Extraction of tryptophan with a solution of dinonylnaphthalenesulfonic acid in heptane

The extraction of tryptophan from aqueous-salt solutions with a liquid sulfocationite (a solution of dinonylnaphthalenesulfonic acid in heptane) was studied over wide ranges amino acid concentrations and pH values. The amounts of tryptophan extracted in the cationic and zwitterionic forms were calculated.