Mercury isolation technique

In general, methods are classified according to the isolation technique and the detection system. Most methods for the isolation/separation of organomer-cury compounds have been based on solvent extraction, differential reduction, difference calculations between total and ionic mercury, derivatization, or with paper- and thin-layer chromatography (TLC). The most common approaches to organomercury separation and detection are schematically presented in Figure 1. 

Using matrix isolation techniques, we obtained the first spectroscopic evidence for the intermediacy of the hitherto unknown silacarbonyl and silathiocarbonyl yUdes in a low temperature matrix. Irradiation of the oxasUirane (75a) in an isopentane/3-methylpentane (Ip/3-Mp) matrix at 77 K with a low-pressure mercury lamp led to the appearance of a new band at 610 nm in the UV-vis spectrum and the matrix became interestingly blue in color. This absorption band was stable at 77 K on prolonged standing. However, it immediately disappeared on brief irradiation with a Xenon lamp (X >460 nm) or when the matrix was allowed to melt. This colored species was independently generated by the reaction of dimesitylsilylene with l,l,3,3-tetramethyl-2-indanone (76a). Furthermore, irradiation of 2,2-dimesitylhexamethyltrisUane in the presence of 76a in IP/3-MP at 77 K... 

The isolation of mercury is comparatively straightforward. The most primitive method consisted simply of heating cinnabar in a fire of brushwood. The latter acted as fuel and condenser, and metallic mercury collected in the ashes. Modem techniques are of course less crude than this but the basic principle is much the same. After being crushed and concentrated by... 

Direct determination of species. With a combination of techniques (e.g. GC and AAS) several distinct organic species can be isolated and determined, e.g. organo-lead, -mercury and -tin compounds (Chau and Wong, 1983). Also the distinction of several organic and inorganic species of As (Braman et al., 1977 Andreae, 1977) and Sb (Andreae, 1983) have been reported. 

Techniques for measuring the intensity of fluorescence have been reviewed in detail elsewhere (33). Usually one uses a medium pressure mercury lamp as the light source with a Wood s glass filter which isolates mainly the intense 365 m/j. line. The fluorescence can be detected with a multiplier phototube in front of which is an appropriate filter determined... 

The main advantages of this procedure are simplicity of apparatus and technique, availability of reactants, ease of product isolation in good yield, and purity of product. The submitter has also used this method successfully for the preparation of trichloromethylmercuric chloride (from mercuric chloride), bis-(trichloromethyl) mercury (from a 2 1 ratio of sodium trichloro-acetate to mercuric chloride or mercuric acetate), and trichloromethylmercuric bromide (from mercuric bromide). 

Being based on the bacterial mercury volatilization mechanism, and exploiting advantages that offer immobilization s techniques, we have planned to remove mercury from a synthetic mercurial water using a bacterial strain that has been isolated, identified and appeared to be resistant to high mercury concentrations, compared to those reported in literature. 

Hydride generation AAS (HGAAS) and cold vapour AAS (CVAAS) are special combinations of chemical separation and enrichment with AAS. In HGAAS the analyte is transformed to a volatile hydride, stripped off by an inert gas and atomized in a quartz tube, flame-in tube etc. About ten elements (As, Se, Bi, Sb etc.) can be determined by this technique. The accuracy and detection limits depend on the proper isolation of the hydride. CVAAS is the universally acknowledged most sensitive method for determination of Hg. The generation of elemental mercury vapour is similar to the hydride generation however the quartz cell may not be heated and this gives the name of the method. 

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