Submitted to: Journal of Environmental Quality
Publication Type: Peer reviewed journal
Publication Acceptance Date: 6/30/2006
Publication Date: 12/1/2006
Citation: Miller, D.N., Woodbury, B.L. 2006. A solid-phase microextraction chamber method for analysis of feces and manures volatiles. Journal of Environmental Quality 35:2383-2394 Interpretive Summary: A general protocol was developed to compare the relative emissions of volatile organic compounds from feces. The solid phase microextraction-flux chamber technique was robust and provided unique insights into the type and general magnitude of volatile organic compound emissions that emanate from feces from different animal species fed differing diets. Initial application of the technique illustrated the need for careful preservation of fecal samples (freezing) to ensure representative emissions measurements in the laboratory. A broad survey of emission from fecal samples obtained from cattle and swine fed a variety of diets identified significant differences in the total emission and the emission of specific odor compound classes from fresh and incubated samples. An emissions model unique to our instrument and based upon the results of these studies was developed using easily measured fecal parameters and shows great promise for future field application.
Technical Abstract: Odors from livestock operations are a complex mixture of volatile carbon, sulfur, and nitrogen compounds. Currently, detailed volatiles analysis is both time consuming and requires specialized equipment and methods. This work describes a new method that utilizes a dynamic flux chamber, solid-phase microextraction (SPME), and gas chromatography-mass spectroscopy (GC-MS) to describe and compare the odorous compounds emitted from cattle and swine feces. Evaluation of method parameters produced a protocol for comparing relative emissions based upon fixed sample temperature (20°C) and exposed surface area (523 cm2), air flow rates (1 L/min), SPME exposure time (5 min), and chamber cleaning procedures (70% ethanol rinse and drying for 30 min at 105°C) to minimize cross-contamination between samples. A variety of volatile organic compounds (VOCs) including alcohols, volatile fatty acids, aromatic ring compounds, ketones, esters, and sulfides were routinely detected and the relative emissions from fresh and incubated (37°C overnight) swine and cattle feces were compared as a measure of potential to produce odorants during manure storage. Differences in the types and relative quantities of volatiles emitted were detected when animal species (cattle or swine), diet, fecal incubation, or sample storage conditions (20°, 4°, or -20°C) were varied.