A Robust and Sensitive Instrument for Quantification of N-Nitroso labetalol impurity in Labetalol Drug Product

Importance of the Topic

Ensuring the safety of drug products by monitoring nitrosamine impurities is critical due to their potential health risks. Regulatory bodies like USP-NF highlight the necessity to control nitrosamine drug substance-related impurities (NDSRIs) throughout the drug lifecycle.

Objectives and Study Overview

This study aims to develop a robust and sensitive analytical method for quantifying N-nitroso labetalol impurity in labetalol formulations. The research addresses matrix effects and low-level detection challenges, ensuring compliance with regulatory limits.

Methodology and Used Instrumentation

To achieve accurate quantification, samples undergo a tailored extraction procedure to reduce matrix interference and enhance spiked recovery. Chromatographic separation uses an Acquity UPLC BEH C18 column coupled with Waters Xevo TQ-S Cronos mass spectrometer operating in RADAR acquisition mode, which integrates multiple reaction monitoring (MRM) and full-scan MS.

Main Results and Discussion

• The method exhibited a linear response from 0.003 to 1.5 ppm for N-nitroso labetalol.
• Method limit of quantification (LOQ) was 0.03 ppm, with instrument LOQ at 0.003 ppm.
• Signal-to-noise ratios exceeded 300 at 0.003 ppm relative to the API.
• Spiked recovery ranged between 70% and 120%, with an average of 93.5%.
• RADAR scans demonstrated clear separation between the API and NDSRI, enhancing method robustness by diverting the API peak.

Benefits and Practical Applications of the Method

This approach provides pharmaceutical manufacturers with a reliable tool for routine quality control of labetalol products. Rapid detection of trace nitrosamine impurities supports risk mitigation and regulatory compliance, contributing to patient safety.

Future Trends and Potential Applications

Emerging trends include high-throughput screening using advanced RADAR acquisition strategies and integration with automated sample preparation platforms. Extending this methodology to other nitrosamine impurities can streamline impurity profiling across diverse drug formulations.

Conclusion

The combination of tailored sample preparation, UPLC separation, and Xevo TQ-S Cronos RADAR mass spectrometry offers a sensitive and robust solution for quantifying N-nitroso labetalol impurities. This method aligns with regulatory expectations and enhances control of critical safety-related impurities.

Used Instrumentation

• Waters Xevo TQ-S Cronos triple quadrupole mass spectrometer
• Waters Acquity UPLC H-Class Plus system
• Waters Acquity UPLC BEH C18 column