Trace analysis of epichlorohydrin in drinking water using GC-MS coupled with purge and trap

Significance of the Topic

Epichlorohydrin (ECH) is a volatile organic compound widely used in polymer and chemical production. Due to its toxicity and probable carcinogenicity, regulatory bodies require trace-level monitoring of ECH in drinking water. Achieving detection down to 30 ppt is essential for public health protection and compliance with stringent U.S. EPA and European limits.

Objectives and Study Overview

This application note demonstrates a complete analytical workflow for quantifying ECH in drinking water at concentrations as low as 30 ppt. Key performance metrics—linearity, method detection limit (MDL), precision, accuracy, and robustness—are evaluated using a purge-and-trap (P&T) concentrator coupled with GC-MS.

Instrumentation Used

• Tekmar Lumin P&T concentrator with AQUATek LVA autosampler
• Thermo Scientific TRACE 1610 Gas Chromatograph
• Thermo Scientific ISQ 7610 Single Quadrupole Mass Spectrometer
• TraceGOLD TG-VMS analytical column (30 m × 0.25 mm, 1.4 µm film)
• HeSaver-H2Safer split/splitless injector
• Chromeleon CDS software for instrument control and data processing

Methodology and Instrumentation

Calibration standards of ECH (30–5 000 ppt) and internal standard fluorobenzene were prepared in methanol and spiked into 25 mL water samples. Samples were purged with nitrogen to release VOCs, trapped on the P&T sorbent, and thermally desorbed into the GC. The GC oven ramped from 35 °C to 240 °C over 14.9 min. The MS operated in Selected Ion Monitoring (SIM) mode (m/z 57, 49, 62) for enhanced sensitivity. System parameters were optimized to minimize water interference and ensure reproducible analyte transfer.

Main Results and Discussion

• Chromatography: Well-resolved ECH peaks with minimal water matrix effects using the P&T moisture control system.
• Linearity: Calibration curve exhibited r² ≥ 0.995 across 30–5 000 ppt.
• MDL: Achieved an MDL of 5 ppt for ECH (n=7, 30 ppt replicates).
• Precision and Accuracy: Mid-point checks (1 000 ppt) yielded precision ≤ 4.2% RSD and accuracy within 115%.
• Robustness: Over 124 sequential injections of 1 000 ppt standards showed consistent response (≈ 4.4% RSD).
• Helium Savings: The HeSaver-H2Safer injector extended helium cylinder life nearly fourfold, reducing operational costs.

Benefits and Practical Applications

The described P&T-GC-MS method delivers high sensitivity and reproducibility for routine monitoring of ECH in drinking water. It meets U.S. EPA and European detection requirements while lowering gas consumption and maintenance needs. Automation via the AQUATek LVA and unified control in Chromeleon CDS simplifies operation in high-throughput laboratories.

Future Trends and Opportunities

• Integration of enhanced sorbents and trap materials for broader VOC panels.
• Miniaturized and field-deployable P&T-GC-MS systems for on-site water analysis.
• Machine-learning-driven data analysis for rapid anomaly detection.
• Expansion of green analytical chemistry practices to further reduce solvent and gas use.

Conclusion

This study validates a robust, sensitive, and cost-efficient GC-MS method for trace epichlorohydrin analysis in drinking water. The combined use of P&T concentration, HeSaver-H2Safer injection, and SIM detection fulfills regulatory requirements and supports routine water quality monitoring.

References

• Sram R.J., Landa L., Samkova I. Effect of occupational exposure to epichlorohydrin on the frequency of chromosome aberrations in peripheral lymphocytes. Mutat. Res. 1983, 122, 59.
• Council Directive 98/83/EC of 3 November 1998 on the quality of water intended for human consumption. Official Journal of the European Communities, 1998, No. 330/32.
• Lucentini L., Ferretti E., Veschetti E., Sibio V., Citti G., Ottaviani M. Static headspace and purge-and-trap gas chromatography for epichlorohydrin determination in drinking water. Microchemical Journal 2005, 80, 89–98.
• Mattioda C. Low-level analysis of epichlorohydrin in drinking water by headspace trap-GC/MS. PerkinElmer Field Application Report, 2008.
• Thermo Scientific AppsLab Library. Parameters for ECH analysis by P&T-GC-MS.
• Thermo Scientific Helium Saver Calculator. Online tool for estimating gas savings.