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Equilibrium or nonequilibrium pH

Equilibrium or nonequilibrium pH <h4>The reported total concentrations of buffers A and B in the series of experiments indicate that the dilutions were not made as stated by the authors.</h4> In their paper, Nguyen et al. start with buffers A and B each at initial concentrations of 0.01 M in a volume of 20 ml to which repeated aliquots of 20 μl of 1.0148 M HCl are added. Hence, the combined concentrations of protonated and free buffers should add by simple algebra to the formula ( n is the dilution number): [ A i ] + [ HA i ] = 20 * 0.01/20 + n * 0.02 where the numerator is the conserved total amount of buffer A and the denominator is the total volume. Most of the total concentrations of buffer A given in Table 1 abide to this order, but from experiment 4 the measured total concentration was lower than expected. Apparently, an additional 20 μl were added (see R script in supplemental material, point 2). With this proviso, a correlation of 0.9999994 between stated and expected total concentration of total weak acid A is obtained. For weak acid B in experiment 2 , the authors seem to have http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png AJP - Renal Physiology The American Physiological Society

Equilibrium or nonequilibrium pH

AJP - Renal Physiology , Volume 298 (2): F472 – Feb 1, 2010

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References (4)

Publisher
The American Physiological Society
Copyright
Copyright © 2011 the American Physiological Society
ISSN
0363-6127
eISSN
1522-1466
DOI
10.1152/ajprenal.00219.2009
pmid
20103812
Publisher site
See Article on Publisher Site

Abstract

<h4>The reported total concentrations of buffers A and B in the series of experiments indicate that the dilutions were not made as stated by the authors.</h4> In their paper, Nguyen et al. start with buffers A and B each at initial concentrations of 0.01 M in a volume of 20 ml to which repeated aliquots of 20 μl of 1.0148 M HCl are added. Hence, the combined concentrations of protonated and free buffers should add by simple algebra to the formula ( n is the dilution number): [ A i ] + [ HA i ] = 20 * 0.01/20 + n * 0.02 where the numerator is the conserved total amount of buffer A and the denominator is the total volume. Most of the total concentrations of buffer A given in Table 1 abide to this order, but from experiment 4 the measured total concentration was lower than expected. Apparently, an additional 20 μl were added (see R script in supplemental material, point 2). With this proviso, a correlation of 0.9999994 between stated and expected total concentration of total weak acid A is obtained. For weak acid B in experiment 2 , the authors seem to have

Journal

AJP - Renal PhysiologyThe American Physiological Society

Published: Feb 1, 2010

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