Gas-phase analysis of trimethylamine, propionic and butyric acids, and sulfur compounds using solid-phase microextraction

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. 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 certified gas standards. A 75-μm carboxen-poly(dimethylsiloxane) (Car-PDMS) coating was used for trimethylamine (TMA), carbon disulfide (CS₂), dimethylsulfide (DMS), and dimethyl disulfide (DMDS), and an 85-μm polyacrylate coating was used for propionic acid (PA) and butyric acid (BA). Using a 1-h 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 signal was observed for all analytes under flow conditions, as compared to static conditions, and the porous nature of the Car-PDMS coating appears to increase the time needed for analytes to reach equilibrium under flow conditions.