MONITORING FOR ‘TASTE AND ODOUR COMPOUNDS’ INCLUDING GEOSMIN AND MIB IN POTABLE WATER USING THE AGILENT 7000 TRIPLE QUADRUPOLE GC/MS

Importance of the Topic

The presence of trace taste and odor compounds in drinking water often triggers consumer complaints despite generally low health risks. Compounds such as geosmin and 2-methylisoborneol (MIB) exhibit sensory thresholds at low ng/L levels and originate from microbial activity, natural organic decay, industrial discharges or by-products of treatment. Rapid and sensitive analytical screening is essential for identifying and controlling these off-flavors in potable water supplies.

Objectives and Study Overview

This study presents the development of a targeted GC/MS/MS method on an Agilent 7000 Triple Quadrupole system for quantifying 20 key taste and odor compounds. The analyte suite includes terpenoids (geosmin, MIB), phenols, halogenated anisoles, pyrazines and dioxolanes. The method aims to achieve detection limits of 1 ng/L and a linear calibration range up to 50 ng/L to support routine monitoring.

Methodology and Instrumentation

Sample preparation employs liquid–liquid extraction of 1 L water with 100 mL dichloromethane, concentration to 0.5 mL, and addition of D8-naphthalene internal standard. Analysis is carried out on an Agilent 7890A GC with multi-mode inlet coupled to an Agilent 7000 Triple Quadrupole MS operating in EI-MRM mode.

• Injection volume: 2 µL in splitless mode
• Column: 30 m × 0.25 mm × 0.25 µm HP-5MS Ultra Inert
• Oven program: 35 °C (1 min) → 150 °C at 10 °C/min → 270 °C at 20 °C/min (18.5 min total)
• Carrier gas: helium, constant flow
• Source/quad/transfer line temperatures: 230 °C/150 °C/300 °C

Main Results and Discussion

The method consistently achieved limits of detection at 1 ng/L for all 20 compounds. Calibration curves from 0 to 50 ng/L exhibited excellent linearity. Sample analyses demonstrated strong signal-to-noise ratios even near the reporting limit: geosmin at 1.1 ng/L (S/N 128:1), MIB at 26.3 ng/L (S/N 53:1), 4-chloroanisole at 2.1 ng/L (S/N 1653:1) and 2,3,4-trichloroanisole detected at 0.1 ng/L (S/N 138:1), indicating potential for sub-ng/L quantitation after full validation.

Benefits and Practical Applications

This GC/MS/MS approach offers high sensitivity, selectivity and throughput for water utilities and QA/QC laboratories. It supports rapid identification of off-flavor sources, informs treatment adjustments and enhances consumer confidence in drinking water quality.

Future Trends and Potential Uses

Further method validation to regulatory standards could lower reporting limits. The workflow can be extended to surface water, wastewater or other environmental matrices. Integration with automated sample preparation and data processing may enable real-time odor monitoring and early warning systems.

Conclusion

An efficient, robust analytical method using Agilent 7000 Triple Quadrupole GC/MS has been established for 20 common taste and odor compounds in drinking water. Its sub-ng/L sensitivity and broad calibration range make it a valuable tool for environmental monitoring and water quality management.

Reference

1. H. R. Rogers, “Factors causing off-taste in waters, and methods and practices for the removal of off-taste and its causes,” DETR/DWI 5008/1, 2001.
2. Environment Agency, “The determination of taste and odour in drinking waters (2010),” Methods for the examination of waters and associated materials, England and Wales, UK.