Combined Determination of 1,4-Dioxane and Nitrosamine Contaminants in Drinking Water

Importance of the Topic

The combined analysis of 1,4-dioxane and nitrosamine contaminants in drinking water addresses critical public health concerns. Both classes of compounds are suspected human carcinogens with regulatory limits at low parts-per-trillion. Traditional methods require separate extractions and analyses, consuming significant time, solvent, and instrument resources. A unified approach enhances laboratory efficiency while achieving stringent detection requirements.

Objectives and Study Overview

This work aimed to integrate EPA Methods 522 (1,4-dioxane) and 521 (nitrosamines) into a single solid‐phase extraction (SPE) workflow followed by one chromatographic run using concurrent solvent recondensation–large volume splitless injection (CSR-LVSI) with electron ionization GC-MS. Key goals included reducing sample preparation and analysis time, minimizing solvent usage, and attaining practical quantitation limits (PQLs) relevant to human health risk levels.

Methodology and Instrumentation

Samples (0.5 L) were passed through a single coconut charcoal SPE cartridge, eluted with dichloromethane to 10 mL extracts, and fortified with deuterated surrogates. A 50 µL CSR-LVSI injection was performed on an Agilent 7890A GC equipped with a 5975C MSD. A 10 m × 0.53 mm Rxi® deactivated guard column preceded a 30 m × 0.25 mm × 1 µm Rxi®-5Sil MS column. Electron ionization at 70 eV and selected ion monitoring (SIM) enabled sensitive detection. GC oven and flow programs were optimized for solvent focusing and rapid analysis.

Key Results and Discussion

– Calibration curves (eight levels) exhibited linearity (R = 0.994–0.999) with surrogates showing RSD < 4%.
– Initial PQLs (based on lowest calibration points) reached 10 ng/L for 1,4-dioxane and 0.5–2 ng/L for nitrosamines, though blank contamination required raising some reporting limits.
– NDMA was quantified at sub-ppt levels (0.63 ng/L) below its IRIS 1×10⁻⁶ risk level (0.7 ng/L).
– Recoveries for mid-level fortifications averaged 80–110% with RSDs < 10%.
– Combined SPE and CSR-LVSI reduced total workflow time for 20 samples from ~31.7 h (separate methods) to ~17.7 h, saving ~14 h and cutting solvent consumption.

Benefits and Practical Applications

• Single-cartridge extraction for multiple analytes minimizes shipping, handling, and storage requirements.
• CSR-LVSI with an unmodified splitless inlet delivers large-volume injections without specialized hardware.
• Reduced solvent use and faster turnaround enhance laboratory throughput for drinking water compliance testing.
• The approach is adaptable to volatile and semivolatile contaminants in environmental and industrial matrices.

Future Trends and Potential Uses

Laboratories may extend CSR-LVSI SPE integration to wastewater and hazardous waste analyses, potentially reducing sample volumes and handling risks. Further refinements in blank water purification and the adoption of high-resolution MS could lower detection limits while maintaining selectivity. Automation of CSR-LVSI workflows and exploration of greener extraction media will support sustainable analytical practices.

Conclusion

The unified SPE-CSR-LVSI-GC-MS method effectively quantifies 1,4-dioxane and nitrosamines at health-relevant levels, significantly reducing sample preparation time and solvent consumption. Attention to blank water quality is essential to maintain low reporting limits. This combined approach offers a practical, cost-effective solution for routine drinking water monitoring and can be adapted for broader environmental applications.

References

• Grimmett PE, Munch JW. Method development for the analysis of 1,4-dioxane in drinking water using solid-phase extraction and GC-MS. J Chromatogr Sci. 47(1):31 (2009).
• EPA. Revisions to the Unregulated Contaminant Monitoring Regulation (UCMR 3) for Public Water Systems. Fed Regist. May 2, 2012.
• Zhao YY, et al. Formation of N-nitrosamines from eleven disinfection treatments of seven surface waters. Environ Sci Technol. 42(13):4857 (2008).
• Pressman JG, et al. Concentration, chlorination, and chemical analysis of drinking water DBP mixtures: U.S. EPA’s Four Lab Study. Environ Sci Technol. 44(19):7184 (2010).
• Mitch WA, Sedlak DL. Formation of NDMA from dimethylamine during chlorination. Environ Sci Technol. 36(4):588 (2002).
• Andrzejewski P, Kasprzyk-Hordern B, Nawrocki J. NMEA and NDEA formation during water disinfection with chlorine. Global NEST J. 7(1):17 (2005).
• Padhye LP, Hertzberg B, Yushin G, Huang CH. Nitrosamine formation by nitrogen fixation on activated carbon. Environ Sci Technol. 45(19):8368 (2011).
• Munch JW, Bassett MV. Analysis of NDMA and other nitrosamines using SPE and GC-CI-MS/MS. J AOAC Int. 89(2):486 (2006).
• U.S. Department of Health & Human Services. Report on Carcinogens, Twelfth Ed. NTP, 2011.
• OSHA. Carcinogens standard 29 CFR 1910.1003. U.S. Dept. of Labor.
• WHO. N-Nitrosodimethylamine in Drinking Water, 2nd Addendum, 2006.
• EPA. RCRA Groundwater Monitoring List, Part 264 Appendix IX, 2012.
• EPA. Integrated Risk Information System (IRIS), 2013.
• Ontario Ministry of Environment. Method E3388: N-nitrosamines by GC-HRMS, 2010.
• EPA Method 521. Nitrosamines by SPE and GC-CI-MS/MS, 2004.
• Charrois JW, et al. Detecting nitrosamines in drinking water using ammonia PCI. Environ Sci Technol. 38(18):4835 (2004).
• You YW. Analysis of Nitrosamines in Drinking Water Using Agilent 5977A GC-MSD, 2013.
• Wilson B, Wylie P, Klee M. Large Volume Injection for GC Using PTV Inlet. Agilent, 1997.
• Magni P, Porzano T. Concurrent Solvent Recondensation Large Sample Volume Splitless Injection. J Sep Sci. 26(2003).
• U.S. Patent 6,955,709 B2.
• Cochran J. CSR-LVSI for EPA Method 8270 Semivolatiles. Restek App Note EVAN1331-UNV, 2011.
• Misselwitz M, Cochran J. LVI-TOFMS for pesticides and BFRs. Restek App Note EVAN1314-UNV, 2011.
• Thermo Fisher. Large Volume Splitless Injection for toxicology specimens. App Note 10014, 2007.
• Thermo Fisher. Pesticides and PCBs by LVI-ECD. App Note 10136, 2005.
• Biedermann M, Fiscalini A, Grob K. LVI-CSR with concurrent focusing. J Sep Sci. 27(2004).
• Rattray C, Cochran J, English C. Lowering 1,4-dioxane limits by LVI in splitless GC. Restek App Note EVAN1548-UNV, 2012.