Quantitative passive soil vapor sampling for VOCs--part 2: laboratory experiments

Area of Science:

• Environmental Science
• Analytical Chemistry
• Industrial Hygiene

Background:

• Passive samplers are increasingly used for environmental monitoring.
• Their performance under specific conditions, like low face velocities, requires validation.
• Comparison with established methods like EPA Method TO-15 is crucial.

Purpose of the Study:

• To evaluate the accuracy and precision of five different passive samplers for soil vapor monitoring.
• To assess the impact of varying concentrations and face velocities on sampler performance.
• To compare passive sampler results against Summa canister samples analyzed by EPA Method TO-15.

Main Methods:

• Controlled laboratory experiments exposing five passive samplers (Radiello, SKC Ultra, Waterloo Membrane Sampler, ATD tubes, 3M OVM 3500) to ten volatile organic compounds.
• Testing at 1, 10, and 100 ppmv with controlled humidity (∼80%), temperature (∼24 °C), and face velocity (∼5 cm min⁻¹).
• Comparison with Summa canister samples analyzed by EPA Method TO-15; low-uptake rate samplers tested under stagnant and low face velocity conditions.

Main Results:

• Passive samplers demonstrated accuracy within a factor of 2 and precision with relative standard deviation (RSD) < 15%.
• Performance was comparable to conventional Summa canister samples and EPA Method TO-15 analysis.
• Some volatile organic compounds presented challenges due to uptake rate uncertainties or recovery issues.

Conclusions:

• Passive samplers are a viable option for soil vapor concentration monitoring, providing reliable data.
• The study validates their use, particularly for volatile organic compounds, under tested laboratory conditions.
• Further research may be needed for specific challenging compounds or under different environmental scenarios.