Studies on Partial Molar Volumes of Some Amino Acids and Their Groups in Aqueous Solutions from 293.15K to 333.15K

摘要

Abstract Densities of aqueous solutions of eight amino acids, glycine, L-alanine, L-valine, L-isoleucine, L-serine, L-threonine, L-arginine and L-phenylalanine, are measured as a function of amino acid concentration from 293.15 K to 333.15 K. These data are used to calculate the apparent molar volume Vφ^0 and infinite dilution apparent molar volume Vφ^0 (partial molar volume). Data of five amino acids are used to correlate partial molar volume Vφ^0 using group contribution method to estimate the contributions of the zwitterionic end groups (NH+,COO-) and CH2 group, OH group, CNHNHNH2 group and C6H5(phenyl) group of amino acids. The results show that Vφ^0 values for all kinds of groups of amino acids studied increase with increase of temperature except those for CH2^φ group, which are almost constant within the studied temperature range. Data of other amino acids, L-valine, L-isoleucine and L-threonine, are chosen for comparison with the predicted partial molar volume Vφ^0 using the group additivity parameters obtained. The results confirm that this group additivity method has excellent predictive utility.