Quantification of 8 Disinfection Byproducts from Water by Liquid-Liquid Extraction and Gas Chromatography-MassSpectrometry

Importance of the Topic

Disinfection byproducts (DBPs) form when common disinfectants react with natural organic matter in water. Their presence is linked to health risks such as cancer and neurological effects, making accurate monitoring crucial for ensuring safe drinking water.

Objectives and Study Overview

This study evaluates the performance of a Shimadzu GCMS-QP2020 NX system to quantify eight regulated DBPs in drinking water using liquid–liquid extraction and GC–MS according to EPA Method 551.1.

Methodology and Sample Preparation

• Sample buffering and extraction: 50 mL water buffered to pH 4.8–5.5, spiked with surrogate, extracted with MTBE and salts via liquid–liquid extraction.
• Standards: Calibration standards (5–200 ppb) prepared with internal standard (p-bromofluorobenzene) at 1 ppm; surrogate (decafluorobiphenyl) used for recovery correction.

Analytical Conditions

• Instrumentation: Shimadzu GCMS-QP2020 NX with SH-I-5Sil MS column (30 m × 0.25 mm, 0.25 µm).
• GC inlet: splitless, 240 °C; injection volume 1 µL; helium flow 1.2 mL/min.
• Oven program: 35 °C (16 min), ramp 40 °C/min to 220 °C (4.37 min).
• MS settings: EI source at 290 °C; full-scan and SIM acquisition; scan range 35–600 m/z; event times 0.3 s (scan), 0.05 s (SIM).

Instrumentation

• Shimadzu GCMS-QP2020 NX single quadrupole GC-MS system
• SH-I-5Sil MS capillary column
• LabSolutions Insight and GCMSsolution software

Main Results and Discussion

Six-point calibration produced correlation coefficients (r²) > 0.99 for all analytes. Signal-to-noise ≥ 10 at 5 ppb demonstrated adequate sensitivity. Recovery of surrogate matched calibration (± 10 %). Spike recoveries ranged 70–120 %, with chloral hydrate at 70 % due to limited stability. These results confirm robust quantification of eight DBPs at low concentration levels.

Benefits and Practical Applications

The GC-MS approach offers greater selectivity, sensitivity, and dynamic range than traditional GC-ECD methods. It enables simultaneous identification and quantification of known DBPs, supporting regulatory compliance and water quality monitoring in environmental, research, and industrial laboratories.

Future Trends and Potential Applications

• Integration of high-resolution MS for broader screening of emerging DBPs.
• Automation and online extraction for real-time monitoring.
• Extension to other water contaminants using advanced data analysis.

Conclusion

The developed GC–MS method based on EPA 551.1 provides reliable, sensitive quantification of eight halogenated DBPs in drinking water, suitable for routine analysis at regulatory levels.

Reference

• EPA Method 551.1: Determination of chlorination disinfection byproducts, chlorinated solvents, and halogenated pesticides/herbicides in drinking water by liquid-liquid extraction and GC/ECD.