US EPA Method 327 defines a procedure for the canister-based monitoring of volatile organic hazardous air pollutants (oHAPs) from industrial and fenceline areas.
What’s involved in US EPA 327?
US EPA Method 327 emerged as part of efforts to control emissions from industries that produce or handle oHAPs.
The method provides guidelines for sampling whole-air from industrial or fenceline areas using specially prepared canisters over a 24-hour period. Once collected, the canisters are transported to a laboratory, where they undergo analysis using thermal desorption (TD) preconcentration and gas chromatography coupled with mass spectrometry (GC–MS). The use of TD significantly improves performance for the analysis of ethylene oxide and vinyl chloride, offering low-ppt detection limits and enhanced sample throughput.
Method 327 is one of the key measurement techniques facilities can adopt to meet the new compliance requirements of the Hazardous Organic National Emission Standards (HON rule), which was updated in April 2024. The updates aim to lower the risks from air toxics to people living near industrial sites, by requiring facilities to implement tighter emission controls, improve flare efficiency, and ultimately to monitor air toxics at fencelines.
Compounds monitored under US EPA Method 327
The introduction of Method 327 was driven by the need to monitor:
- Ethylene oxide, identified by the US EPA as a critical health risk and a significant driver of cancer risk. Ethylene oxide is challenging to measure due to its low response in mass spectrometry and frequent presence in canister backgrounds.
- Vinyl chloride, a known carcinogen, particularly associated with liver cancers such as hepatic angiosarcoma.
Complying with US EPA Method 327
To successfully implement Method 327, facilities need fast, reliable, cost-effective analytical instruments that can provide accurate and consistent results.
Markes’ UNITY–CIA Advantage-xr, combined with the Kori-xr water-removal module, offers the following advantages:
- Fast analysis – Analysis of vinyl chloride and ethylene oxide is possible with a 3-minute GC run; other compounds (for example the full list of compounds required by US EPA Method TO-15A) can be analysed within 19 minutes.
- Reliability – Efficient and selective water removal with the Kori-xr water-removal module results in less instrument downtime, greater retention time repeatability, and more confidence in results.
- Sensitivity – Method detection limits below 10 ppt from a 500 mL sample can be achieved, with the ability to take up to 1.5 L samples of ethylene oxide when required to lower detection limits.
- Cost saving – The electrically-operated Peltier coolers incorporated into Markes’ systems allow analysis of compounds as volatile as C2 hydrocarbons, without the inconvenience of cryogen and the associated risk of flow-path ice blockages.
- Sample flexibility – The backflushed focusing trap enables flexible sample volumes to be taken.
- Future-proof operation – A tube autosampler can be added to the instrument configuration, to allow analysis using tube-based methods such as US EPA Method 325. This provides a system able to accommodate a diverse range of applications, and a wider range of compounds regulated under the HON rule (including benzene and chloroprene).
For more on complying with Method 327 using the UNITY–CIA Advantage-xr, read Markes' Application Note 176.
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Questions about US EPA Method 327?
Our team is here to provide expert advice on air monitoring, and guidance on method setup, system configuration, and troubleshooting for Method 327, to ensure compliance and data quality.
