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 |
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| Authors: | Caren Billing Ignacy Cukrowski Blake Jordan |
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| Affiliation: | 1. Molecular Sciences Institute, School of Chemistry, University of the Witwatersrand, P.?O. Wits, Johannesburg, 2050, South Africa;2. Department of Chemistry, University of Pretoria, Pretoria, 0002, South Africa |
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| Abstract: | 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; DCTAST polarography was employed at 25 °C and ionic strength of 0.25–0.5 M (H,Na)NO3. Log β 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 β (6.27±0.07) value for the MLH species was successfully determined, for which a crystal structure has been reported recently. |
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| Keywords: | Cadmium Diffusion junction potential Formation constants Picolinic acid Voltammetry |
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