Quality control for sampling of PCDD/PCDF emissions from open combustion sources

Area of Science:

• Environmental Chemistry
• Analytical Chemistry
• Air Pollution Monitoring

Background:

• Polychlorinated dibenzodioxins/dibenzofurans (PCDDs/PCDFs) are persistent organic pollutants requiring accurate air sampling methods.
• Polyurethane foam (PUF) is a common sorbent for sampling PCDD/PCDFs, but its performance under high temperature and long duration sampling is not fully understood.
• Open burning of waste, such as at military bases, can be a source of PCDD/PCDF emissions.

Purpose of the Study:

• To determine if high volume air sampling or elevated temperatures cause PCDD/PCDF loss from PUF sorbents.
• To assess the potential for analyte 'blow off' from PUF during ambient air sampling under varying conditions.

Main Methods:

• Ambient air sampling using EPA Method TO-9A with a filter/PUF/PUF series configuration to capture PCDD/PCDFs from simulated military waste emissions.
• Post-sampling analysis of a second PUF to quantify any PCDD/PCDF transfer, indicating loss from the primary sorbent.
• Laboratory evaluation of spiked PCDD/PCDF standards on PUF across a temperature range (ambient to 145°C) and sampled volumes (600 L to 2400 L) to assess analyte mobility.

Main Results:

• Less than 4.4% of initial PCDD/PCDF was lost to the second PUF during a 185-minute sampling event followed by 6 hours of ambient air sampling.
• Increased temperature and higher sampled volumes led to greater release of spiked PCDD/PCDF standards from PUF, consistent with vapor pressure effects.
• The temperature at which 1% of tetra-CDD was released decreased from 87°C to 73°C when sampled volume increased fourfold (600 L to 2400 L).

Conclusions:

• Standard ambient air sampling methods using PUF sorbents are robust and show minimal PCDD/PCDF loss even under extended sampling durations and elevated temperatures.
• The potential for analyte blow-off is influenced by compound volatility and sampling volume, with lower chlorinated dioxins/furans being more susceptible at higher temperatures and volumes.
• These findings support the reliability of PUF-based sampling for accurate environmental assessment of PCDD/PCDF contamination.