Electrochemical reduction of the trimethyllead(IV) cation in seawater

Complexation of trialkyllead with diethyldithiocarbamate

“…Peak I1 (at the potential of -0.86 V) probably corresponds to the cathodic wave of (CH,),PbDDC, as a similar potential value has been found for the reduction of Pb(DDC)* [27]. Peak I11 (at the potential of -1.3 V) is due to the second reduction process of (CH,),Pb+, which is reducing according to scheme [28] (CH,),Pb+ + e-+ (CH,),Pb (first step) (12) (CHJ3Pb + 3 Hgo+ W H g ) + 3 CH& (13) (CH,)Hg + e--CH,Hg-(second step) (14)…”

Examination of interferences in the stripping voltammetric determination of trimethyllead in seawater by polarography and mercury-199 and lead-207 nuclear magnetic resonance spectrometry

“…Figure 2a shows a differential pulse polarogram (DPP) for the reduction of 1 X 10" M [(CH3)3Pb]+ in seawater in the absence of Hg(II) ions. Two reduction peaks, I and II, with peak potentials at -0.72 V and -1.23 V were observed, corresponding to the electrode processes given in eq 1 and 2, respectively (20). The complex nature of these electrode processes is shown in ref 20 [(CH3)3Pb]+ + e-v-(CH3)3Pb• + 3Hg -Pb + 3CHsHg.…”

“…Two reduction peaks, I and II, with peak potentials at -0.72 V and -1.23 V were observed, corresponding to the electrode processes given in eq 1 and 2, respectively (20). The complex nature of these electrode processes is shown in ref 20 [(CH3)3Pb]+ + e-v-(CH3)3Pb• + 3Hg -Pb + 3CHsHg. (ads) (1) 3CH3Hg.…”

“…In the absence of exchange reactions with deliberately added Hg(II), it may be possible to use a mercury electrode. However, a recent detailed investigation (20) reduction of the trimethyllead cation in seawater at the dropping mercury electrode suggests that transalkylation reactions occurring at the electrode surface may invalidate ASV data at a hanging mercury drop electrode (HMDE).…”

Application of Polarographic and Voltammetric Techniques in Environmental Analysis

“…An example of special interest is the stripping voltammetric determination of lead species in seawater after preceding membrane filtration. The polarographic behaviour of lead(II) and trimethyllead(IV) is different, so that with different deposition potentials in anodic stripping voltammetry, a differential determination of the species is possible (Bond et al 1983) REDOX STATE Electrochemical methods can, however, be sucessfully applied to the determination of elements at different oxidation states.…”