Improved Identification of Organic Markers in Ambient Particulate Matter (PM2.5) for Reliable Source Attribution

Air Monitoring, Methods, and Technology
Poster Presentation

Prepared by L. McGregor1, H. Calder2, M. Edwards3, S. Smith4, A. Parker1
1 - SepSolve Analytical, Cygnet Park, 4 Swan Court, Peterborough, Cambs, PE7 8GX, United Kingdom
2 - Markes International Ltd, Gwaun Elai Medi-Science Campus, Llantristant, CF72 8XL, United Kingdom
3 - SepSolve Analytical, 826 King Street North, Waterloo, Ontario, N2J 4G8, Canada
4 - SepSolve Analytical, Cygnet Park, 4 Swan Court, Peterborough, PE7 8GX, United Kingdom


Contact Information: lmcgregor@sepsolve.com; 01733669222

ABSTRACT

The issue of urban air quality has received increased attention in recent years due to increased awareness of the potential health risks associated with particulate matter (PM). Airborne particles with diameters <2.5 μm (so-called PM2.5) are of most concern, as long-term exposure is thought to have the biggest impact on public health.

PM2.5 consists of wide-ranging compounds from both primary emissions and secondary reaction, and drastic changes in environmental air quality during the COVID-19 pandemic mean it is now more important than ever to have accurate chemical fingerprinting and reliable source attribution.

PM2.5 is typically trapped onto quartz fibre filters and the semi-volatile organic compounds (SVOCs) are solvent extracted in a multi-step process prior to GC-MS analysis. However, sample preparation is time-consuming and the potential for error increases at each stage. In addition, solvent extraction dilutes the sample and waste disposal becomes an environmental concern in its own right.

Such limitations have led global research organisations to search for improved workflows. Direct thermal desorption (TD) of the filter offers a solution to the time-consuming sample preparation and environmental concerns. Providing simple, yet sensitive, analysis of particulate matter with increased sample security through the ability to re-collect a portion of the sample for repeat analysis.

However, chemical fingerprinting of PM2.5 remains a challenge due to sample complexity. Analysts may attempt to address this using longer columns and/or slower oven temperature ramps, but this inevitably leads to longer analysis times. In recent years, the complexity of such samples has been revealed using the improved separation of comprehensive two-dimensional GC coupled with time-of-flight mass spectrometry (GC×GC–TOF MS)

Here, we demonstrate the enhanced performance of TD-GC×GC–TOF MS by analysis of a number of real-world samples.