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Transalkylierung Pb/Hg

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Transalkylierung Pb/Hg

Although organolead as a gasoline additive is banned in most countries, contamination by organolead compounds is still present. Little is known about transformation reactions of organolead compounds and especially transalkylation reactions withother metals. Laboratory experiments to clarify transalkylation reactions between organolead and inorganic mercury, and investigations of sites, where organolead compounds were emitted, are reported. Under laboratory conditions, inorganic mercury is ethylated to ethylmercury+ in presence of tetraethyllead. These transalkylations take place very fast and almost completely.

In soil samples from an industrial site contaminated with organolead compounds and inorganic mercury, EtHg+ was clearly identified in high concentrations (up to 46 mg Hg/kg dw). Furthermore, methylmercury+ was found in concentrations up to 27 mg Hg/kg dw. It is the first time that a transethylation of an organolead compound to an organomercurial compound in the environment is reported. It must be assumed that this tranalkylation takes place at sites where organolead compounds occur and Hg2+ is available. Thus, it will be necessary to assess the risk of these sites.

Compound Method Recovery
from water
from soil
Methyl-Hg+ HPLC-AFS 97 ± 3 90 ± 8.6
Ethyl-Hg+ HPLC-AFS 97 ± 2 89 ± 11
Diethyl-Pb GC-AED 98 ± 2  
Triethyl-Pb GC-AED 94 ± 4  
Tetraethyl-Pb GC-AED 95 ± 4  
(taken from: Fresenius J Anal Chem (2000) 366:470-475)


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