Densities of L-serine in 1,2-propanediol-water and 1,2-butanediol-water mixed solvents have been measured at 298.15 K by an oscillating-tube densimeter. Apparent molar volumes, limiting partial molar volumes, transfer volumes and hydration numbers for L-serine have been calculated. The transfer volumes from water to alcohol-water mixtures and hydration numbers have been discussed in terms of the structural hydration interaction model. The results show that the transfer volumes of serine from water to alcohol-water mixed solvents are positive and the hydration numbers decrease. These may be regarded as a result of a dominant interaction between —OH group of alcohol and ionic group of serine.

Key words: L-serine, 1,2-propanediol, 1,2-butanediol, limiting partial molar volume, structural interaction