Determination of Ru (III) Metal-ions in Solution at Trace Level by Ethanethioic Acid (ETA) as Ligand by Amperometric Method

This new method of trace analysis Ru(III) metal ions by amperometric titrations with the help of organic ligand ethanethiol acid (ETA) by using dropping mercury electrode (d.m.e) Vs S.C.E is reported in the new medium consisting of supporting electrolyte 2.0 M RbCl in 7% acetic acid. The cathodic reduction of Ru (III) occurs in two stages in this medium and has been reported in the literature. The organo-sulfur ligand ETA was also found to give its characteristic reversible, one-electron anodic wave with a Half-Wave Potential of -0.174V. The ligand ETA is used as a titrant in the amperometric titrations, carried out only at some constant voltage (here,- 0.05 V) which falls in the common limiting region of the ligand ETA as well as 1st cathodic wave of metal ions of Ru (III). Though, no indication of chemical reaction was observed between these two species not indicated, the basis of this new titrimetric method seems to be the current compensation phenomenon (the beauty of amperometric). Ru (III): ETA null point molar ratio is 1:0.66 and Ru (III) solutions up to 4 ppm can be estimated with a fair degree of accuracy. The study of various interfering cations and anions is also reported in this new method.