Mold Odor Analysis Using a Purge and Trap Multimatrix Autosampler

Importance of the Topic

This study addresses the challenge of detecting trace mold odor compounds such as geosmin, 2-methylisoborneol (MIB), isobutylmethoxypyrazine (IBMP) and 2,4,6-trichloroanisole (TCA) in drinking water. Although these compounds are not a health hazard, their extremely low sensory thresholds (below 10 parts-per-trillion) can lead consumers to question water safety. Highly sensitive and automated analytical workflows are therefore crucial for routine water quality monitoring.

Objectives and Study Overview

The aim was to develop and validate a fully automated purge-and-trap headspace method using a multimatrix autosampler to quantify mold odor compounds at part-per-trillion levels. Key performance metrics included calibration linearity, method detection limits (MDLs), precision (%RSD) and carryover.

Methodology and Instrumentation

Drinking water samples (25 mL) containing 10 % NaCl were sparged with helium for 10 minutes at 100 mL/min. Volatile analytes were concentrated on a Tenax sorbent trap, thermally desorbed at 225 °C for 4 minutes and transferred to a GC/MS system in selective ion monitoring (SIM) mode.

Instrumentation Used

• Teledyne Tekmar Atomx multimatrix purge-and-trap autosampler
• Agilent 7890A gas chromatograph coupled to 5975C mass selective detector
• J&W DB-624 capillary column (20 m × 0.18 mm × 1.0 µm)
• Tenax sorbent analytical trap

Main Results and Discussion

Calibration over 1 ppt to 100 ppt yielded coefficients of determination (r²) ≥ 0.999 and %RSD ≤ 4.3 % for all analytes. Method detection limits were all below 0.12 ppt, well beneath typical human odor thresholds. Carryover remained below 0.31 % after a 100 ppt injection. These metrics confirm the method’s suitability for ultra-trace analysis.

Benefits and Practical Applications of the Method

• Complete automation of sample preparation increases throughput and reduces labor.
• Sensitivity at part-per-trillion levels ensures reliable detection of odorants.
• Flexibility to analyze water, soil and methanol extracts in one run.
• Compatibility with EPA and specialized methods for routine QA/QC.

Future Trends and Opportunities

Further development may integrate high-throughput screening of emerging odorants and expand to real-time field deployable systems. Coupling with high-resolution mass spectrometry could enhance compound identification and expand applicability to complex environmental matrices.

Conclusion

The automated purge-and-trap GC/MS method demonstrated excellent sensitivity, precision and low carryover for mold odor compounds at part-per-trillion levels. Full automation via the Atomx autosampler streamlines workflow, delivering reliable water quality data while improving laboratory efficiency.