Overcoming the challenges of nitrosamine impurities in drugs

Significance of the topic

Nitrosamine impurities in pharmaceuticals pose serious health risks due to their classification as probable human carcinogens by IARC and mutagenic Class 1 impurities under ICH M7. Regulatory agencies require manufacturers to control levels of NDMA, NDEA and related nitrosamines below strict limits (e.g., <0.03 ppm in drug substances) and to implement analytical strategies that ensure patient safety and regulatory compliance.

Goals and overview of the study

This case study reviews advanced GC-MS solutions for cGMP-compliant nitrosamine testing in active pharmaceutical ingredients (APIs) and finished dosage forms. It compares static headspace GC-MS, GC-MS/MS with direct injection, and high-resolution Orbitrap GC-MS to demonstrate sensitivity, selectivity and robustness in trace-level nitrosamine quantification and screening.

Used methodology and instrumentation

The study evaluates:

• Static headspace GC-MS (Thermo Scientific TriPlus 500 HS + ISQ 7000 single quadrupole) for NDMA/NDEA (LOD 0.004–0.009 ppm, LOQ 0.015–0.030 ppm).
• Direct liquid-injection GC-MS/MS (TSQ 9000 triple quadrupole) in SRM mode for six volatile nitrosamines with LODs <0.0005 ppm and high repeatability (%RSD <8).
• Enhanced ionization (AEI) on TSQ 9000 for further improved sensitivity (S/N >7 at 0.5 ng/mL).
• Full-scan and SIM high-resolution Orbitrap GC-MS (Exactive GC-Orbitrap) for combined targeted quantification and untargeted screening, delivering sub-1 ppm mass accuracy, R²>0.9998 and calibration factor %RSD ≤2.6.

Main results and discussion

All configurations met or exceeded FDA method criteria for NDMA, NDEA, NEIPA, NDIPA and NDBA. Static headspace GC-MS achieved robust sensitivity without sample derivatization. Triple quadrupole GC-MS/MS provided exceptional selectivity and low matrix interference via SRM. Orbitrap GC-MS enabled confident identification of known and unknown impurities with accurate mass confirmation and isotopic pattern matching. Repeatability studies demonstrated peak area %RSD <7 at low ng/mL levels.

Benefits and practical applications

• High-throughput and simplified sample preparation with headspace sampling.
• cGMP-compliant data integrity and 21 CFR Part 11 readiness via Chromeleon CDS.
• Flexibility to switch between headspace and liquid injection for diverse analytes.
• Future-proofing workflows through untargeted screening and retrospective data mining.

Future trends and opportunities

As regulatory limits tighten, ultra-trace detection will rely increasingly on high-resolution accurate mass instruments and enhanced ion sources. Advances in dynamic headspace, automated derivatization and AI-driven data processing will expand the scope of genotoxic impurity screening. Real-time monitoring and in-process control using GC-Orbitrap systems may further accelerate quality assurance.

Conclusion

Thermo Fisher Scientific’s comprehensive GC-MS portfolio offers robust, sensitive and compliant solutions for nitrosamine impurity analysis. From headspace GC-MS to triple quadrupole and Orbitrap platforms, laboratories can meet current cGMP requirements and anticipate future regulatory challenges with confidence.

References

• WHO Information Note: Nitrosamine impurities, Update on nitrosamine impurities.
• ICH M7(R1) Guideline on DNA reactive (mutagenic) impurities.
• IARC Monographs 89: Smokeless Tobacco and N-Nitrosamines.
• EMA Temporary interim limits for NMBA, DIPNA and EIPNA in sartan medicines.
• FDA combined nitrosamine assay methods by GC-MS, GC-MS/MS and LC-HRMS.
• FDA NDMA in ranitidine safety information.
• USP <467> Organic volatile impurities, Interim Revision Announcement.