Sampling and analysis of flue gases from a plasma incinerator

A system is described for monitoring flue gases from a plasma incinerator for polychlorinated biphenyls (PCBs), polychlorinated dibenzodioxins and polychlorinated dibenzofurans. The system is composed of three basic units: sampler/preconcentrator, gas chromatograph and mass-selective detector. The sampler operates by solid sorbent trapping and thermal desorption. The use of two adsorbers allows sampling at a high flow rate (～1 1 min^?1) and subsequent capillary gas chromatographic analysis without the need for cold traps. A sample trapped on the first adsorber is thermally desorbed and transferred by a carrier stream of 40 cm³ min^?1 to a second smaller adsorber and retrapped. It is then thermally desorbed and injected into the capillary column by a carrier gas at an appropriate flow rate. A sequential valve-minder activates the electric actuators of the two six-port valves used in the design and also controls the power required for heating the adsorbers. Operation of the sampler is automated and is initiated by a single push-button switch. In simulation, the system allowed the separation of the major compounds of interest from possible interferences in <15 min and afforded unambiguous identification of the hazardous compounds and their quantification. For a sample volume of 20 1, the minimum detectable concentration of PCBs is 25–50 ng m^?3.