Study of the Hg2+ binding with chelation therapy agents by differential pulse voltammetry on rotating Au-disk electrode and electrospray ionization mass-spectrometry

A recently proposed electroanalytical method, using differential pulse voltammetry (DPV) on the rotating Au-disk electrode, and electrospray ionization mass-spectrometry (ESI-MS) has been applied to study the binding of the pharmaceutical chelating agents meso-2,3-dimercaptosuccinic acid (DMSA), sodium 2,3-dimercaptopropanesulfate (DMPS) and d-penicillamine (d-Pen) with Hg2+. From the use of voltammetric titrations it was possible to obtain a detailed picture of the complexation processes at concentrations much lower than in previous studies. Predominant species were Hg(Pen)2, Hg2(DMSA)2 and Hg(DMPS)2. For Pen, Hg(Pen) was also deduced from DPV data, while Hg2(Pen)4 from ESI-MS. For DMSA and DMPS, Hg2L species were detected by DPV, and Hg2L3, Hg3L3 as well as Hg2(DMPS)2 and Hg(DMSA)2 by ESI-MS. When possible, DPV data were analyzed by multivariate curve resolution with alternating least squares (MCR–ALS).