Buffer Standards for the Physiological pH of the Zwitterionic Compound, HEPPSO from 5 to 55 °C
The values of the thermodynamic second dissociation constant, p K 2 , and related thermodynamic quantities of N-(2-hydroxyethyl)piperazine-N′-2-hydroxypropanesulfonic acid (HEPPSO) have already been reported from 5 to 55 °C, including 37 °C, by the emf method. This paper reports the results for the...
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Published in | Journal of solution chemistry Vol. 38; no. 11; pp. 1417 - 1431 |
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Main Authors | , , , , , , , , , , |
Format | Journal Article |
Language | English |
Published |
Boston
Springer US
2009
|
Subjects | |
Online Access | Get full text |
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Summary: | The values of the thermodynamic second dissociation constant, p
K
2
, and related thermodynamic quantities of N-(2-hydroxyethyl)piperazine-N′-2-hydroxypropanesulfonic acid (HEPPSO) have already been reported from 5 to 55 °C, including 37 °C, by the emf method. This paper reports the results for the pH of one chloride-free buffer solution containing the composition: (a) HEPPSO (0.08 mol⋅kg
−1
)+NaHEPPSO (0.04 mol⋅kg
−1
). The remaining seventeen buffer solutions contain a saline medium of ionic strength
I
=0.16 mol⋅kg
−1
, matching closely that of physiological fluids. Conventional pH values, denoted as p
a
H
, for all eighteen buffer solutions from 5 to 55 °C have been calculated. The operational pH values, designated as pH, with residual liquid-junction corrections for five buffer solutions, one without NaCl, and four with buffer solutions in saline media of
I
=0.16 mol⋅kg
−1
are recommended as pH standards in the range of physiological application. These are based on the NBS/NIST standard scale for pH measurements. |
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ISSN: | 0095-9782 1572-8927 |
DOI: | 10.1007/s10953-009-9442-z |