A rapid method for the analysis of air toxics based on US EPA TO-15

Significance of the topic

US EPA Method TO-15 is widely used for measuring hazardous air pollutants (HAPs) in ambient air. Accurate, fast analysis of volatile organic compounds (VOCs) is critical for environmental monitoring, regulatory compliance and public health. Routine laboratories face challenges with moisture interference, canister sampling integrity and extended sample cycle times. An optimized thermal desorption–GC–MS workflow can address these issues and enhance laboratory efficiency.

Objectives and overview

This application study presents a rapid chromatographic approach to US EPA TO-15 by combining Markes International’s thermal desorption system with Thermo Fisher Scientific’s single quadrupole GC–MS. The primary goals were to assess method linearity, relative response factor (RRF) variation, method detection limits (MDLs) and precision for 60 target HAP VOCs across a calibration range of 0.5 to 50 ppb.

Methodology and instrumentation

Sample introduction utilized a CIA Advantage canister interface and UNITY-xr thermal desorber. A Kori-xr moisture management trap at –30 °C removed water vapor prior to analyte focusing, protecting column integrity. Separation was achieved on a 20 m × 0.18 mm × 1 µm TraceGOLD TG-VMS column installed on a Thermo Scientific TRACE 1310 GC. Detection was performed on an ISQ 7000 single quadrupole mass spectrometer operated in full-scan mode. Chromeleon CDS software automated eWorkflows, data acquisition and processing.

Main results and discussion

The TD–GC–MS configuration resolved all 60 HAPs in under 13 minutes. Calibration curves over 0.5–50 µg/L exhibited excellent linearity (R² > 0.995) with RRF %RSD values below 30%. MDLs determined from seven replicates at 0.5 ppb were well below regulatory requirements, demonstrating effective moisture control and absence of interfering peaks. Precision testing (seven replicates at 8 ppb) yielded %RSD values generally under 15%, comfortably meeting the TO-15 criterion of ≤ 25%.

Benefits and practical applications

• High throughput analysis with full separation and quantitation in under 13 minutes.
• Robust moisture removal via the Kori-xr trap extends column and detector lifetime.
• Sensitivity and precision meet or exceed US EPA TO-15 requirements for 60 air toxics.
• Automated Chromeleon CDS workflows enhance data consistency and operational efficiency.

Future trends and potential uses

Ongoing development of cryogen-free preconcentration and advanced moisture management is expected to further reduce maintenance and sample carryover. Next-generation GC–MS platforms with integrated automation and real-time data processing will support continuous ambient air monitoring. Coupling with cloud-based analytics and sensor networks may enable proactive air quality management in urban and industrial environments.

Conclusion

The integrated TD–GC–MS solution from Markes International and Thermo Fisher Scientific offers a rapid, robust workflow for US EPA TO-15 compliance. Effective moisture management, swift chromatographic separation and reliable mass spectrometric detection provide accurate quantitation of 60 volatile air toxics. Adoption of this method yields improved throughput, consistent performance and regulatory conformity.

References

1. US Environmental Protection Agency. Compendium of Methods for the Determination of Volatile Organic Compounds (VOCs) in Air Collected in Specially-Prepared Canisters and Analyzed by Gas Chromatography/Mass Spectrometry (GC/MS), Method TO-15, 1999.
2. Markes International. Application Note 133: Enhancing US EPA TO-15 Compliance with Cryogen-Free Ambient Air Monitoring, 2017.
3. Thermo Fisher Scientific. AppsLab Library, thermofisher.com/appslab.