandem quadrupole mass spectrometer
• IonSABRE APCI probe and ESI probe

Main Results and Discussion

• The IonSABRE APCI source delivered approximately 10× higher sensitivity for NDMA compared to ESI, improving analyte response and signal-to-noise.
• Chromatographic separation resolved all target nitrosamines in under 7 minutes with baseline baseline resolution.
• LLOQs ranged from 0.025 to 0.10 ng/mL across different nitrosamine compounds, meeting stringent regulatory thresholds.
• Endogenous NDMA (~29 ng/mL) was detected in ranitidine drug product, while blank formulations showed no detectable GTIs.
• Use of a divert valve minimized matrix effects by directing API to waste outside the MS acquisition window, enhancing robustness.

Benefits and Practical Applications

The described UPLC-MS/MS method offers rapid throughput, excellent sensitivity and selectivity, and compatibility with routine quality control workflows. It enables pharmaceutical manufacturers and regulatory laboratories to reliably screen for genotoxic nitrosamine impurities in both drug substances and finished products.

Future Trends and Opportunities

Advances in ion source design, high-resolution mass spectrometry, and automated sample preparation are expected to further improve detection limits and streamline workflows. Expanding the method to cover emerging nitrosamines and diverse drug matrices, along with application of greener solvents and on-line cleanup techniques, will enhance sustainability and applicability across the industry.

Conclusion

A sensitive and robust UPLC-MS/MS approach using IonSABRE APCI detection was successfully developed for quantifying multiple nitrosamine impurities at sub-ppb levels in sartan and ranitidine products. The method meets current regulatory requirements and supports reliable monitoring of genotoxic impurities in pharmaceutical development and manufacturing.

References

• Trudeau Lame M., Hatch L., Higton D., Rainville P., Fujimoto G. Highly Sensitive and Robust UPLC-MS/MS Quantification of Nitrosamine Impurities in Sartan and Ranitidine Drug Substances. Waters Corporation, Milford, MA, USA, 2020.