Comments on “Calculation of activity and solubility of amino acids in aqueous solution by cubic-plus-association equation of state by Sajadian and Peyvandi [Fluid Phase Equilib. 425 (2016) 152-157]”

The modeling investigation of Sajadian and Peyvandi [Fluid Phase Equilib 425 (2016) 152-157] has been carefully studied. The applied combining rule for association strength of water-amino acid is not clear. All substances were considered associating so that the results of the model depend on the applied combining rule of CPA EOS.