Eight solvent systems are described which make it possible to separate and identify twenty-six compounds, found in narcotic seizures, by thin-layer chromatography. The separation and identification of five opium alkaloids is best achieved in the solvent systems ethyl acetate—benzene—acetonitrile—ammonium hydroxide (50:30:15:5) and acetonitrile—benzene—ethyl acetate—ammonium hydroxide (40:30:25:5). These solvent systems offer a procedure that is convenient, rapid, and highly selective for the systematic separation and identification of opiates found in narcotic seizures.