scholarly journals Stabilization of the Computation of Stability Constants and Species Distributions from Titration Curves

Computation ◽  
2021 ◽  
Vol 9 (5) ◽  
pp. 55
Author(s):  
Stephan Daniel Schwoebel ◽  
Dominik Höhlich ◽  
Thomas Mehner ◽  
Thomas Lampke
Keyword(s):  
Stability Constants ◽  
Thermodynamic Equilibrium ◽  
Measurement Errors ◽  
Alternative Model ◽  
Chemical Engineering ◽  
Species Distributions ◽  
Titration Curves ◽  
Deposited Metal ◽  
The Stability ◽  
Nickel Electrolyte

Thermodynamic equilibria and concentrations in thermodynamic equilibria are of major importance in chemistry, chemical engineering, physical chemistry, medicine etc. due to a vast spectrum of applications. E.g., concentrations in thermodynamic equilibria play a central role for the estimation of drug delivery, the estimation of produced mass of products of chemical reactions, the estimation of deposited metal during electro plating and many more. Species concentrations in thermodynamic equilibrium are determined by the system of reactions and to the reactions’ associated stability constants. In many applications the stability constants and the system of reactions need to be determined. The usual way to determine the stability constants is to evaluate titration curves. In this context, many numerical methods exist. One major task in this context is that the corresponding inverse problems tend to be unstable, i.e., the output is strongly affected by measurement errors, and can output negative stability constants or negative species concentrations. In this work an alternative model for the species distributions in thermodynamic equilibrium, based on the models used for HySS or Hyperquad, and titration curves is presented, which includes the positivity of species concentrations and stability constants intrinsically. Additionally, in this paper a stabilized numerical methodology is presented to treat the corresponding model guaranteeing the convergence of the algorithm. The numerical scheme is validated with clinical numerical examples and the model is validated with a Citric acid–Nickel electrolyte. This paper finds a stable, convergent and efficient methodology to compute stability constants from potentiometric titration curves.

scholarly journals Ternary Complexes in Solution, XX

1974 ◽  
Vol 29 (9-10) ◽  
pp. 654-657 ◽  
Author(s):  
Beda E. Fischer ◽  
Helmut Sigel
Keyword(s):  
Potentiometric Titration ◽  
Stability Constants ◽  
Ternary Complexes ◽  
Enhancing Effect ◽  
Titration Curves ◽  
The Stability ◽  
Comparison Of The Results

The stability constants of the ternary Cu2+ complexes containing 1,2-diaminobenzene and oxalate or salicylate have been calculated from potentiometric titration curves published by G. K. CHATURVEDI and J. P. TANDON (Z. Naturforsch. 23b, 303 [1968]; 25b, 26 [1970]). A comparison of the results with data of the literature reveals that the qualities of 1,2-diaminobenzene in ternary complexes correspond to those of ethylenediamine, while the qualities of both amines differ considerably from those of 2,2′-bipyridyl, which has a stability-enhancing effect.

Stability constants of phosphineacetate complexes of divalent metals

1979 ◽  
Vol 44 (8) ◽  
pp. 2460-2464 ◽  
Author(s):  
Jana Podlahová
Keyword(s):  
Aqueous Solutions ◽  
General Formula ◽  
Stability Constants ◽  
Statistical Processing ◽  
The Other ◽  
Divalent Metals ◽  
Titration Curves ◽  
The Stability

Anions of the phosphineacetic acids of the general formula (C6H5)3-nP(CH2COOH)n (n = 1-3) form with the cations Mn2+, Co2+, Zn2+, Cd2+, and Pb2+ in aqueous solutions complexes with the ratio M : L = 1 : 1 and in some cases also 1 : 2. In addition, the ligand with n = 3 exhibits the formation of the protonized complexes MHL. The stability constants of the complexes were calculated by statistical processing of the pH-metric titration curves, and the ligands were found to act as the O-donors to Mn2+ and Zn2+, and as PO (n = 1) and POO (n = 2, 3) donors to the other cations.

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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