Ozone precursors

Unattended PAMS monitoring of ultra-volatiles using helium-free automated TD–GC with water removal

On-line monitoring of ozone precursors and other ultra-volatiles is important for understanding the formation of low-level ozone, which is harmful to health. In the USA, 59 such compounds are monitored at over 40 Photochemical Assessment Monitoring Stations (PAMS), many of which are now using new automated thermal desorption–gas chromatography (TD–GC) systems as a result of the ‘re-engineered’ PAMS stipulations that came into force in 2019. We talk to Pete Furdyna at New York State Department of Environmental Conservation (NYSDEC) about his experience using Markes’ automated equipment to meet these more stringent requirements, and in particular the need to remove airborne moisture to enable ultra-volatiles and polar species
to be monitored.

The changing requirements of the PAMS programme

For over 10 years, Pete Furdyna has been involved in monitoring volatile organic compounds at New York State Department of Environmental Conservation (NYSDEC), and so knows first-hand what a good monitoring system needs to achieve. The station he helps to run is based in New York Botanic Gardens in the Bronx, and is one of 43 Photochemical Assessment Monitoring Stations (PAMS) across the USA that measure volatiles and ultra-volatiles in urban areas, to track trends and support the development of models of low-level ozone formation, responsible for smog formation. The program has been running since 1993, but in 2019 – following a decade-long period of ‘re-engineering’ the whole PAMS scheme – those requirements changed. One of the main changes was requiring hourly VOC measurements using an automated GC setup. As at many other stations, that required a change in the equipment used at NYSDEC, says Furdyna.
Although the final decision on the equipment used was down to the individual agency, to aid decision-making the US EPA commissioned laboratory and field trials of equipment from
various suppliers – trials in which thermal desorption–gas chromatography (TD–GC) systems using Markes’ thermal  desorbers came out on top.

As a result, today Furdyna benefits from a Markes system in his lab that is able to carry out the necessary  unattended on-line measurements of everything from acetylene to undecane. The system comprises a  CIA Advantage-xr™ autosampler with a Kori-xr™ water condenser and UNITY-xr™ thermal desorber, coupled with a  dual-column GC–FID system.