Abstract
The second acidic dissociation constants pK 2 of the ampholyte N-(2-hydroxyethyl) piperazine-N′-2-hydroxypropanesulfonic acid (HEPPSO) have been determined at seven temperatures from 5 to 55°C from emf measurements utilizing hydrogen and silver–silver chloride cells without liquid junction. The thermodynamic quantities, ΔG°, ΔH°,ΔS°, and Δ C op have been calculated from the temperature coefficient of pK 2. At 25°C, the pK 2 = 8.042 and at 37°C, pK 2 = 7.876; hence, buffer solutions of HEPPSO and NaHEPPSOate are important for pH control in the region close to that of clinical fluids (blood serum). Conventional pH values from 5 to 55°C as well as those obtained from liquid junction correction at 25 and 37°C have been reported for three buffer solutions with the compositions (molality scale): (1) equimolal mixture of HEPPSO (0.04 m) + NaHEPPSOate (0.04 m) + NaCl (0.12 m); (2) HEPPSO (0.08 m) + NaHEPPSOate (0.08 m); and (3) HEPPSO (0.08 m) + NaHEPPSOate (0.08 m) + NaCl (0.08 m).
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REFERENCES
N. E. Good, G. D. Winget, W. Winter, T. N. Connolly, S. Izawa, and R. N. Snigh, Biochemistry 5, 467 (1966).
W. J. Ferguson, K. H. Braunschweiger, W. R. Braunschweiger, C. C. Wasman, N. P. Jarvis, D. H. Bell, and N. E. Good, Anal Biochem. 104(2), 300 (1980).
Research Organics Inc., 1996–1997 catalog, p. 216, and references listed therein.
R. N. Roy, J. J. Gibbons, C. W. Krueger, and G. Lacross, Jr., J. Chem. Thermodyn. 9, 2355 (1977).
R. N. Roy, R. A. Robinson, and R. G. Bates, J. Am. Chem. Soc. 95, 8231 (1973).
R. N. Roy, D. R. Mrad, P. A. Lord, J. A. Carlsten, W. S. Good, P. Allsup, L. N. Roy, K. M. Kuhler, Y. C. Wu, and W. F. Koch; Anal. Chem., submitted.
R. G. Bates, R. N. Roy, and R. A. Robinson, Anal. Chem. 45, 1663 (1973).
R. N. Roy, C. P. Moore, D. M. Bliss, S. Patel, A. Kilker, J. A. Carlsten, W. S. Good, and L. N. Roy, J. Chem. Thermodyn. 42, 1 (1997).
C. A. Vega, and R. G. Bates, Anal. Chem. 48, 1293 (1976).
D. Feng, W. F. Koch, and Y. C. Wu, Anal. Chem. 61, 1400 (1989).
R. N. Roy, E. E. Swenson, G. LaCross, Jr., and C. W. Krueger, Anal. Chem. 47, 1407 (1975).
R. Gary, R. G. Bates, and R. A. Robinson, J. Phys. Chem. 68, 1186 (1964).
R. G. Bates, Determination of pH, 2nd. edn. (Wiley, New York, 1973), Chaps.4, 10.
Y. C. Wu, D. Feng, and W. F. Koch, J. Solution Chem. 18, 641 (1989).
W. M. Latimer, Oxidation Potentials, 2nd. edn. (Prentice Hall, New York, 1952).
H. S. Harned and R. W. Ehlers, J. Am. Chem. Soc. 54, 1350 (1932).
R. N. Roy, J. Bice, J. Greer, J. A. Carlsten, J. Smithson, W. S. Good, C. P. Moore, L. N. Roy, and K. M. Kuhler, J. Chem. Eng. Data 42, 41 (1997).
D. J. G. Ives and P. G. N. Moseley, J. Chem. Soc. Farad. Trans. I, 72, 1132 (1976).
N. W. Please, Biochemistry 56, 196 (1954).
R. G. Bates, J. Res. Nat. Bur. Standards A 66, 179 (1962).
K. S. Pitzer, and G. Mayonga, J. Phys. Chem. 77, 2300 (1973).
K. S. Pitzer and K. K. Kim, J. Am. Chem. Soc. 96, 5701 (1974).
C. Chan, Y. Eng, and K. Eu, J. Chem. Eng. Data 40, 685 (1995).
A. K. Covington and M. I. A. Ferra, J. Solution Chem. 23, 1 (1994).
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Roy, R.N., Cramer, J., Randon, V. et al. Buffers for the Physiological pH Range: Thermodynamics of the Second Dissociation of N-(2-Hydroxyethyl)piperazine-N′-2-hydroxypropanesulfonic Acid From 5 to 55°C. Journal of Solution Chemistry 27, 425–434 (1998). https://doi.org/10.1023/A:1022600604950
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DOI: https://doi.org/10.1023/A:1022600604950