Determination of Partition Coefficients of Labile Compounds Subject to Dissociation Extraction Analysis of Partitioning

A novel method for the determination of partition coefficients in aqueous-organic two-phase systems is described. It is applicable for characterizing the distribution of substances undergoing proton dissociation in the aqueous phase. The method is based on titration by means of the organic phase. A linear form of the respective model is given for parameter estimation by linear regression. This strategy is used for the determination of the partition coefficients of some N-unprotected n-alkyl esters of phenylalanine in various aqueous-organic biphasic systems. These esters are of interest for the optical resolution of phenylalanine with chymotrypsin.