Nitrosamine impurities analysis solutions guide

Nitrosamine Impurities — Analysis Solutions Guide: Executive Summary

Significance of the topic

Nitrosamines are small, potent genotoxic impurities that have caused major regulatory scrutiny since 2018. Their formation in active pharmaceutical ingredients (APIs) or finished products can arise from nitrosation of secondary/tertiary amines in the presence of nitrite. Regulatory expectations demand confident detection, accurate quantitation, and robust control strategies to protect patient safety and avoid costly recalls. This guide summarizes analytical approaches and instrumentation that support both exploratory investigations and routine GMP-ready monitoring of nitrosamines, nitrite/nitrate, and related NDSRIs (Nitrosamine Drug Substance Related Impurities).

Objectives and overview of the guide

The primary goals are to present fit-for-purpose analytical solutions for each stage of nitrosamine impurity work: initial risk assessment and precursor monitoring, exploratory impurity discovery and confirmation, and high-throughput routine quantitation. The guide contrasts complementary technologies (LC-HRAM, LC-MS/MS triple quadrupole, GC-HRAM, ion chromatography) and supporting tools such as automated sample preparation and compliance-ready software to enable robust workflows.

Methodology and analytical approaches

Multiple, complementary analytical strategies are recommended depending on stage and purpose:

• Exploratory and confirmation: LC coupled to high-resolution accurate-mass (HRAM) MS (Orbitrap) to provide absolute mass confirmation and to resolve near-isobaric interferences (example: NDMA vs DMF 15N isotope requires high resolving power and ppm-level mass accuracy).
• Targeted routine quantitation: Triple-quadrupole LC-MS/MS (TSQ series) for sensitive, high-throughput assays with low limits of quantitation suitable for routine batch release testing.
• Volatile/small nitrosamines and fast separations: GC-HRAM MS for rapid multi-nitrosamine screening with high sensitivity and confirmation capability.
• Precursor monitoring (risk mitigation): Ion chromatography (IC) for nitrite/nitrate determination in excipients and APIs to assess nitrosation risk.
• Simultaneous Quantitation and Discovery (SQUAD): Integrated HRAM workflows that combine targeted calibration-based quantitation and untargeted acquisition in a single injection to capture known and novel impurities.
• Automation: Automated sample-preparation platforms to improve throughput, reduce contamination risk, and provide reproducible extracts for LC or GC analysis.

Instrumentation used

The guide highlights commercially available analytical platforms and ancillary components that enable the described workflows. Key systems referenced include:

• High-resolution MS: Thermo Scientific Orbitrap Exploris 120 (LC-HRAM) and Orbitrap Exploris GC (GC-HRAM).
• Triple-quadrupole MS: Thermo Scientific TSQ Altis Plus, TSQ Quantis, and TSQ Quantis Plus for targeted LC- or GC-MS/MS quantitation.
• UHPLC/HPLC: Thermo Scientific Vanquish Flex and Vanquish Core systems, Acclaim 120 and Hypersil GOLD columns for robust separations.
• GC columns: TraceGOLD TG-1701MS for volatile nitrosamine separations.
• Ion chromatography: Thermo Scientific Dionex ICS-6000 HPIC (RFIC) with IonPac AS19 and other high-capacity columns for nitrite/nitrate analysis.
• Automated sample prep: Thermo Scientific TriPlus RSH autosampler/workflow for unattended extraction and solvent exchange to LC/GC.
• Software and compliance: Chromeleon Chromatography Data System (CDS) for instrument control, data analysis, reporting and GMP-compliant audit trails.

Main results and discussion

The guide documents performance benchmarks and method attributes from application notes and case examples:

• LC-HRAM (Orbitrap) can resolve challenging interferences; the NDMA/DMF isotope example demonstrates that sufficient resolving power and ~ppm mass accuracy are required to avoid false positives when chromatographic co-elution occurs.
• LC-MS/MS triple-quadrupole workflows delivered low LOQs in a metformin matrix: ~5 ppb using APCI and ~10 ppb using HESI, with stable chromatography across >1,000 injections—suitable for routine high-throughput screening.
• GC-HRAM methods achieved rapid separation of 15 nitrosamines in under 12 minutes, with method LOQs on the order of 2 ppb (well below typical regulatory limits), and robust performance over continuous multi-day operation.
• IC-MS methods quantified nitrite and nitrate in microcrystalline cellulose from ~1 to 150 ppb with minimal sample prep, enabling direct assessment of nitrosation risk factors in excipients.
• Automated sample preparation (TriPlus RSH) demonstrated improved throughput, reduced contamination risk, and reproducible internal standard performance across many injections.
• SQUAD workflows permit one-injection targeted quantitation plus untargeted discovery, improving the laboratory’s ability to detect unexpected NDSRIs while maintaining quantitation for regulated analytes.

Benefits and practical applications

The combined analytical toolbox supports multiple practical needs:

• Regulatory compliance: Instruments and software designed for trace-level detection combined with audit-trailed data handling help meet evolving global nitrosamine requirements.
• Risk mitigation: Routine nitrite/nitrate monitoring and precursor assessment reduce the likelihood of nitrosamine formation during manufacture and storage.
• Flexibility: Choice of HRAM or triple-quad approaches lets labs prioritize confirmation confidence (HRAM) or throughput and routine quantitation (triple quad).
• Operational efficiency: Automation and robust chromatography decrease hands-on time and increase sample throughput while maintaining reproducibility.

Future trends and potential applications

Expected developments and opportunities include:

• Increased adoption of hybrid workflows (SQUAD) that combine quantitative regulatory analyses with untargeted surveillance to capture emerging impurities and NDSRIs without separate runs.
• Broader use of HRAM GC-MS and LC-MS to reduce false positives in complex matrices, particularly where near-isobaric interferences exist.
• Greater integration of automated sample preparation and online sample handling to scale testing capacity while preserving data quality and chain-of-custody for GMP labs.
• Standardization and harmonization of method performance criteria across regulators, leading to shared best practices for LOQs, validation approaches, and risk-based monitoring strategies.
• Advances in software-driven data mining and chemometrics to accelerate unknown impurity annotation from untargeted datasets.

Conclusion

Effective nitrosamine control requires a layered analytical strategy: robust precursor monitoring by IC, targeted high-throughput quantitation by triple-quadrupole LC- or GC-MS/MS, and high-confidence confirmation and discovery by HRAM LC- or GC-MS. Automation and compliance-ready software are essential enablers for reproducible, GMP-aligned workflows. Implementing complementary technologies and hybrid acquisition strategies improves detection confidence, reduces false positives, and helps manufacturers meet stringent regulatory expectations.

References

The brochure references multiple application notes, articles and product materials from Thermo Fisher Scientific. Representative citations in standard form are listed below:

1. Thermo Fisher Scientific. HRAM LC-MS method for the determination of nitrosamine impurities in drugs. Application note.
2. Thermo Fisher Scientific. Highly sensitive and robust LC-MS/MS solution for quantitation of nitrosamine impurities in metformin drug products. Application note.
3. Thermo Fisher Scientific. GC Exploris HRAM validation of 15 nitrosamines in metformin drug substance. Application note.
4. Thermo Fisher Scientific. Determination of nitrite and nitrate from microcrystalline cellulose by ion chromatography. Application note.
5. Thermo Fisher Scientific. An automated sample preparation workflow for the analysis of nitrosamines in metformin. Application note.
6. Thermo Fisher Scientific. Chromeleon Chromatography Data System (CDS). Product brochure and software documentation.
7. Thermo Fisher Scientific. Vanquish and Acclaim UHPLC/HPLC platforms. Product literature.