Determination of the activity coefficients of glycylglycine and glycyl-L-alanine in sodium chloride solutions by an electrochemical cell with ion-selective electrodes: Experimental measurements and thermodynamic theory

M. P. Breil, J. M. Mollerup, E. S.J. Rudolph, M. Ottens, L. A.M. Van Der Wielen

Research output: Contribution to journalArticlepeer-review

Abstract

An electrochemical cell with a cation and an anion ion-selective electrode (ISE) was used to determine the activity coefficients of two dipeptides, glycylglycine (GG) and glycyl-L-alanine (GA), in aqueous NaCl solutions at 298.15K. The thermodynamic theory including possible reference states and normalisations of activity coefficients is revisited. The effect of adding dipeptide to the electrolyte solution is stronger at low salt concentration than at higher salt concentration. The change of the activity coefficient ratio of the dipeptide is most pronounced at low concentrations of both solutes. Close to saturation, GA shows salting-in.

Original languageEnglish
Pages (from-to)127-140
Number of pages14
JournalFluid Phase Equilibria
Volume191
Issue number1-2
DOIs
Publication statusPublished - 15 Nov 2001
Externally publishedYes

Keywords

  • Activity coefficient
  • Data
  • Dipeptides
  • Experimental method
  • Ion-selective electrodes
  • Salt

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