Solvent extraction of Pb(II) from acid medium with zinc hexamamethylenedithiocarbamate followed by back-extraction and subsequent determination by FAAS Original Research Article

Zinc hexamethylenedithiocarbamate, Zn(HMDC)2, was used for the extraction of Pb(II) from HCl and HNO3 media into 2,6-dimethyl-4-heptanone (DIBK). The kinetic stability of Pb(HMDC)2/DIBK after extraction was found to decrease with increase in acid concentration and time, however, its stability is better in comparison with that of ammonium pyrrolidine dithiocarbamate (APDC). The half lives of Pb(HMDC)2/DIBK extracted from 10−4, 10−2, 0.1, and 1.0 mol l−1 HCl were 600, 360, 300 and 240 min, respectively. The logarithmic conditional extraction constant, log Kex′, of Pb(HMDC)2, was 5.6±0.3. Lead(II) was quantitatively extracted with 2.41×10−3 mol l−1 Zn(HMDC)2 in DIBK from 10−4 to 1 mol l−1 HCl and from 10−4 to 2 mol l−1 HNO3 solutions. The applicability of the chelating agent for the extraction of lead in real samples was confirmed by analysis of standard reference materials, the results of which were in good agreement with the recommended values. The detection limit based on three times the standard deviation of eight replicate procedural blanks was 0.07 μg l−1.