Patent ID: 7566401

Claim:
A normal phase high performance liquid chromatographic process for separating, eluting, and isolating xanthine(s) and polar protic monomer(s) from polar protic oligomer(s) comprises the steps of: (a) introducing a liquid sample containing the xanthine(s), the polar protic monomer(s), and the polar protic oligomer(s) into a liquid chromatography column packed with a polar bonded stationary phase selected from the group consisting of a diol phase, a glycerol phase, an amino phase, a cyano phase, a trimethylsilyl phase, a dimethylsilyl phase, a halogenated phase, and a nitro phase; (b) passing an isocratic mobile phase consisting essentially of a polar aprotic solvent through the column to elute the xanthine(s) and the polar protic monomer(s); (c) isolating one or more individual fractions containing the xanthine(s) and the polar protic monomer(s); and (d) optionally recovering the isolated xanthine(s) and/or the isolated polar protic monomer(s).