Enantiomeric resolution of methylamphetamine and ephedrine: Does this affect the δ13C, δ15N, and δ2H stable isotope ratios of the product?

The use of stable isotope ratio mass spectrometry (IRMS) as a profiling tool for methylamphetamine has evolved over the last decade. Stable isotope ratios of carbon (δ13C), nitrogen (δ15N), and hydrogen (δ2H) of methylamphetamine are useful in determining the precursor used to manufacture methylamphetamine, and in many cases the synthetic origin of the methylamphetamine precursor. More recently, samples of seized methylamphetamine show that a resolution step is being employed in the manufacturing process. We sought to determine whether the δ13C, δ15N, and δ2H values were affected by either a resolution performed on racemic methylamphetamine or a resolution on racemic ephedrine, a commonly used precursor to methylamphetamine. We found that for the types of resolution studied, IRMS is still able to provide useful information on the provenance of a methylamphetamine sample.