Gas chromatographic-mass spectrometric determination of sulfolane in wetland vegetation exposed to sour gas-contaminated groundwater.

Described is a GC-MS method for the determination of the levels of sulfolane (tetrahydrothiophene 1,1-dioxide, C4H8O2S; a water miscible chemical used in the sweetening of sour gas) in wetland vegetation (roots, shoots, berries, seeds, grasses, and leaves). The technique was developed to provide positive detection of sulfolane in a variety of wetland vegetation and to determine the extent to which sulfolane may translocate within the plants. Vegetation samples collected at a sour gas processing facility were extracted using a two-stage process which utilized a back extraction of a water extract with toluene. The main advantages of this procedure were: good extraction efficiency (recovery of 80+/-12%), exclusion of most of the highly polar co-extractives during the toluene back extraction step, and a final extract well suited to routine GC-MS selected ion monitoring of sulfolane with a detection limit of 90 ng g(-1) (wet mass). In general, the method was rugged, based on a study period of 18 months in which over 175 runs were conducted.

Health risks of "dioxins": a review of environmental and toxicological considerations.

Polychlorinated dibenzo-p-dioxins are the focus of great public concern because of the extreme toxicity of some congeners in animal studies, their apparent ubiquity in our food and the environment, and their involvement in some well-publicized environmental contamination incidents. This review summarizes and discusses some environmental and toxicological aspects of dioxins, with major focus on the toxicity of 2,3,7,8-tetrachlorodibenzo-p-dioxin (2,3,7,8-TCDD). In many animals, 2,3,7,8-TCDD is extremely toxic, but species differences are evident. Humans appear more resistant to the effects of 2,3,7,8-TCDD than most animal species tested. However, since human exposure has usually occurred to a mixture of chemicals, of which 2,3,7,8-TCDD is only 1 component, it is often difficult to clearly relate effects in humans to exposure to this compound. So far, it appears that chloracne is the only proven consequence of human exposure to 2,3,7,8-TCDD. Attempts to estimate the carcinogenic risk from 2,3,7,8-TCDD in humans have failed to provide reliable evidence. However, the International Agency for Research on Cancer has classified this compound as a possible human carcinogen based on animal studies. Whether 2,3,7,8-TCDD, in small quantities, poses any significant health risk is still debatable. It appears prudent to limit human exposure to this compound as much as possible.

Model studies of polychlorinated dibenzo-p-dioxin formation during municipal refuse incineration.

Toxic chlorinated dibenzo-p-dioxins are known to be formed in incinerators that burn municipal refuse. These compounds were synthesized by surface-catalyzed reactions on fly ash particulates taken from incinerators. Dioxins were produced catalytically from chlorinated phenol precursors, from non-chlorinated compounds that were chemically dissimilar to dioxins, and from reaction of phenol with inorganic chlorides. The relative amounts of dioxins formed from [13C6]pentachlorophenol with different fly ashes that had been cleaned of all organic compounds corresponded well with those amounts originally found on the samples as received from the incinerators. The optimum temperature range for the formation of dioxins from pentachlorophenol was 250 degrees to 350 degrees C.

Mechanism of formation of polychlorinated dibenzo-p-dioxins produced on municipal incinerator flyash from reactions of chlorinated phenols.

All incinerators burning municipal waste produce chlorinated dioxins. The mechanism by which these compounds are formed is unknown. Experiments were performed that show these compounds can be produced from known precursors by surface catalysed reactions on the flyash particulates present in the incineration process. A full range of the tetra- through octachlorinated dibenzo-p-dioxins were produced from 13C-labelled pentachlorophenol and two trichlorophenols on the surface of flyash from an Ontario municipal incinerator that had been previously freed from organic material. A simple flow-tube apparatus at 300 degrees C under a 10-ml/min nitrogen flow was used for the experiments. The use of 13C-labelled pentachlorophenol gave a direct measure of the extent of the catalytic reactivity of the flyash surface. Much lower amounts of chlorinated dioxins were produced in similar experiments with flyash from a modern Japanese incinerator whose effluents are normally extremely low in these compounds. Only small amounts of octachlorodioxin, the thermal condensation product expected, were formed using ground firebrick or an empty flow-tube for the reactive surface. These results indicate that the flyash surface has constituents and properties that promote the production of chlorinated dioxins from chlorinated phenols and support the catalyzed surface reaction mechanism previously proposed.