Systematic Approach for Calculating the Concentrations of Chemical Species in Multiequilibrium Problems: Inclusion of the Ionic Strength Effects

Baeza-Baeza, J.J.; García-Álvarez-Coque, M.C.

doi:10.1021/ed200594u

Cited by 13 publications

(25 citation statements)

References 17 publications

(27 reference statements)

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“…Two mathematical approaches namely, the algebraic [2] , [3] and the dynamic approach [4] , [5] , [6] are available to predict the pH profiles of complex buffer systems. In this work, we explicitly derive the analytical expression for phosphate and universal buffer using algebraic as well as differential dynamic approach.…”

Section: Introductionmentioning

confidence: 99%

Dynamic approach to predict pH profiles of biologically relevant buffers

Ganesh¹,

Soumen

Ravichandran

et al. 2017

Biochemistry and Biophysics Reports

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Recently, dynamic approach has been applied to determine the steady state concentrations of multiple ionic species present in complex buffers at equilibrium. Here, we have used the dynamic approach to explicitly model the pH profiles of biologically relevant phosphate buffer and universal buffer (a mixture of three tri-protic acids such as citric acid, boric acid and phosphoric acid). The results from dynamic approach are identical to that of the conventional algebraic approach, but with an added advantage that the dynamic approach, allow for the modelling of complex buffer systems relatively easy compared to that of algebraic method.

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Section: Introductionmentioning

confidence: 99%

Dynamic approach to predict pH profiles of biologically relevant buffers

Ganesh¹,

Soumen

Ravichandran

et al. 2017

Biochemistry and Biophysics Reports

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“…Furthermore, we modeled a set of previously examined 2 clinically obtained pH values on the basis of electrolyte, albumin, phosphate, lactate, and p CO 2 values. Finally, analyses of the papers by Glaser et al 18 and Baeza-Baeza and García-Álvarez-Coque 7 are presented in brief.…”

Section: Methodsmentioning

confidence: 99%

“…Schell et al 6 augmented this dynamic approach to take ionic strength into account, again using the Davies’ equation. 8 Also, Baeza-Baeza and García-Álvarez-Coque 7 used the Davies’ equation 8 to find activity coefficients and found the equilibrium pH through minimizing a composite criterion. This consisted of the squared difference of the sum of buffer concentrations from known total values, the squared difference of charge balance from zero, and the squared final change in ionic strength after an iterative procedure.…”

Section: Introductionmentioning

confidence: 99%

Modeling Acid–Base by Minimizing Charge-Balance

Ring

Kellum

2019

ACS Omega

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In this study, we show that equilibrium pH can be obtained for any specified fluid with any number of buffers and dissociations. This is done by root finding in the equation for charge balance. We demonstrate that this equation is monotonic in proton concentration for conceivable buffers. We show that the total charge on any buffer is a function of only the total buffer concentration and pH, given the thermodynamic dissociation constants. Using the Davies’ equation as a placeholder for single-ion activity coefficients as a function of charge and ionic strength, we develop an iterative algorithm, whereby the apparent dissociation constants are updated from the thermodynamic dissociation constants, and from this, the equilibrium is also identified in the nonideal state. We show how this algebra leads to guaranteed conservation of both thermodynamic dissociation constants and total buffer concentrations because the distribution of buffer species is fixed by the updated dissociation constants, actual pH, and total buffer concentration. Strong ions are assumed to contribute fixed charges. In order to concentrate on the process of modeling the equilibrium pH alone, this algorithm is examined against a series of theoretical results in which the Davies’ equation was given the same status. However, a large sample of clinical pH measurements is also examined. To enhance the practical utility, CO 2 and albumin are present as the default condition. We developed “ABCharge”, a package in R, an open source language. The main function returns pH, activity coefficients, buffer species distribution, ionic strength, and charge balance for both the ideal and nonideal cases, for any mixture of any buffers with any number of known thermodynamic dissociation constants. Our algorithm can be updated if a more reliable and practical assessment of single-ion activities becomes available. Can Stock Photo/miceking

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“…The mathematical model to predict the

profile of simple cases such as monoprotic, diprotic, mono-alkaline and amphoteric can be easily derived using algebraic approach [6] . On the other hand, while studying the effect of salt or co-solvent on the distribution of monoprotic acid, dynamic approach is preferred because of its generality and simplicity in deriving the models [3] , [5] , [7] , [8] , [9] . In this article, we explicitly, derive the algebraic and dynamic models for amphoteric, di-amino-monoprotic, and monoprotic in the presence of salt or co-solvent [7] , [8] , [9] .…”

Section: Introductionmentioning

confidence: 99%

“…On the other hand, while studying the effect of salt or co-solvent on the distribution of monoprotic acid, dynamic approach is preferred because of its generality and simplicity in deriving the models [3] , [5] , [7] , [8] , [9] . In this article, we explicitly, derive the algebraic and dynamic models for amphoteric, di-amino-monoprotic, and monoprotic in the presence of salt or co-solvent [7] , [8] , [9] . Further, the

profiles of recently reported amphoteric molecules such as nalidixic acid, mebendazole, benazepril and telmisartan, were analysed to show the equivalence of dynamic approach and algebraic method [10] .…”

Section: Introductionmentioning

confidence: 99%

Log D analysis using dynamic approach

Krishnamoorthy¹,

Alluvada

Alemayehu

et al. 2018

Biochemistry and Biophysics Reports

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Log D the logarithm (italiclog10) of the distribution coefficient (D), is one of the important parameters used in Lipinski's rule to assess the druggability of a molecule in pharmaceutical formulations. The distribution of a molecule between a hydrophobic organic phase and an aqueous buffer phase is influenced by the pH of the buffer system. In this work, we used both the conventional algebraic method and the generalized ‘dynamic’ approach to model the distribution coefficient of amphoteric, diamino-monoprotic molecule and monoprotic acid in the presence of salt or co-solvent. We have shown the equivalence of these methods by analysing the recently reported experimental data of amphoteric molecules such as nalidixic acid, mebendazole, benazepril and telmisartan.

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Systematic Approach for Calculating the Concentrations of Chemical Species in Multiequilibrium Problems: Inclusion of the Ionic Strength Effects

Cited by 13 publications

References 17 publications

Dynamic approach to predict pH profiles of biologically relevant buffers

Dynamic approach to predict pH profiles of biologically relevant buffers

Modeling Acid–Base by Minimizing Charge-Balance

Log D analysis using dynamic approach

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