Patent ID: 6995281

Claim:
A method of making a salt of S-[2-[(1-Iminoethyl)-amino]ethyl]-2-methyl-L-cysteine, comprising removing counterions from S-[2-[(1-Iminoethyl)-amino]ethyl]-2-methyl-L-cysteine dihydrochloride in solution by contacting S-[2-[(1-Iminoethyl)-amino]ethyl]-2-methyl-L-cysteine dihydrochloride in solution with an appropriate ion exchange membrane, separating the solution containing S-[2-[(1-Iminoethyl)-amino]ethyl]-2-methyl-L-cysteine from the ion exchange membrane, and contacting the S-[2-[(1-Iminoethyl)-amino]ethyl]-2-methyl-L-cysteine with at least one counterion other than hydrochloride ion.