A Polarographic Study of the Cadmium Thiocyanate Complexes¹

Voltammetry as a Virtual Potentiometric Sensor in Modeling of a Metal‐Ligand System and Refinement of Stability Constants. Part 1. Polarographic and Glass Electrode Potentiometric Study of a Dynamic Cd‐Glycine System

“…The analysis of the shift as a function of an excess of added ligand at fixed pH started over 60 years ago with Lingane equation [6] allowing an evaluation of a stability constant for a single complex ML q present in a solution when a fully dynamic M-L system and reversible electrochemical process were observed. A significant progress was made by DeFord and Hume [7,8] who have modified the Lingane equation to the form that allowed evaluation of stability constants of several complexes formed in consecutive fashion with exactly the same experimental conditions as it was described by Lingen, e.g., titration of a metal ion solution by ligand at fixed pH with strict requirement of full reversibility of electrochemical signal recorded on a dynamic (labile) metal-ligand system. Schaap and McMasters [9] extended the DeFord and Hume methodology to systems involving two competing ligands.…”

Modelling of Cadmium(II) Species Formed With N,N′-Bis(2-pyridylmethyl)-1,2-diaminoethane and Optimisation of Stability Constants by the Use of Polarographic Complex Formation Curves for Labile Metal–Ligand Systems

“…Especially the fact that the complex M(HL) could be accounted for when the described polarographic curve fitting procedure was used indicates the power and sensitivity of this approach. It is obvious that the conventional polarographic techniques of speciation [16][17][18] would be of no use in this case.…”

Elucidation of Abnormal Potential Responses of Cation-Selective Electrodes with Solid-State Membranes to Aqueous Solutions of CuCl2 and CdI2

“…Many ion-pair (or complex) formation constants of divalent metal salts (MX 2 ) in water (w) have been determined so far [1][2][3][4]. In the course of potentiometric determination of these constants for CdI 2 and CdBr 2 in a bulk w by using a commercial Cd 2+ electrode with a solid-state membrane [4], plots of the emf versus log 2(*[CdX 2 ] t ) gave peaks, where *[CdX 2 ] t (= *[Cd] t ) denotes a total concentration of CdX 2 in the bulk w. Especially, as shown in Figure 1 of the previous paper [4], a slope of the plot for the CdI 2 system was positive in the lower range of log 2(*[CdI 2 ] t ), while it was negative in its higher range.…”