Resolution and analysis of enantiomers of amphetamines by liquid chromatography on a chiral stationary phase: collaborative study

A rapid, accurate method for separating and determining the enantiomeric composition of amphetamine bulk drug and commercial preparations was developed and subjected to collaborative study. Amide derivatives of the amphetamine enantiomers are formed by using achiral 2-naphthoyl chloride. The resulting enantiomeric amides are then chromatographed on a commercially available chiral stationary phase with hexane-isopropyl alcohol-acetonitrile (97 + 3 + 0.5) mobile phase, with detection at 254 nm. Seven collaborators received bulk drug and commercial samples of amphetamine. The collaborators and authors determined the mean percent l- and d-amphetamine from 2 injections of each sample. The method can detect the presence of as little as 0.5% of the l-enantiomer in d-amphetamine, with reproducibility between laboratories of +/- 71.3%. The method has been adopted official first action for determination of the enantiomeric composition of amphetamine bulk drug and preparations.