Air Sampling of VOCs by SPME for Analysis by Capillary GC

Significance of the Topic

Volatile organic compounds VOCs in air and water pose health and environmental risks requiring reliable field sampling methods

Objectives and Study Overview

This study evaluates a portable SPME field sampler with a Carboxen PDMS 75µm fiber for sampling and storing VOCs under field and laboratory conditions

Methodology and Instrumentation

Air and water samples were extracted following US EPA Method 624 at 20ppb and in a nine compound mixture covering 400ppt to 400ppb range

• SPME portable field sampler with Carboxen PDMS 75µm fiber
• Storage conditions: sealed at –4 °C sealed ambient and unsealed ambient for three days
• Desorption: five minutes at 300 °C
• Capillary GC with SPB-1 Sulfur column 30 m × 0.32 mm ID, 4.0 µm film and GC/MS ion trap detection m/z 45–260

Key Results and Discussion

The Carboxen PDMS fiber retained analytes with negligible loss at –4 °C sealed and average loss less than 15 % when stored unsealed at ambient for three days, compared with over 90 % loss on a 100 µm PDMS fiber
Calibration curves for nine VOCs showed excellent linearity (R² ≥ 0.98) except 1,2-dichloroethane (R² = 0.953)
The unique pore structure of Carboxen-1006 prevented displacement of lighter compounds even at higher concentrations

Benefits and Practical Applications

The sampler eliminates gas bag shipment, simplifies field sampling and enables delayed lab analysis of trace level VOCs in air and water, providing a convenient and reliable workflow

Future Trends and Opportunities

Advances may include integration with portable GC/MS, real-time sensors, expanded adsorbent coatings and automated sampling platforms to broaden analyte coverage and improve on-site decision making

Conclusion

The portable SPME sampler with Carboxen PDMS fiber offers robust VOC sampling and storage capabilities supporting accurate trace analysis and streamlined field-to-lab workflows

Reference

US EPA Method 624
Sigma Aldrich Application Note 141
US Patent 5691206 and European Patent 0523092