NEMC: Unparalleled Performance of Advanced Electron Ionization GC-MS/MS Technology for the Determination of Nitrosamines in Drinking Water

Significance of the Topic

Trace levels of nitrosamines in drinking water represent a growing public health concern due to their carcinogenic potential. Regulatory agencies worldwide are setting increasingly stringent limits, driving the need for highly sensitive and selective analytical methods. Advanced GC-MS/MS approaches offer the ability to detect ultra-trace nitrosamine concentrations with minimal false positives.

Objectives and Study Overview

This study evaluated the quantitative performance of the Thermo Scientific TSQ 9000 triple quadrupole GC-MS/MS system equipped with the Advanced Electron Ionization (AEI) source for nitrosamine analysis in drinking water. Seventeen water samples from European testing facilities were analyzed to demonstrate real‐world applicability at sub-ppt levels.

Methodology and Instrumentation

Water samples (1 L) were spiked with deuterated surrogates and concentrated by activated charcoal SPE based on a modified EPA 521 protocol. Calibration standards ranged from 0.05 to 100 ng/L equivalent in water extracts.

Extracts were analyzed by GC-MS/MS in timed-SRM mode without data smoothing. Key performance metrics included instrument detection limits (IDL), limits of quantitation (LOQ), linearity, precision, carryover, and matrix recovery.

Used Instrumentation

• Thermo Scientific Trace 1310 Gas Chromatograph
• Thermo Scientific TSQ 9000 Triple Quadrupole Mass Spectrometer with AEI source
• Restek Carbofrit inlet liner
• TraceGOLD TG-1701MS column (30 m × 0.25 mm, 0.5 µm)

Key Results and Discussion

The AEI source achieved IDLs from 0.003 to 0.045 ng/L (0.003–0.045 ppt w/v) on‐column, surpassing typical electron ionization sensitivity. Method LOQs ranged between 0.1 and 0.5 ng/L in drinking water, verified by ion-ratio criteria (<30% deviation), peak area RSD (<15%), and co-elution within 0.01 min.

Linearity was excellent across 0.05–20 ng/L (R2 > 0.999) with response factor RSD < 5%. Recovery of nitrosamines fortified at 50 ng/L ranged from 80.7% to 111.1%, within defined acceptance limits. No carryover was observed following high‐level injections.

Analysis of 17 real samples revealed total nitrosamine concentrations between 0.9 and 4.5 ng/L, with NDMA, NDEA, and NDBA most frequently detected below the 10 ng/L notification threshold.

Benefits and Practical Applications

• Unrivaled sensitivity for sub-ppt nitrosamine detection in water
• High selectivity through timed-SRM reduces matrix interferences
• Rapid chromatographic separation (<9 min) supports high-throughput testing
• Robust precision and linearity across wide concentration ranges

Future Trends and Opportunities

• Integration of automated sample preparation to increase laboratory throughput
• Development of multiplexed ionization sources for broader contaminant panels
• Advances in data processing and AI-assisted quantitation
• Emerging regulations driving routine monitoring at ever-lower concentration levels

Conclusion

The TSQ 9000 GC-MS/MS system with AEI source delivers unparalleled quantitative performance for nitrosamine determination in drinking water. Its sensitivity, selectivity, and throughput make it an ideal platform for routine environmental monitoring and regulatory compliance.

References

1. Mitch W. A.; Sharp J. O. N-nitrosodimethylamine (NDMA) as a drinking water contaminant: A review. Environ. Eng. Sci. 2003, 20(5), 389–404.
2. Sedlak D. L.; Deeb R. A. Sources and fate of nitrosamines and its precursors in municipal wastewater treatment plants. Water Environ. Res. 2005, 77(1), 32–39.
3. California Water Boards. NDMA and Other Nitrosamines - Drinking Water Issues. https://www.waterboards.ca.gov/drinking_water/certlic/drinkingwater/NDMA.html (accessed 4/12/2018).
4. Ontario Ministry of the Environment and Energy. Regulation Made Under the Ontario Water Resources Act: Drinking Water Protection Larger Water Works. April 24, 2003.