Optimising Analytical Performance and Extending the Application Range of Thermal Desorption for Monitoring Air Indoors and Inside Vehicle Cabins

Significance of the Topic

Thermal desorption coupled with gas chromatography mass spectrometry delivers high sensitivity and selectivity for volatile organic compounds in indoor and vehicle cabin air. Detecting trace pollutants is critical for occupant health assessment exposure studies and quality control of building materials and processes. This approach reduces solvent use and automates sample preparation achieving low detection limits and robust performance.

Objectives and Study Overview

This work aims to optimize analytical performance of thermal desorption GC MS and broaden its application range for indoor air and vehicle cabin monitoring. Key goals include enhancing sampling efficiency minimizing artifacts improving sensitivity and enabling repeated analysis and real time integration. Examples illustrate optimized methods validated against international standards and novel sampling concepts.

Applied Methodology and Instrumentation

The thermal desorption workflow consists of primary sorbent tube or direct desorption sampling followed by secondary focusing trap and injection into GC or GC MS. Sampling options covered include:

• Evacuated canisters and Tedlar bags for ultravolatiles
• Pumped sorbent tubes packed with single or multi bed materials
• Axial and radial diffusive samplers for passive monitoring
• Direct desorption of solids liquids and breath samples

Method optimization addresses sorbent selection conditioning storage leak testing and controlled carrier gas flows to ensure recoveries above 95 including split re collection for repeat analysis.

Used Instrumentation

• Automated thermal desorber with secondary focusing trap
• Gas chromatograph and mass spectrometer detector
• Sampling pumps and diffusive sampling caps
• Field and Laboratory Emission Cell FLEC for materials testing
• Bio VOC alveolar air breath sampler
• Real time detectors such as process mass spectrometers and electronic noses

Main Results and Discussion

Optimization yielded concentration factors up to 106 detection down to ppt levels and precision typically of 1 to 2 percent. Multi sorbent tubes enabled broad volatility range capture while minimizing artifacts even at high humidity. Radial diffusive samplers offered short term high resolution monitoring and the FLEC device met prENV 13419 requirements for material emission testing. Breath sampler studies highlighted real time decay profiles of solvents and differentiation between smoker and non smoker exposures.

Benefits and Practical Applications

• Trace VOC profiling in indoor environments and vehicle cabins
• Ventilation testing and tracer gas studies
• Emissions screening of building materials paints adhesives
• Odour and fragrance characterisation
• Occupational and personal exposure assessment
• Semiconductor clean room monitoring

Future Trends and Potential Uses

Advances will include portable online thermal desorption systems with integrated real time detection data fusion and automated calibration. New high capacity sorbents and miniaturized traps will enable continuous networked monitoring. AI driven spectral analysis will facilitate non targeted screening and early warning of indoor air quality issues.

Conclusion

Optimized thermal desorption GC MS methods offer a versatile high sensitivity platform for diverse indoor air monitoring applications. Innovations such as repeat split re collection FLEC sampling and breath analysis extend utility for exposure assessment material emission testing and real time profiling. Adoption of these techniques supports improved environmental health research and quality assurance.

References

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