Analytical determination of purity of 1-piperidinocyclohexanecarbonitrile and its hydrobromide salt

A common contaminant of illicit phencyclidine, 1-piperidinocyclohexanecarbonitrile (I), is a very weak base compared to tertiary amines such as phencyclidine, 1-(cyclohexenyl)piperidine, and piperidine. Compound I and its hydrobromide salt can be selectively detected and quantitated in the presence of synthetic contaminants by nonaqueous titration with perchloric acid in acetonitrile. This method allows direct assay of I under conditions where decomposition is not observed.