Quantitation of 8 Nitrosamines in 12 different solvents by LC-MS/MS system

Significance of the Topic

The reliable quantification of nitrosamine impurities in solvents is critical for pharmaceutical quality control and regulatory compliance. Recent recalls due to N-nitrosodimethylamine (NDMA) contamination highlight the need for robust analytical methods capable of detecting multiple nitrosamines at sub-ppm levels across diverse solvent matrices.

Objectives and Study Overview

This study aimed to develop and validate a single liquid chromatography–tandem mass spectrometry (LC-MS/MS) method for the simultaneous determination of eight nitrosamines in twelve commonly used solvents. Key goals included achieving regulatory limits (0.03 ppm), accommodating solvents with varying polarity and boiling points, and demonstrating method extension potential.

Methodology and Instrumentation

• Instrumentation: Shimadzu Nexera XSi UHPLC coupled to LCMS-8045 triple quadrupole MS with APCI interface.
• Column: Shim-pack™ GIST C18-AQ, 100 × 4.6 mm, 3 µm, 40 °C.
• Mobile phase: 0.1% formic acid in water (A) and methanol (B) at 0.7 mL/min with a stepped gradient.
• Detection: Multiple reaction monitoring (MRM) transitions optimized for each nitrosamine and deuterated internal standard.

Sample Preparation Strategies

• Direct injection for polar solvents (water, methanol, ethanol, acetonitrile, isopropanol, DMSO).
• Evaporation-reconstitution for volatile solvents (dichloromethane, acetone, chloroform, ethyl acetate) to enhance sensitivity.
• Dilution in methanol for non-polar solvents (toluene, DMF) to improve peak shape.

Key Results and Discussion

• Calibration: Linear response from 0.001 to 0.100 ppm (R² > 0.993 for all analytes).
• Limits of quantitation (LOQs) ranged from 0.001 to 0.010 ppm, meeting the 0.03 ppm requirement in all solvents.
• Recoveries at LOQ levels were generally between 90% and 115%, demonstrating method accuracy across matrices.
• DMSO required matrix-matched calibration due to enhanced sensitivity for certain nitrosamines.
• DMF interfered with NDMA detection, warranting GC-MS as a complementary technique for that analyte.

Benefits and Practical Applications of the Method

This unified LC-MS/MS approach delivers rapid, sensitive and accurate quantitation of eight nitrosamines in multiple solvents. It streamlines quality control workflows in pharmaceutical manufacturing and supports compliance with evolving regulatory standards.

Future Trends and Potential Applications

• Extension to additional nitrosamine species and alternative solvents or excipients.
• Integration into automated sampling and data processing platforms for high-throughput screening.
• Application in environmental monitoring of water and food matrices.
• Advancements in ambient ionization for rapid on-site testing.

Conclusion

The developed LC-MS/MS method on the Shimadzu LCMS-8045 system provides a robust, sensitive, and versatile platform for nitrosamine analysis in diverse solvent matrices. It fulfills current regulatory requirements and can be adapted for broader analytical applications.

References

• Rane S., Tupe D., Bhandarkar D., Kelkar J., Rasam P. Quantitation of 8 nitrosamines in 12 different solvents by LC-MS/MS system. Shimadzu Analytical (India) Pvt. Ltd., Application News, 2021.
• FDA. Investigation of nitrosamine impurities in ARB drug products; 2018.