Determination of Nitrosamine impurities in Losartan Potassium drug substance using Triple Quadrupole Liquid Chromatography Mass Spectrometry

Importance of the Topic

Losartan Potassium and related angiotensin receptor blockers have been subject to global recalls due to trace levels of nitrosamine impurities. These compounds are classified as probable carcinogens and are tightly regulated by agencies such as FDA and EMA. Sensitive and reliable detection of nitrosamines is essential to ensure drug safety and compliance with regulatory limits.

Objectives and Overview

This study aimed to develop and validate a rapid liquid chromatography–tandem mass spectrometry method using a triple quadrupole instrument for the quantification of six nitrosamines (NDMA, NDEA, NMBA, NEIPA, NDIPA, NDBA) in Losartan Potassium drug substance at sub-parts-per-billion levels. The goal was to achieve robust performance suitable for routine quality control and regulatory monitoring.

Methodology

Sample preparation involved weighing 100 mg of Losartan Potassium, extracting with a methanol–water diluent, vortex mixing, shaking, centrifugation and filtration to remove particulates. Chromatographic separation was performed on a phenyl-hexyl column with gradient elution of 0.2% formic acid in water and methanol. Dynamic multiple reaction monitoring with atmospheric pressure chemical ionization in positive mode was optimized for each nitrosamine, yielding low background and high signal.

Instrumentation

• Agilent 1290 Infinity II LC system (pump, multisampler, column thermostat)
• Agilent 6470 triple quadrupole mass spectrometer with APCI source
• Zorbax Eclipse Plus Phenyl-Hexyl RRHD column 2.1×100 mm, 1.8 μm

Main Results and Discussion

The method exhibited excellent linearity across calibration ranges (r2 > 0.997) down to 0.05 ng/mL for NDMA, NMBA, NDEA and 0.1 ng/mL for the remaining analytes. Intermediate precision studies at the limit of quantification demonstrated area RSDs below 6%. Recovery experiments at spiked levels yielded recoveries between 91% and 113%, confirming accuracy. The chromatographic configuration allowed diversion of the high-concentration Losartan peak away from the MS detector, preventing source contamination.

Benefits and Practical Applications

The validated method provides high sensitivity, reproducibility and throughput for routine screening of nitrosamine impurities in supporting regulatory submissions and quality control testing of Losartan Potassium batches. Direct analysis with minimal sample handling enhances laboratory efficiency and data reliability.

Future Trends and Opportunities

Advances in high-resolution accurate mass spectrometry may further improve selectivity and reduce false positives. Integration with automation platforms and on-line sample cleanup can increase throughput. Continuous method refinement will be driven by evolving regulatory guidelines and emerging nitrosamine targets in pharmaceuticals.

Conclusion

A robust LC–MS/MS method using a triple quadrupole instrument was developed for trace-level quantification of six nitrosamine impurities in Losartan Potassium. The approach meets stringent regulatory requirements with excellent sensitivity, precision and accuracy and is well suited for routine QC and regulatory testing.

References

• Agilent Technologies, Inc. Poster Reprint ASMS 2020, WP 555.