Nitrosamines Analysis in Drinking Water Using GC/MS/MS — Meeting Equivalence to EPA Method 521

Importance of the topic

Trace levels of nitrosamines, such as N-nitrosodimethylamine (NDMA), in drinking water raise significant health concerns due to their carcinogenic potential.
Monitoring these contaminants reliably ensures water safety and regulatory compliance.

Objectives and study overview

This study established the Eurofins Eaton Analytical-Agilent Method 521.1 as an alternative to EPA Method 521 for nitrosamine analysis.
A two-phase evaluation compared traditional ion trap GC/MS (GC/IT) with triple-quadrupole GC/MS/MS and validated performance across three laboratories using Agilent 7010 and 7000 systems.

Methodology

Water samples were spiked with nitrosamine standards and internal/external surrogates then subjected to solid phase extraction on coconut charcoal cartridges.
Extracts were eluted with methylene chloride, dried, concentrated, and reconstituted with internal standard.
Chromatographic separation used a DB-1701 column with a splitless injection (1 µL) into a multimode inlet.
Detection employed multiple reaction monitoring in EI mode with optimized precursor-product ion transitions and collision energies.

Used Instrumentation

• Agilent 7890 Gas Chromatograph
• Agilent 7010 Triple Quadrupole GC/MS/MS with High-Efficiency Source
• Agilent 7000 Triple Quadrupole GC/MS/MS with Extractor Source
• Varian 4000 GC/IT for EPA Method 521 comparison
• Agilent 7693 Automatic Liquid Sampler and Multimode Inlet

Main results and discussion

Phase I demonstrated that GC/MS/MS achieved lower reporting limits and detection limits than GC/IT, reduced run time from ~30 min to ~13 min, and cut injection volume from 10 to 1 µL.
Strong quantitative correlation (R² > 0.99) was observed between GC/MS/MS and GC/IT for NDMA in field samples.
Phase II interlaboratory testing across Labs A, B (7010), and C (7000) yielded lowest concentration minimum reporting levels of 0.12–0.67 ng/L (7010) and 0.33–1.20 ng/L (7000), and detection limits of 0.037–0.46 ng/L (7010) and 0.12–0.60 ng/L (7000), all below EPA Method 521 criteria.
Calibration in all labs was linear over 0.0625–100 ng/L with R² > 0.99.

Benefits and practical applications

GC/MS/MS offers enhanced sensitivity, faster throughput, reduced maintenance from smaller injection volumes, and robust quantitative performance.
The method supports routine QA/QC, regulatory compliance, and high-volume environmental monitoring of nitrosamines.

Future trends and applications

Expansion of high-efficiency ion source technology to other trace organic contaminants.
Adaptation of the method to additional nitrosamine species and complex matrices.
Integration with automated sample preparation and high-throughput screening platforms.
Potential harmonization into international drinking water standards.

Conclusion

The EEA-Agilent Method 521.1 using triple-quadrupole GC/MS/MS is a validated, EPA-equivalent approach for sensitive, reliable analysis of nitrosamines in drinking water, offering significant advantages over obsoleted GC/IT technology.

Reference

• U.S. EPA Letter of Equivalency for EEA-Agilent Method 521.1, March 13, 2018.
• Magee, P. N. Toxicity of Nitrosamines: Their Possible Human Health Hazards. Food Cosmet. Toxicol. 1971, 9(2), 207–218.
• Mitch, W. A.; et al. N-Nitrosodimethylamine (NDMA) as a Drinking Water Contaminant: A Review. Environ. Eng. Sci. 2003, 20(5), 389–404.
• Munch, J. W. EPA Method 521: Determination Of Nitrosamines In Drinking Water By SPE and GC/MS/MS. U.S. EPA, 2005.