Recrystallise the hydrochloride by dissolving it in the minimum volume of super dry EtOH and adding dry Et2O or from dry Et2O. Dry it in a vacuum and store it in a vacuum desiccator with P2O5. Alternatively it could be crystallised from EtOH (containing a couple of drops of ethanolic HCl) and adding dry Et2O. Filter and dry it in a vacuum desiccator over H2SO4 and NaOH. [Pinner Chem Ber 16 1654 1883, Glickman & Cope J Am Chem Soc 67 1020 1945, Chaplin & Hunter J Chem Soc 1118 1937, McElvain & Schroeder J Am Chem Soc 71 40 1949, McElvain & Tate J Am Chem Soc 73 2233 1951, Methods Enzymol 25 585 1972, Beilstein 2 III 418.]
