The activity coefficients of glycine, DL-serine and DL-valine in aqueous solutions containing nitrates at 298.15 K

An electrochemical method was used to measure the mean activity coefficient s of amino acids in water-electrolyte-amino acid systems. The amino acids w ere glycine, DL-serine and DL-valine and the electrolytes were KNO3 and NaN O3. The activity coefficients of the electrolytes were obtained from the e. m.f measurements in an electrochemical cell with an anion and a cation ion- selective electrodes, each measured versus a double junction reference elec trode at 298.15 K. The activity coefficients of the amino acids in the tern ary systems were obtained from those of the electrolyte according to the cr oss differential relation. A simple semi-empirical model based on a modific ation of a more complex form, derived from perturbation theory, was used to correlate the activity coefficients in binary aqueous solutions and in ter nary systems.