AUTOMATED LIQUID-LIQUID EXTRACTION OF GEOSMIN IN WATER BY GC-MS/MS

Significance of the Topic

Detecting geosmin in water at trace levels is essential for environmental monitoring and maintaining drinking water quality. Human sensory thresholds for taste and odor compounds often lie below instrumental detection limits, driving the need for highly sensitive analytical techniques that comply with regulatory standards such as the European Water Framework Directive.

Objectives and Study Overview

This study aims to develop and validate a fully automated liquid–liquid extraction (LLE) method for geosmin in water, coupled with GC–MS/MS analysis. The goal is to achieve limits of detection (LODs) in the low ng/L range while improving throughput, reproducibility, and reducing manual labor.

Methodology

Water samples were spiked with geosmin standards at 1 ng/L and 5 ng/L using a robotic autosampler. Automated LLE was performed by adding organic solvent and agitating via a robotic shaker. Following phase separation in a robotic centrifuge, a large‐volume injection of the organic layer was carried out using a cool injection system.

Instrumentation

• GERSTEL Robotic/Robotic Pro Dual Head autosampler
• GERSTEL Cooled Injection System (CIS) 4 with PTV inlet
• GERSTEL QuickMix module
• Agilent 7890A GC coupled to 7010A triple quadrupole MSD
• Anatune CF-200 Robotic Centrifuge
• Maestro and MassHunter software

Key Results and Discussion

MRM chromatograms for the m/z 112→83 transition demonstrated clear, well‐resolved peaks for 1 ng/L and 5 ng/L spiked samples, with excellent signal-to-noise ratios. Automation minimized variability common in manual LLE workflows and ensured consistent recoveries at low concentration levels.

Benefits and Practical Applications

• Enhanced sensitivity and selectivity for trace geosmin detection
• High sample throughput with reduced hands-on time
• Improved reproducibility and lower risk of human error
• Rapid turnaround to support water quality decision-making

Future Trends and Opportunities

Further method refinement could push LODs below 1 ng/L. Expansion to other odor-active compounds, integration with laboratory information management systems (LIMS), and the adoption of greener solvents and microextraction approaches represent promising directions for environmental and water analysis.

Conclusion

The combined use of automated LLE and GC–MS/MS with a triple quadrupole detector offers a robust solution for ultra-trace geosmin analysis in water. This approach meets regulatory and sensory detection requirements while delivering high throughput and operational efficiency.