Submitted to: Analytical Chemistry
Publication Type: Peer reviewed journal
Publication Acceptance Date: 11/9/2001
Publication Date: 3/1/2002
Citation: Kim, H., Nochetto, C., McConnell, L.L. 2002. Gas phase analysis of trimethylamine, proprionic acid and butyric acid, and sulfur compounds using solid phase microextraction. Analytical Chemistry. 74:1054-1060. Interpretive Summary: Manure generated by large animal farms can create odor problems for neighboring residents. Wastewater treatment plants also have problems with odors. States and municipalities are developing new regulations to control odors. Unfortunately the technology to reliably and objectively analyze odorous gases is not available. This research project was designed to develop a handy method to characterize and measures the chemicals that cause odors. We used a commercially available device called solid phase microextraction or SPME. Results of this study indicate that SPME can be a powerful tool for measuring low levels of the reactive gases that cause an odor response in humans. Further experiments are needed to calibrate the SPME fiber coatings under a range of temperature, humidity and flow conditions so that accurate concentration measurements can be made under real world conditions.
Technical Abstract: Complaints due to odors are an important problem for the wastewater, composting and animal agriculture industries. Accurate, objective measurement techniques are needed to monitor emissions, to develop new waste handling procedures, and to reduce the production of these volatile gases. While olfactometry methods reflect actual human response to odors, they do not provide information on all the chemical components of a gas mixture. Solid phase microextraction was investigated as a technique for the determination of representative odorous gases. A flow-through Teflon chamber was used to expose the fibers to a certified gas standard. A 75 mm Carboxen- Polydimethylsiloxane (Car-PDMS) coating was used for trimethylamine (TMA), carbon disulfide (CS2), dimethylsulide (DMS) and dimethyldisulfide (DMDS), and an 85 mm polyacrylate coating was used for propionic acid (PA) and butyric acid (BA). Using a 1-hour fiber exposure time and a flow rate through the chamber of 72 ml/min, method detection limits were 2.38, 0.074, 0.150, 0.063, 1.85, and 1.32 ppbv for TMA, DMS, CS2, DMDS, PA, and BA, respectively. Enhanced detector response was observed for all analytes under flow conditions compared to static, and the porous nature of the Car-PDMS coating appears to increase the time needed for analytes to reach equlibrium under flow conditions.