Patent ID: 7728145

Claim:
An industrial process for recovering pure fentanyl from an impure aqueous preparation comprising fentanyl containing phenethylpiperaniline, the process comprising: subjecting said impure aqueous preparation to a reverse-phase high performance preparative liquid column chromatography, the column containing a stationary phase, the stationary phase being bonded-phase silica containing ligands selected from the group consisting of butyl-, octyl- and octadecyl-moieties, the chromatography comprising contacting the column with the aqueous preparation and then eluting the column with a mobile phase comprising an aqueous acidic solution containing an organic solvent, the aqueous mobile phase pH being in the range of from about 2.5 to about 3.5, and recovering pure fentanyl, wherein the pure fentanyl comprises a phenethylpiperaniline impurity level of less than about 0.010 weight percent, and further wherein a loading ratio of column media to fentanyl loaded onto the column is in the range of from about 50 to about 150.