Location: Soil, Water & Air Resources ResearchTitle: Performance of commercial non-methane hydrocarbon analyzers in monitoring polar volatile organic compounds Author
Submitted to: Journal of Air and Waste Management Association
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/6/2013
Publication Date: 10/15/2013
Citation: Trabue, S.L., Scoggin, K.D., Li, H., Burns, R., Xin, H., Mcconnell, L.L., Gates, R., Hasson, A., Ogunjemiyo, S., Hatfield, J.L., Turner, A. 2013. Performance of commercial non-methane hydrocarbon analyzers in monitoring polar volatile organic compounds. Journal of Air and Waste Management Association. 63:1163-1171. Interpretive Summary: Quantifying non-methane hydrocarbons (NMHC) from animal feeding operations is challenged due in part to diversity and chemical properties of compounds and changing nature of their emissions. There are a number of commercial instruments designed for quantifying NMHC giving researchers both an affordable and easy means at quantifying volatile organic compounds (VOCs) from animal feeding operations. Three different types of NMHC analyzers were tested in the laboratory and in the field against both known standards and chemically determined standard methods. Laboratory experiments showed that the commercial instruments accurate measured non-polar compounds, but polar compounds were being underreported by NMHC analyzers with known standards. Field experiments showed that laboratory instruments underreported true concentration in the field due to the fact that the most abundant NMHC associated with animal feeding operations were polar in nature. This report recommends not using NMHC analyzers for quantifying VOCs at animal feeding operations. The information in this report can be used by scientists, engineers, and regulatory officials involved with emissions of volatile organic compounds from animal feeding operations because of the improved ability to quantify emissions correctly.
Technical Abstract: Quantifying non-methane hydrocarbons (NMHC) from animal feeding operations (AFOs) is challenging due to the broad spectrum of compounds and the polar nature of the most abundant compounds. The purpose of this study was to determine the performance of commercial NMHC analyzers for measuring volatile organic compounds (VOCs) commonly emitted from AFOs. Three different NMHC analyzers were tested for response to laboratory generated VOCs, and two were tested in the field at a commercial poultry facility. Previous measurements identified the most commonly detected VOCs at the facility as acetic acid, 2,3-butanedione, methanol, acetone, and ethanol. The NMHC analyzers tested included gas chromatography/flame ionization detector (GC/FID), photoacoustic infrared (PA-IR) and photoionization detector (PID). The GC/FID NHHC analyzer was linear in response to non-polar compounds, but detector response to polar oxygenated compounds were lower than expected due to poor peak shape on the column. Better agreement between expected and measured values was achieved by correcting for both detector response and chromatography. The PA-IR NMHC instrument responded well to the calibration standard (propane). However, the PA-IR response to other compound classes were lower and varied between compounds in similar compound classes. The PID responded poorly to many of the most abundant VOCs at AFOs, and it underreported alcohols by >70%. In the field monitoring study, total NMHC concentrations were calculated from the speciation of individual compounds using EPA Methods TO-15 and TO-17 and were compared to results from NMHC analyzers. NMHC GC/FID values were greater than the values calculated from the individual compound measurements. This indicated the presence of hydrocarbons not measured with TO-15 or TO-17 such as propane. The PA-IR response was variable, but it was always lower than the GC/FID response. Results suggest that improved approaches are needed to accurately determine the VOC profile and NMHC emission rates from AFOs.