SEPARATION OF DIPEPTIDES AND TRIPEPTIDES WITH SOLVENT-EXTRACTION AND AN EMULSION LIQUID MEMBRANE

The extraction equilibria of various di- and tripeptides with di-2-eth ylhexylphosphoric acid (D2EHPA) were studied at low pH values. The com plex extracted to organic phase consisted of one molecule of peptide a nd two molecules of D2EHPA dimer. The extraction constants of the pept ides correlated well with the distribution coefficients of peptides be tween 1-octanol and water, which is a measure of hydrophobicity. The p ermeation rates of peptides through an emulsion liquid membrane were e xamined by using D2EHPA as a carrier, Span 80 as an emulsifier and ker osene as a diluent. The rates varied considerably with peptide type, d epending upon the hydrophobicity.