Trace Analysis of Heavy Metals with Two New Disodium Bisdithiocarbamates

Two chelating reagents, disodium N,N′‐dibenzylethylenebisdithiocarbamate 1 and disodium piperazinebisdithiocarbamate 2, were synthesized and used to preconcentrate trace metals in aqueous samples. For analysis of Cu(II) using a UV‐vis spectrometer, Beer's law was obeyed from 5.0 μg L −1 to 6.0 mg L −1 for reagent 1, and from 0.2 mg L −1 to 6.0mg L −1 for reagent. 2. The chelation ratio for reagent 1 to Cu(II) was determined to be 1:1, with a formation constant 1.0 × 10 9 M −l . The dependence of extraction and extraction efficiency of reagent 1 on pH was also studied with an atomic absorption spectrometer for nine heavy‐metal ions‐Cu(II), Fe(III), Pb(II), Co(II), Cr(VI), Ni(II), Zn(II), Mn(II) and Cd(II). Except Cr(VI) and Mn(II), the recovery yields of the other seven metal ions were almost quantitative at pH = 4 − 6. The recovery was 82% for Cr(VI) at pH = 4 − 5, and 52% for Mn(II) at pH = 6 − 7.