A Novel Approach to Monitoring of the Diffusion Junction Potential in Speciation Studies by Polarography Under very Acidic Conditions. Part I: The Reversible Cd(II)-Picolinic Acid System

作者：Billing Caren^*; Cukrowski Ignacy; Jordan Blake

来源：Electroanalysis, 2013, 25(9): 2221-2230.

DOI：10.1002/elan.201300256

• Cadmium
• Diffusion junction potential
• Formation constants
• Picolinic acid
• Voltammetry

A new polarographic procedure has been developed for the study of metal-ligand equilibria at pH%26lt;2 by applying an in situ monitoring of the diffusion junction potential by introducing a noncomplexing witness metal ion, Tl(I). As a case study, this procedure was applied to the Cd(II)-picolinic acid (pyridine-2-carboxylic acid) system; DCTAST polarography was employed at 25 degrees C and ionic strength of 0.25-0.5M (H,Na)NO3. Log values of 4.26 +/- 0.03, 7.86 +/- 0.11 and 10.47 +/- 0.12 were obtained for the ML, ML2 and ML3 complexes, respectively, and compare well to literature values. The first log (6.27 +/- 0.07) value for the MLH species was successfully determined, for which a crystal structure has been reported recently.

• 出版日期2013-9