Determination of Nitrosamine Impurities Using the High-Resolution Agilent 6546 LC/Q-TOF

Significance of the Topic

The presence of trace-level nitrosamine impurities in angiotensin II receptor blocker (ARB) pharmaceuticals constitutes a major safety concern due to their probable carcinogenicity and recent product recalls.
High-resolution liquid chromatography–mass spectrometry (LC/MS) methods are critical for detecting these compounds at low ng/mL levels and ensuring regulatory compliance.

Objectives and Study Overview

This study aimed to develop and validate a single high-resolution LC/MS/MS approach using the Agilent 6546 LC/Q-TOF to detect and quantify six USFDA-listed nitrosamines and a total of eleven related impurities in ARB drug products.

Methodology and Used Instrumentation

An Agilent 1290 Infinity II UHPLC system equipped with a Poroshell HPH C18 column (2.1 × 100 mm, 1.9 µm) was paired with an Agilent 6546 LC/Q-TOF using positive-mode APCI.
Key chromatographic conditions included a 40 °C column temperature, 0.4 mL/min flow rate, and a gradient from 1 % to 95 % methanol with 0.2 % formic acid over 10 minutes.
The mass spectrometer operated over 70–170 m/z with dynamic segment-specific fragmentor voltages.
Data acquisition and analysis were performed with Agilent MassHunter and a custom personal compound database and library (PCDL) employing a 1/x-weighted linear calibration and the Find by Formula algorithm.

Main Results and Discussion

Calibration was linear from 0.05 to 100 ng/mL (R2 ≥ 0.996), with limits of detection between 0.05 and 0.25 ng/mL and LOQs from 0.1 to 0.5 ng/mL.
A representative extracted ion chromatogram demonstrated clear separation of all eleven nitrosamine peaks within a 10-minute run time.
Accuracy across calibration levels was within ±20 %, and reproducibility showed coefficients of variation below 15 %.

Benefits and Practical Applications

The validated method enables quantitative monitoring of nitrosamine impurities at trace levels in ARB formulations, supporting quality control, regulatory testing, and risk mitigation in pharmaceutical manufacturing.

Future Trends and Possibilities

Expansion of high-resolution accurate-mass (HRAM) screening workflows to include additional nitrosamine analogues and other impurity classes.
Integration of automated sample preparation and data-processing pipelines for high-throughput regulatory testing.
Harmonization of methods across laboratories and development of standardized databases to enhance cross-platform compatibility.
Exploration of orthogonal ionization techniques and advanced mass spectrometers to further lower detection limits.

Conclusion

The high-resolution Agilent 6546 LC/Q-TOF method provides a robust, sensitive, and reproducible approach for the simultaneous detection and quantification of multiple nitrosamine impurities in ARB drug products, ensuring compliance with regulatory guidelines and safeguarding patient safety.

References

1. USFDA guidance document: Development and validation of a RapidFire–MS/MS method for screening of nitrosamine impurities.
2. USFDA guidance document: Liquid chromatography–high resolution mass spectrometry (LC/HRMS) method for the determination of six nitrosamine impurities in ARB drugs.