Environmental mercury analysis using a direct current discharge emission type detector.

摘要

A novel integrative air monitor to measure the organic and inorganic components of mercury has been developed. Collection and preconcentration are accomplished by using a series of sorbent tubes in sequence. A carbon hollow tube quantitatively collects all the organic Hg type compounds and is followed by a silver denuder, which collects the inorganic vapor phase fraction. Aerosols pass through carbon and silver denuders and are trapped on a gold-packed tube downstream.; Each collection tube is separately analyzed for mercury, by thermal desorption of the collected forms into a DC discharge detector. The mercury species collected on the carbon denuder retain their integrity on simultaneous thermodesorption. They are separated, before they reach the detector, by a series of inner-coated hollow tubes each having an affinity for a particular mercury compound. On desorption from the carbon denuder, the methylmercury form collects on a NaOH-coated hollow tube, Hg0 deposits on a silver hollow tube and dimethylmercury is not collected by either tube but is swept into the detector. No serious interferences which were considered have been observed in the analysis. Highly sensitive analyses can be obtained using a DC discharge emission type detector; detection limits are on the order of 5 pg.; The second part of this study involves the analysis of mercury in sediment samples. A method was developed that involves the ashing of the sample and amalgamation of the released mercury on gold. This fast technique provides the total mercury content of the sample. To obtain information as to the speciation of mercury in the sample matrix, the technique was complimented with a membrane probe method, which involves the reduction of mercury in solution to the elemental form and diffusion across a membrane. The membrane probe method was expanded to the analysis of nonlabile mercury forms, including mercury sulfide.