Robust analysis of taste and odor compounds in drinking water using purge and trap and single quadrupole GC-MS

Importance of the topic

Unpleasant taste and odor in drinking water, caused by trace volatile compounds such as geosmin and 2-methylisoborneol (2-MIB), can trigger consumer concerns despite posing no direct health risk. Humans can detect these compounds at ng/L levels, making sensitive monitoring essential for water utilities to manage consumer complaints and ensure aesthetic water quality.

Study objectives and overview

This study demonstrates a streamlined, solvent-free approach for quantifying geosmin and 2-MIB in drinking water using a purge-and-trap (P&T) concentrator coupled to a single-quadrupole GC-MS. Key performance metrics—linearity, method detection limits (MDLs), precision, accuracy, and robustness—are evaluated in accordance with Standard Method 6040C.

Methodology and instrumentation

Samples of deionized water were spiked with geosmin and 2-MIB calibration standards (2–100 ng/L) and two internal standards (2-isobutyl-3-methoxypyrazine and 2,4,6-trichloroanisole at 30 ng/L). The Teledyne Tekmar Atomx XYZ P&T system enriched headspace volatiles, which were desorbed and transferred to a Thermo Scientific TRACE 1310 gas chromatograph. Separation occurred on a TraceGOLD TG-VMS capillary column (20 m × 0.18 mm × 1 µm) with helium carrier gas. Detection used a Thermo Scientific ISQ 7000 single-quadrupole MS in selected ion monitoring (SIM) mode. Data acquisition and processing were performed with Chromeleon CDS software.

Main results and discussion

• Linearity: Calibration over 2–100 ng/L achieved R² ≥ 0.996 and average calibration factor %RSD < 7.
• Sensitivity: MDLs of 0.37 ng/L for 2-MIB and 0.33 ng/L for geosmin met method requirements, with no blank interference.
• Precision and accuracy: At 50 ng/L, recoveries were 94.5 % (2-MIB) and 104.3 % (geosmin) with %RSDs of 6.4 and 7.0, respectively; primary ion ratios remained within ±20 % of calibration values.
• Robustness: In a 132-injection sequence over 90 hours with no maintenance, continuing calibration checks at 20 ng/L averaged recoveries of 120 % (2-MIB) and 110 % (geosmin) with %RSDs of 14.3 and 11.0; confirmation ion ratios stayed within ±20 % tolerance.

Benefits and practical applications

This P&T-GC-MS workflow eliminates solvent usage, reduces sample preparation labor, and supports high throughput with automated, unattended operation. The modular design and NeverVent technology minimize downtime for service, making it ideal for environmental testing laboratories requiring consistent, reliable results.

Future trends and opportunities

Further automation and integration with laboratory information management systems (LIMS) can streamline operations. Advancements in faster trap cycling, expanded analyte panels, and coupling with high-resolution mass spectrometry may enhance sensitivity and selectivity. Remote monitoring and predictive maintenance could further increase uptime and data integrity.

Conclusion

The described method fulfills Standard Method 6040C criteria for geosmin and 2-MIB analysis in drinking water, delivering excellent sensitivity, precision, accuracy, and long-term robustness in a solventless, high-throughput workflow.

Used instrumentation

• Teledyne Tekmar Atomx XYZ purge-and-trap concentrator
• Thermo Scientific TRACE 1310 gas chromatograph
• Thermo Scientific ISQ 7000 single-quadrupole MS with ExtractaBrite ion source
• TraceGOLD TG-VMS capillary column (20 m × 0.18 mm × 1 µm)
• Chromeleon chromatography data system

Reference

• Standard Methods for the Examination of Water & Wastewater, Method 6040C, 2005.
• Young WF et al., “Taste and odor threshold concentration of potential potable water contaminants,” Water Research, 30(2), 331–340 (1996).
• United States Geological Survey, Algal toxins and taste-odor compounds fact sheet, accessed 2020.
• Kim H. et al., “Application of SPE followed by large-volume injection GC/MS for analysis of Geosmin and 2-Methylisoborneol in water,” Analytical Methods, 7, 6678–6685 (2015).
• Thermo Scientific Application Note AN73471: In-Tube Extraction Dynamic Headspace (ITEX-DHS) for odorants in water.