Premium
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
Author(s) -
Billing Caren,
Cukrowski Ignacy,
Jordan Blake
Publication year - 2013
Publication title -
electroanalysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.574
H-Index - 128
eISSN - 1521-4109
pISSN - 1040-0397
DOI - 10.1002/elan.201300256
Subject(s) - polarography , picolinic acid , chemistry , metal , diffusion , ionic strength , ionic bonding , metal ions in aqueous solution , ligand (biochemistry) , pyridine , carboxylic acid , inorganic chemistry , ion , analytical chemistry (journal) , chromatography , medicinal chemistry , organic chemistry , thermodynamics , biochemistry , physics , receptor , aqueous solution
A new polarographic procedure has been developed for the study of metal‐ligand equilibria at pH<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; DC TAST polarography was employed at 25 °C and ionic strength of 0.25–0.5 M (H,Na)NO 3 . Log β values of 4.26±0.03, 7.86±0.11 and 10.47±0.12 were obtained for the ML, ML 2 and ML 3 complexes, respectively, and compare well to literature values. The first log β (6.27±0.07) value for the MLH species was successfully determined, for which a crystal structure has been reported recently.