The pH of any mixture of monoprotic acids and bases

Herman, Dave; Booth, K. K.; Parker, O. J.; Breneman, G. L.

doi:10.1021/ed067p501

Cited by 10 publications

(4 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…I show here that Stewart and an equivalent formula published in 1990 by Herman et al (2) can predict the measured pH equally well, but much easier from these initial values. However, clarification is needed on exactly how these preequilibrium values were obtained.…”

supporting

confidence: 54%

Equilibrium or nonequilibrium pH

Ring

2010

American Journal of Physiology-Renal Physiology

View full text Add to dashboard Cite

supporting

confidence: 54%

Equilibrium or nonequilibrium pH

Ring

2010

American Journal of Physiology-Renal Physiology

View full text Add to dashboard Cite

“…The derivation of the theoretical model is presented in complete form as supplementary material ( S1 Text ), but here, in an overview to facilitate understanding is first shown results to demonstrate in the simplest possible system the meaning of the statement that protons are not additive. Then the effect of a single monovalent weak acid as derived in [ 3 – 5 , 12 , 13 ] is presented.…”

Section: Methodsmentioning

confidence: 99%

“…Already in 1914, Spiro and Koppel [ 3 ] noticed that in contrast to electrolytes and total concentrations of weak acids and bases, protons and hydroxyl ions are not additive in fluids with a pH observed in plasma or urine, and wrote equations, based on the principle of charge balance, from which to deduce the [H + ]. Although these insights were confirmed [ 4 , 5 ]the traditional discourse in acid-base has taken another path. Hence, noting that hydrogen is ubiquitously produced in metabolism [ 6 ] quantitative accounting of acid-base chemistry has been attempted indirectly in terms of summation of metabolites known to be involved in producing or neutralizing protons [ 7 ].…”

Section: Introductionmentioning

confidence: 99%

Strong Relationships in Acid-Base Chemistry – Modeling Protons Based on Predictable Concentrations of Strong Ions, Total Weak Acid Concentrations, and pCO2

Ring¹,

Kellum

2016

PLoS ONE

View full text Add to dashboard Cite

Understanding acid-base regulation is often reduced to pigeonholing clinical states into categories of disorders based on arterial blood sampling. An earlier ambition to quantitatively explain disorders by measuring production and elimination of acid has not become standard clinical practice. Seeking back to classical physical chemistry we propose that in any compartment, the requirement of electroneutrality leads to a strong relationship between charged moieties. This relationship is derived in the form of a general equation stating charge balance, making it possible to calculate [H+] and pH based on all other charged moieties. Therefore, to validate this construct we investigated a large number of blood samples from intensive care patients, where both data and pathology is plentiful, by comparing the measured pH to the modeled pH. We were able to predict both the mean pattern and the individual fluctuation in pH based on all other measured charges with a correlation of approximately 90% in individual patient series. However, there was a shift in pH so that fitted pH in general is overestimated (95% confidence interval -0.072–0.210) and we examine some explanations for this shift. Having confirmed the relationship between charged species we then examine some of the classical and recent literature concerning the importance of charge balance. We conclude that focusing on the charges which are predictable such as strong ions and total concentrations of weak acids leads to new insights with important implications for medicine and physiology. Importantly this construct should pave the way for quantitative acid-base models looking into the underlying mechanisms of disorders rather than just classifying them.

show abstract

“…Understanding of acid–base physiology can be obtained through deriving rules that allow prediction of pH from elementary measurements. , The possibility of achieving this is equivalent with the ability to calculate pH from the chemical constituents of a given fluid. The underpinnings for these calculations are the thermodynamic principles for dissociation and mass conservation and the requirement for balance between moieties with positive and negative charges.…”

Section: Introductionmentioning

confidence: 99%

Modeling Acid–Base by Minimizing Charge-Balance

Ring

Kellum

2019

ACS Omega

View full text Add to dashboard Cite

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

show abstract

The pH of any mixture of monoprotic acids and bases

Abstract: 115. Bits and pieces, 44. The pH of any mixture of monoprotic weak and strong acids and bases can be calculated. A curve can also be plotted for the titration of the mixture by any monoportic weak or strong acid or base.

Cited by 10 publications

References 0 publications

Equilibrium or nonequilibrium pH

Equilibrium or nonequilibrium pH

Strong Relationships in Acid-Base Chemistry – Modeling Protons Based on Predictable Concentrations of Strong Ions, Total Weak Acid Concentrations, and pCO2

Modeling Acid–Base by Minimizing Charge-Balance

Contact Info

Product

Resources

About