Determination of stability constants of mercury(II) by garlic organosulfur ligands with differential pulse voltammetry

Abstract

In this work, interactions of mercury with di allyl disulfide (DADS), dimethyl disulfide (DMDS), and diallyl sulfide (DAS) were studied by differential pulse voltammetry. A thorough investigation was carried out on the complexation of mercury(II) by the garlic organosulfur ligands DADS, DMDS, and DAS at different steps. The optimal measurement conditions were conducted to determine the corresponding stability constants. The determination of stability constants of the labile mercury(II) with DADS, DMDS, and DAS complexes were based on the DE Ford-Hume methodology (equation) that calculated from the dependence of the shift of mercury(II) peak potential upon addition of the DADS, DMDA and DAS ligands separately. The results of this study provide evidence of the formation of 1:1 complexes between mercury(II) and DADS, DMDS, and DAS with the computed logβ1 values of the formation constants: (DADS): log β1\u2009=\u20095.32\u2009±\u20090.46, (DMDS): log β1\u2009=\u20095.40\u2009±\u20090.38, (DAS): log β1\u2009=\u20094.61\u2009±\u20090.5 respectively.