Chemical speciation of amino acids in electrolyte solutions containing major components of natural fluids

Abstract

Protonation constants of glycine, DL α-alanine, L(-)histidine, L(+)lysine, L(-)serine, iminodiacetic, L(+)aspartic, and L(+)glutamic acids, in aqueous NaCl, MgCl2, CaCl2, (C2H5)4NI and Na2SO4 solutions have been determined in different temperature-ionic strength conditions (1 atm pressure), using the pH-metric technique. The differences in protonation constants determined in different salt solutions were explained using a complex formation model. Particular attention has been paid to obtaining thermodynamic formation data for natural conditions, such as that of seawater. A general model for the weak interactions between amino acids and alkali and alkaline earth chlorides and sulfates is discussed. © 1995 Taylor and Francis Group, LLC.