Moving Beyond TO-15: What’s New in Air Toxics Analysis?

Air Monitoring, Methods, and Technology (Session 2)
Oral Presentation

Presented by C. Widdowson
Prepared by N. Watson1, H. Martin2, H. Calder3, T. Anumol4
1 - Markes International, Inc., 2355 Gold Meadow Way, Gold River, Gold River, Sacramento, CALIFORNIA, 95670, United States
2 - Markes International, Gwaun Elai Medi-Science Campus, Llantrisant, Llantrisant, CF72 8XL, United Kingdom
3 - Markes International Ltd, Gwaun Elai Medi-Science Campus, Llantristant, No State Available, CF72 8XL, United Kingdom
4 - Agilent Technologies Inc., 2850 Centerville Road, Wilmington, DE, 19808, United States

Contact Information: [email protected]; 866-483-5684


EPA method TO-15 has dominated air analysis in the USA for 20 years, becoming the method of choice for monitoring a wide range of compounds from ambient, indoor and industrial environments. The popularity of TO-15 can largely be attributed to the adaptability of the sampling methodology and the overall sensitivity of the techniques.

In 2020 TO-15 was superseded by method TO-15a. The level of pollution in the USA has decreased significantly over 20 years but many volatile organic compounds (VOCs) are harmful at ppt levels. This success means that modern monitoring workflows must reach significantly lower limits of detection to produce meaningful data when monitoring ambient air concentrations.

It is not only in the USA where TO-15 has evolved into more analytically challenging methods, Chinese method HJ 759 adds labile sulfur compounds to TO-15, bringing odorous emission monitoring to the air toxics method. These highly reactive compounds pose an extra challenge to the analytical system, requiring a balance between the inertness required for labile sulfurs and recovery for the wide range of TO-15 targets. Further advancement from TO-15 removes canisters from the method all together moving to online, near real time instruments deployed in mobile laboratories to respond to pollution incidents.

This presentation will explore the global development of TO-15 and discuss analytical strategies to meet these new challenges. Evolving global methods share many priorities. Complex target lists and ever decreasing limits of detection must be balanced with high throughput methods and reduced cost per analysis. We will show how confident identification and quantitation, with maximum sensitivity and productivity, can be achieved using state of the art pre-concentration combined with GC– MS across a range of air monitoring methods. We will also show how the cryogen-free technology enhances our insight into air quality, complementing canister analysis with remote, on-line monitoring.