Polarography As A Measure Of Ionic Environment

The present work is a polarographic study of the alkali metals and selected first row transition metals in DMSO (dimethylsulfoxide) with tetraethylammonium perchlorate as a supporting electrolyte. DMSO was chosen as a solvent because of its interesting solvent and complexing properties. Tetraethylammonium perchlorate was chosen as a supporting electrolyte because of its lack of complex forming tendencies and because of the wide range of voltages available for polarographic investigation before the supporting electrolyte ions react electrochemically. One of the problems, particularly in nonaqueous polarography, is the low conductivity of the solutions leading to high cell resistance. As current flows through the cell, additional voltage must be applied to overcome the “I R” voltage drop in the cell. By measuring the cell resistance while the polargram is being run and knowing the current flowing, one can correct the half-wave potentials, although this becomes rather tedious where large numbers of polarograms are to be taken. A more elegant approach to the problem is the use of the three-electrode polarographic cell and a controlled potential polarograph similar to the one developed by Kelley, Fisher, and Jones (26). A description of an instrument of this type that was used in all of the work reported in this paper is given later in the work