The silver–pyrazole electrode and its application to determine the stability of Cd(II), Zn(II), Ni(II), Co(II) pyrazole complexes

1977 ◽  
Vol 55 (2) ◽  
pp. 199-202 ◽  
Author(s):  
Marie-José Blais ◽  
Guy Berthon
Keyword(s):  
Metal Complex ◽  
Metal Concentration ◽  
Stability Constants ◽  
Divalent Metal ◽  
The Stability ◽  
Concentration Ratios

The silver–pyrazole metal-complex electrode was investigated and used to determine free concentrations of pyrazole in the presence of Cd2+, Zn2+, Ni2+, or Co2+ ion, under different pyrazole/divalent metal concentration ratios. The stability constants of the complexes formed between these ions and pyrazole were calculated.

Fletcher–Powell minimization of analytical potentiometric data by microcomputer: application to the Cu(II) complexes of biological polyamines

1985 ◽  
Vol 63 (11) ◽  
pp. 3122-3128 ◽  
Author(s):  
Douglas M. Templeton ◽  
Bibudhendra Sarkar
Keyword(s):  
Biological Activity ◽  
Metal Complex ◽  
Stability Constants ◽  
Speciation Analysis ◽  
Complex Stability ◽  
Minimization Algorithm ◽  
The Stability ◽  
Best Fit ◽  
Complex Stability Constants ◽  
Potentiometric Data

The Fletcher–Powell minimization algorithm has been successfully implemented for the extraction of metal complex stability constants from analytical potentiometric data. The procedure has been adapted to run on a microcomputer with acceptable execution times, and several strategies are employed to speed convergence and avoid false minima. This allows economical minimization for a large number of models of speciation, and improves the reliability of the proposed best fit by encouraging the checking of more models than previously possible. The Ni(II)–glycine system has been analyzed and excellent agreement with the stability constants of an earlier multi-laboratory study has been attained. The system proves useful in the evaluation of both analytical and computational methods. The procedure has also been used for speciation analysis of the Cu(II) complexes of the growth regulating polyamines, spermine, and spermidine. Both systems form fully deprotonated complexes at physiological pH, which are relevant to their biological activity.

Studies on the solvent extraction of metal dithiocarbamates

1969 ◽  
Vol 47 (12) ◽  
pp. 2320-2323 ◽  
Author(s):  
Vedula S. Sastri ◽  
Keijo I. Aspila ◽  
Chuni L. Chakrabarti
Keyword(s):  
Solvent Extraction ◽  
Stability Constants ◽  
Divalent Metal ◽  
Divalent Metal Ions ◽  
Extraction Constants ◽  
Overall Stability ◽  
Stability Constants Of Complexes ◽  
Dithiocarbamic Acid ◽  
The Stability ◽  
Metal Dithiocarbamates

Studies on the solvent extraction of morpholine dithiocarbamic acid complexes of divalent metal ions Mn, Fe, Co, Ni, Cu, Zn, Pb, Cd, Hg, and Sn were carried out, and the extraction constants and the overall stability constants were determined. The stability constants of complexes of Cu(II) formed with various substituted dithiocarbamic acids, showed a variation of the stability constants with the basicity of the nitrogen and sulfur atoms in the reagents.

Stability constants and spectral studies of complexes of 2-hydroxy-5-methylazobenzene-2′-carboxylic acid with some divalent metal ions

1984 ◽  
Vol 62 (11) ◽  
pp. 2299-2301
Author(s):  
C. Mahalingam ◽  
J. K. Sthapak ◽  
D. D. Sharma ◽  
R. L. Tiwari ◽  
Smita Sthapak
Keyword(s):  
Carboxylic Acid ◽  
Metal Ions ◽  
Metal Complexes ◽  
Stability Constants ◽  
Divalent Metal ◽  
Reflectance Spectra ◽  
Spectral Studies ◽  
Divalent Metal Ions ◽  
The Stability

The stability constants of metal complexes of 2-hydroxy-5-methylazobenzene-2′-carboxylic acid have been determined spectrophotometrically. These follow the Irving–Williams sequence: log KOH(H) = 10.67, log K1(Co) = 9.02, log K1(Ni) = 9.68, log K1(Cu) = 13.37, log K1(Zn) = 7.58, and [Formula: see text]The chelates of Mn(II), Fe(II), Co(II), Ni(II), Cu(II), Zn(II), and [Formula: see text] with the dye have been prepared and characterized on the basis of their ir and reflectance spectra.

Extraction of strontium and barium salts by the nitrobenzene solution of dicarbolide in the presence of glymes

1985 ◽  
Vol 50 (3) ◽  
pp. 581-599 ◽  
Author(s):  
Petr Vaňura ◽  
Emanuel Makrlík
Keyword(s):  
Stability Constants ◽  
Organic Phase ◽  
Equilibrium Constants ◽  
Minor Role ◽  
Nitrobenzene Solution ◽  
Ligand Structure ◽  
Stability Constants Of Complexes ◽  
Separation Factors ◽  
The Stability ◽  
A Minor

Extraction of microamounts of Sr2+ and Ba2+ (henceforth M2+) from the aqueous solutions of perchloric acid (0.0125-1.02 mol/l) by means of the nitrobenzene solutions of dicarbolide (0.004-0.05 mol/l of H+{Co(C2B9H11)2}-) was studied in the presence of monoglyme (only Ba2+), diglyme, triglyme, and tetraglyme (CH3O-(CH2-CH2O)nCH3, where n = 1, 2, 3, 4). The distribution of glyme betweeen the aqueous and organic phases, the extraction of the protonized glyme molecule HL+ together with the extraction of M2+ ion and of the glyme complex with the M2+ ion, i.e., ML2+ (where L is the molecule of glyme), were found to be the dominating reactions in the systems under study. In the systems with tri- and tetraglymes the extraction of H+ and M2+ ions solvated with two glyme molecules, i.e., the formation of HL2+ and ML22+ species, can probably play a minor role. The values of the respective equilibrium constants, of the stability constants of complexes formed in the organic phase, and the theoretical separation factors αBa/Sr were determined. The effect of the ligand structure on the values of extraction and stability constants in the organic phase is discussed.

Studies on the Coordination Reaction of VO2+ and Tannic Acid in the Tannin Extract Desulfurization

2012 ◽  
Vol 239-240 ◽  
pp. 1573-1576
Author(s):  
Zhu Qing Gao ◽  
Xiao Dong Cai ◽  
Kai Cheng Ling
Keyword(s):  
Stability Constants ◽  
Tannic Acid ◽  
Ph Value ◽  
Protonation Constants ◽  
Conditional Stability ◽  
Tannin Extract ◽  
Acid Effect ◽  
Different Temperatures ◽  
The Stability ◽  
Apparent Stability

At different temperatures, the protonation constants of tannic acid and the complex apparent stability constants between tannic acid and VO2+ were determined by using pH potentimetric method. The results showed that the protonation constants and the complex apparent stability constants slightly decreased with the raising temperature. In accordance with the pH value in the tannin extract technology, the conditional stability constants of the complex were calculated on the basis of the acid effect of tannic acid and the hydrolysis effect of VO2+. It was found that pH greatly affected the stability constants of the complex , so pH must be strictly controlled in the tannin extract technology.

Complexation of Iron with the Orally Active Decorporation Drug L1 (3-Hydroxy-1,2-Dimethyl-4-Pyridinone)

1992 ◽  
Vol 38 (4) ◽  
pp. 562-565 ◽  
Author(s):  
M A Kline ◽  
C Orvig
Keyword(s):  
Blood Plasma ◽  
Potentiometric Titration ◽  
Stability Constants ◽  
Computer Model ◽  
Chelating Agent ◽  
Glass Electrode ◽  
Simple Computer ◽  
Active Iron ◽  
The Stability ◽  
Orally Active

Abstract The stability constants for the Fe(III) complexes of the orally active iron decorporation drug L1 (3-hydroxy-1,2-dimethyl-4-pyridinone) have been determined by potentiometric titration [glass electrode, 25.0 degrees C, mu = 0.15 mol/L (isotonic) NaCl]. A simple computer model of blood plasma (citrate 100 mumol/L, transferrin 37 mumol/L) has been used to compare the Fe(III) binding efficacies in blood of L1 and the clinically used intravenously administered chelating agent deferoxamine.

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