Mercurials, organic

Mercury. The fkst successful use of mercury as a fungicide occurred in 1913 (8). The fkst seed treatment compound developed was chloro(2-hydroxyphenyl)mercury [90-03-9] (1). Subsequentiy, a number of organic mercury derivatives having general formula RHgX have been used. 

Trace Mercury. There are a number and variety of methods and instmments to determine trace quantities of both inorganic and organic mercury ia natural or synthetic substances (19) (see also Trace and residue analysis). Literature describiag numerous techniques and trace element analysis of a myriad of mercury-containing substances is available (20). Only the most commonly used methods are mentioned hereia. 

The primary use of mercuric acetate is as a starting material for the manufacture of organic mercury compounds. 

Other organic mercurials used as antiseptics iaclude mercocresol/5 (9 )7-77-(y, acetomeroctol [584-18-9] acetoxymercuri-2-ethylhexyiphenosulfonate [1301 -13-9] and sodium2,4-dihydroxy-3,5-dihydroxymercuribenzophenone-2-sulfonate/i)(9 )(9 7-j5y (see Disinfectants and antiseptics). 

Other organic mercurials similar in chemical stmcture to chlormerodrin are meraHuride/7(94-2(9-j5y, mercaptomerin/2 (922J-< 4-/7, and mersalyl [486-67-9]. Mercury-based diuretics (qv) are no longer in use. 

Most inorganic mercury compounds have very low vapor pressures, and generally do not contribute to high mercury vapor readings. MetaUic mercury is the most potent and troublesome in this respect. Organic mercurials also contribute to mercury vapor readings, possibly by virtue of the presence of extremely small amounts of metallic mercury present as an impurity. 

The control of mercury in the effluent derived from the manufacturing processes used in the preparation of inorganic and organic mercurials is mandated bylaw in the United States. The concentrations and the total amounts vary with the industry and the location, but generally it is requited that the... 

When the mercury present in the atmosphere is primarily in the form of an organic mercury compound, it may be preferable to utilise an aqueous scmbber. This method is particularly useful for control of emissions from reactors and from dryers. For efficient and economical operation, an aqueous solution of caustic soda, sodium hypochlorite, or sodium sulfide is reckculated through the scmbber until the solution is saturated with the mercury compound. 

Problems of removal of mercury from aqueous effluents are more comphcated in plants that manufacture a variety of inorganic and organic mercury compounds it is generally best to separate the effluent streams of inorganic and organic mercurials. When phenyhnercuric acetate is precipitated from its solution in acetic acid by addition of water, the filtrate is collected and reused for the next precipitation. This type of recycling is necessary not only for economic reasons but also to minimise recovery operations. 

Methanol intoxication can cause blindness due to damage to ganglion cells in the retina. The blindness results from the accumulation of formaldehyde and formic acid, which are metabolites of methanol. Chemical compounds can also damage the visual cortex, for example, visual damage was observed among the victims of organic mercury intoxication in Japan (the fishermen of Minamata Bay). ... 

Heavy metals may also be concentrated in passage up the food chain. Other pollutants, e.g. fungicides, pesticides, biocides, polychlorinated biphenyls or organic mercury compounds, are persistent and can therefore also bioaccumulate. 

The degradation of phenylmercuric acetate to benzene, methylmercuric chloride to methane, and ethylmercuric chloride to ethane and Hg + is apparently carried out by different enzymes from the plasmid-carrying Escherichia coli strain K12 (R831) (Schottel 1978) and Pseudomonas sp. Resistance to organic mercury compounds has also been found in clinical isolates of nontuber-culous, rapidly growing mycobacteria (Steingrube et al. 1991) and can present a challenge in the clinical environment. 

Mahaffey KR, Chckner RP, Bodurow CC. 2004. Blood organic mercury and diefary mercury intake National Health and Nutrition Examination Survey, 1999 and 2000. Environ Health Perspect 112 562-570. 

Aoki H. 1970. [Environmental contamination by mercury (Hg series No. 14). 3. Inorganic and organic mercury in human hair and marine fish]. Nippon Eiseigaku Zasshi 24 556-562. 

Dansereau M, Lariviere N, Du Tremblay D, Belanger D. 1999. Reproductive performance of two generations of female semidomesticated mink fed diets containing organic mercury contaminated freshwater fish. Arch Environ Contam Toxicol 36 221-226. 

Thompson DR, Furness RW. 1989b. Comparison of the levels of total and organic mercury in seabird feathers. Mar PoUut Bull 20 557-579. 

Since the organic mercurials offer an alternative to quaternary ammonium preservatives, and since preservative efficacy of ophthalmic solutions is essential, the choice among these alternatives should be based on a benefit-to-risk analysis as long as a ban is not imposed on the use of these organometallic preservatives. 

Ishihara, N. and Urushiyana, K., Longitudinal study of workers exposed to mercury vapor at low concentration Time course of inorganic and organic mercury concentration in urine, Toxicology and Applied Pharmacology, 155, 161-168, 1994. 

These workers distinguished between inorganic mercury obtained by direct analysis on the sample as received, and organic mercury (the difference between total mercury obtained upon ultraviolet irradiation of the sample and inorganic mercury). 

The interest in mercury contamination, and particularly in the organic mercury compounds, is a direct reflection of the toxicity of these compounds to man. Some idea of the proliferation of work can be derived from the reviews of Krenkel [25], Robinson and Scott [26] (460 references), and Uthe and Armstrong [27] (283 references). 

Most of the methods of analysis for mercury actually measure inorganic mercury to measure either organic or total mercury by such methods, it is necessary to decompose any organic mercury compounds present. This decomposition can be effected by ultraviolet irradiation of the samples. Systems of this sort have been described [46-48]. Since as much as 50% of the mercury maybe present in organic form [46] the differentiation between inorganic and organic mercury can be of considerable importance. 

Graphite furnace atomic absorption spectrophotometry has been used for the determination down to 5 ng/1 inorganic and organic mercury in seawater [61]. The method used a preliminary preconcentration of mercury using the ammonium pyrrolidine dithiocarbamate-chloroform system. A recovery of 85 - 86% of mercury was reproducibly obtained in the first chloroform extract and consequently it was possible to calibrate the method on this basis. A standard deviation of 2.6% was obtained on a seawater sample containing 529 ng/1 mercury. 

The high sensitivity and selectivity of some gas chromatographic detectors are used to advantage in the measurement of organic mercury compounds. In the simplest approach, methyl mercury is extracted from seawater and converted to the iodide for electron capture gas chromatography [74],... 

A number of analytical methods for the separation of organic mercury compounds use an initial extraction of the organic materials with an organic solvent. Klisenko and Shmigidina [83] then converted both the inorganic mercury held in the aqueous fraction and the organic mercury in the chloroform extract to dithizonate, separated the components on chromatographic columns, and determined the concentration of the various fractions by comparison with reference standards. This method is semi-quantitative at best. 

Differentiation of inorganic and organic mercury can be achieved in a number of different ways, many of which depend upon the reduction and vapourisation of the inorganic mercury, followed by reduction [84] or oxidation [85,86] of the organic mercury compounds, and a final measurement by atomic absorption or mass spectrometry. Similar methods of separation of the inorganic and organic components are used in the pretreatment of samples where the final analysis for mercury is to be made by neutron activation analysis [87,88]. 

Ke and Thibert [90] have described a kinetic microdetermination of down to 0.05 xg/l of inorganic and organic mercury in river water and seawater. Mercury is determined by use of the iodide-catalysed reaction between CeIV and As111, which is followed spectrophotometrically at 273 nm. 

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