Methylmercury derivatives

Formation of these dinuclear mercury derivatives is accompanied by a red shift of the absorbance of the bis(alk-ynyl) backbone. For example, conversion of 2,7-bis(alkynyl)fluorene into the corresponding bis(methylmercury) derivative 50 leads to a shift of the main absorption band of the bis(alkynyl) backbone from 505 to 567 nm. Similar results have been obtained for 51-56.67 68... 

Direct mercuration of alkynes has also been achieved. " The interest in mercury alkynyls stems from their documented applications in the rapid separation and detection of toxic organomercurials (particularly, methylmercury derivatives). Upon reaction with alkynes, samples containing methylmercury salts yield Hg(C=CR)2 or Hg(Me)(C=CR) species that can then be analyzed using chromatographic techniques. 

CYANO(METHYLMERCURI)GUANIDINE GUANIDINE, CYANO-, METHYLMERCURY deriv. MEMA METHYLMERCURIC CYANOGUANIDINE xMETHTL-MERCURIC DICYANDIAMIDE METHYLMERCURY DICYANDIAMIDE METHYLMERKURIDIKYANDI-AMID MMD MORSODREN MORTON EP-227 O MORTON SOIL DRENCH MORTON SOIDDRENCH-C... 

Methylmercury derivatives are the most toxic form of the element. Because they are organometallics they will dissolve in fatty tissue in animals and accumulate. Most of the mercury present in humans is in the form of methylmercury, formed in rivers by microorganisms which convert Hg + into CHaHg and (01-13)2 Hg. Fish absorb methylmercury through their gills and humans eat the fish. 

Latif MA, Bodaly RA, Johnston TA, Fudge RJP. 2001. Effects of environmental and maternally derived methylmercury on the embryonic and larval stages of walleye (Stizoste-dion vitreum). Environ Pollut 111 139-148. 

The runoff export was about 0.03 g/ha of Hgt per year. This value lies within the range of 0.008 to 0.059 g Hg/ha/yr, derived from a number of catchment studies in Sweden. The output of methylmercury from catchment area was 0.0015 g/ha/yr of Hg. This is substantially lower than the input to the catchment. There appears to be an ongoing net accumulation of Hgm in the terrestrial ecosystems, similar to the pattern previously shown for the total mercury. 

This work suggests that the application of laboratory-derived results directly to natural conditions could, in these cases, be misleading analytical results for day ten if extrapolated directly might lead to the conclusion that natural methylmercury levels and rates of methylation are much greater than in fact they really are. Work in this area with model or laboratory systems needs to be interpreted with particular caution. 

Stern, A.H. 1997. Estimation of the interindividual variability in the one-compartment pharmacokinetic model for methylmercury Implications for the derivation of a reference dose. Regul. Toxicol. Pharmacol. 25(3) 277-288. 

A technique for the determination of methylmercury in aqueous samples (natural and seawater) involved the conversion of methylmercury to gaseous methyl-ethylmercury by reaction with sodium tetraethylborate (Bloom, 1989 Bloom and Watras, 1989). The volatile derivative was purged from the solution and concentrated on a graphitic column at room temperature. The derivative was thermally desorbed from the column, and then analysed by cryogenic gas chromatography with cold vapour atomic fluorescence detection. In addition to methylmercury, labile Hg11 species could be determined (as diethylmercury) as well as dimethylmercury (which is not ethylated). The detection limit for... 

The formation of butyl derivatives of methylmercury and ethylmercury was studied as a means of providing stable, volatile derivatives for the gas chromatographic determination of these compounds (Quimby and Sullivan, 1990). The resulting dialkylmercury species were separated satisfactorily on a capillary... 

The key decision is then whether the acceptable body burden in the target species is exceeded. Canada has derived Tissue Residue (i.e., body burden) Guidelines for the Protection of Wildlife Consumers of Aquatic Biota for several substances (e.g., DDT, methylmercury, PCBs), and the EU WFD permits the establishment for some substances of a body-burden EQS recalculated as an equivalent concentration in water (Lepper 2005), but there are few other approaches of this type. As indicated,... 

The crystal structures of several mercury bis(xanthates),267,268 and organomercury derivatives, including methylmercury xanthates, MeHg(S2COR) and their supramolecular self-assembly,269 and phenylmercury xanthates, PhHg(S2COR) (R = Me, Pr1,270 Et,271 have been reported. 

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