Partitioning between polyurethane foam and the gas phase: data compilation, uncertainty estimation and implications...

Area of Science:

• Environmental Chemistry
• Analytical Chemistry
• Air Quality Monitoring

Background:

• Polyurethane foam (PUF) is widely used for sampling semi-volatile organic compounds (SVOCs) in ambient air.
• Equilibrium partition coefficients (KPUF/G) are crucial for estimating breakthrough in active air sampling (AAS) and correcting passive air sampling (PAS).
• Existing methods for determining KPUF/G introduce uncertainties that affect derived air concentration values.

Purpose of the Study:

• To compile and analyze a comprehensive dataset of measured KPUF/G values from the literature.
• To assess the inherent uncertainties associated with KPUF/G measurements and their impact on air sampling parameters.
• To provide recommendations for quantifying and reporting uncertainties in air concentration measurements obtained via PAS.

Main Methods:

• Compiled a dataset of 547 measured KPUF/G values for 281 chemicals from peer-reviewed literature.
• Compared measured log KPUF/G with predicted values to identify potential experimental biases.
• Analyzed the uncertainty propagation from KPUF/G and sampling rate (SR) to effective air volume (Vair).

Main Results:

• The uncertainty of unbiased log KPUF/G values is estimated to be at least 0.2 log units at 15 °C, and likely higher.
• Inherent uncertainties in sampling rates (SR) and breakthrough volumes for AAS are estimated to be at least 50%.
• Uncertainty in effective air volume (Vair) during PAS is significantly influenced by SR and KPUF/G uncertainties, often exceeding 50%.

Conclusions:

• The inherent uncertainties in KPUF/G and SR values limit the precision of air concentration measurements, particularly for PAS.
• Quantifying and reporting the uncertainty of air concentrations obtained by non-linear PAS is strongly recommended.
• Monte Carlo simulations may be necessary to adequately address the uncertainties in KPUF/G for target and depuration chemicals, which generally exceed 30%.