Ensuring drinking water quality through a single method of VOCs analysis and taste- and odor-causing substances

Importance of the Topic

The analysis of volatile organic compounds (VOCs) alongside taste-and-odor-producing metabolites such as 2-methylisoborneol (2-MIB) and geosmin in drinking water is critical to ensure public health and consumer acceptance. While Brazilian regulations specify maximum limits for VOCs, they lack criteria for off-flavor substances. A unified analytical approach enhances monitoring efficiency and regulatory compliance.

Study Objectives and Overview

This work presents the development and validation of a single method combining purge-and-trap (P&T) dynamic headspace with gas chromatography–tandem mass spectrometry (GC-MS/MS) to quantify VOCs, 2-MIB, and geosmin in one run. The study aligns with CONAMA 357, Portaria GM/MS 888/21, and USEPA Method 524.4, addressing the gap in taste-and-odor compound regulation.

Methods and Instrumentation

Dynamic headspace purge-and-trap was employed to concentrate analytes from aqueous samples. Nitrogen served as the purge gas and helium as the carrier gas. An EST Evolution2 P&T concentrator with a Centurion autosampler interfaced to a Shimadzu GCMS-TQ8050 NX. Separation used a 0.25 mm × 30 m × 1.4 μm SH-I-624Sil MS column with an 18-minute runtime. Detection combined Selected Ion Monitoring (SIM) for VOCs and Multiple Reaction Monitoring (MRM) for 2-MIB and geosmin.

Main Results and Discussion

Calibration employed six to seven concentration levels, yielding coefficients of determination (R²) above 0.995 for all targets. Limits of quantification were set at 0.25 ppb for most VOCs, 5 ppb for dioxane and 2-MIB, and 10 ppt for geosmin. Chromatograms demonstrated clear separation and sensitive detection down to low ppt levels. The method achieved simultaneous analysis without sacrificing analytical performance.

Benefits and Practical Applications

• Comprehensive monitoring of VOCs and off-flavor compounds in a single run reduces analysis time.
• Enhanced sensitivity meets stringent regulatory requirements.
• Operational simplicity via unified P&T-GC-MS/MS configuration saves resources.
• Applicable to routine quality control in water treatment facilities and environmental laboratories.

Future Trends and Potential Applications

Further innovations may include automation of sample preparation, integration with real-time monitoring sensors, and expansion to other volatile contaminants such as endocrine disruptors. Advances in sorbent materials and miniaturized P&T systems could enable field-deployable devices for on-site water quality assessment.

Conclusion

The developed P&T-GC-MS/MS method provides a robust, efficient, and sensitive tool for simultaneous quantification of VOCs, 2-MIB, and geosmin in drinking water, supporting compliance with Brazilian and international guidelines. Its single-run capability and low detection limits make it suitable for comprehensive water quality monitoring.