The partitioning behavior of L-methionine has been studied in aqueous two-phase systems of poly (propylene glycol) + sodium phosphate salts + H2O at different temperatures. The effects of tie line length, salt type, and temperature on the partition coefficient of this amino acid have been studied. In addition, thermodynamic parameters ( H!, S!and G!) as a function of temperature were calculated. The results showed that increasing tie line length led to decreasing of the partition coefficient. We also showed that the partition coefficients of the amino acid in the systems containing Na3PO4 are greater than the other two salts. Moreover, it is verified that increasing temperature led to decreasing the partition coefficient.
