Determination of Dextro- and Levomethorphan Mixtures Using Chiral Lanthanide NMR Shift Reagents

Europium and praseodymium chiral NMR shift reagents were used to differentiate between dextro- and levomethorphan. The enantiomeric shift differences (ΔΔδ) demonstrated by the singlet associated with the methoxy protons were large enough to identify the levo- and dextro-isomers and to allow for the determination of as little as 10% of one enantiomer in the presence of the other in a prepared mixture. The analytical method is rapid and can analyze samples as small as 1mg.