A Fully Automated Liquid-Liquid Extraction for 2-Methylisoborneol and Geosmin in water

Significance of the topic

2-methylisoborneol (MIB) and geosmin are earthy off-flavour compounds produced by cyanobacteria and actinomycetes in surface water sources. Humans detect these odours at concentrations as low as 5 ng/L for MIB and 30 ng/L for geosmin, making sensitive testing essential for drinking water quality.

Goals and overview of the study

This work demonstrates a fully automated liquid–liquid extraction (LLE) workflow for trace analysis of MIB and geosmin in water. It aims to miniaturize sample preparation, lower solvent consumption, and increase sample throughput while achieving low detection limits to support rapid water quality monitoring.

Methodology and instrumentation

6 mL of water sample is transferred to a 10 mL high-recovery vial and processed using the prep-ahead function of GERSTEL Maestro software. Calibration standards (2–100 ng/L) are prepared by spiking and automated addition of internal standard.

• Dual Head GERSTEL MPS xt autosampler
• GERSTEL Cooled Injection System (CIS) 4 PTV inlet
• GERSTEL QuickMix shaker
• Anatune CF-200 centrifuge
• Agilent 7890B GC with DB-5MS UI column
• Agilent 5977B mass spectrometer (high-efficiency source)

After solvent addition (0.2 mL dichloromethane), samples are shaken (3 min, 3000 rpm), centrifuged (5 min, 4500 rpm), and 10 µL of the organic layer is injected in large volume injection solvent vent mode, ramping from 10°C to 280°C.

Main results and discussion

Linearity for both analytes was excellent (R2 > 0.999). Precision at the 2 ng/L level showed relative standard deviations below 10% for MIB and geosmin. Chromatograms achieved sufficient resolution despite minor baseline noise. Automated prep combined with concurrent GC analysis reduced per-sample time by approximately 15 minutes compared to manual LLE.

Benefits and practical applications

The automated method reduces solvent use by an estimated 394 L per year (30 samples/day, 260 days/year), lowers laboratory consumable costs, and frees analyst time for other tasks. Unattended operation improves safety and enables rapid response in water treatment facilities.

Future trends and possibilities

Further development may extend the automated extraction platform to other trace-level water contaminants. Integration with green solvents, online data evaluation, and remote monitoring systems will enhance sustainability and real-time quality control in environmental analysis.

Conclusion

The fully automated LLE workflow for MIB and geosmin offers robust sensitivity, reproducibility, and significant resource savings. It supports efficient water quality monitoring by meeting stringent detection limits with minimal manual intervention.

Instrumentation used

• Dual Head GERSTEL MPS xt
• GERSTEL CIS 4 PTV inlet
• GERSTEL QuickMix
• Anatune CF-200 centrifuge
• Agilent 7890B GC
• Agilent 5977B MS
• Maestro software, MassHunter B.07.04