NMR determination of the enantiomer composition of penicillamine using an optically active europium shift reagent

An NMR method is described for assaying the enantiomer composition of the pharmacologically active material penicillamine ( 1 ), using tris-(3-heptafluorobutyryl-d-camphorato)europium. The L enantiomer can be detected at levels of 0·4 to 0·5% in DL mixtures. Problems due to the insolubility of penicillamine in nonpolar solvents can be overcome by a two step derivatisation procedure.