METHODS FOR THE DIFFERENTIATION OF METHAMPHETAMINE FROM REGIOISOMERIC PHENETHYLAMINES

The analytical profiles are described for five amines, methamphetamine, and four isomeric phenethylamines of MW = 149. These five amines all contain an unsubstituted benzyl moiety, thus the regioisomerism is within the carbon-carbon bond located alpha- to the amine moiety. Therefore these phenethylamines are regioisomeric within the imine fragment (m/z = 58), which is the base peak in the electron impact (EI) mass spectrum of methamphetamine. The ultraviolet absorption spectra for these compounds show the characteristic phenethylamine absorption bands in the (250 - 260 nm) range. These amines are best differentiated by chromatographic separation and are well resolved by liquid chromatographic techniques. The five regioisomeric amines are separated using an isocratic reversed-phase system consisting of a C18 stationary phase and a mobile phase of pH 3 phosphate buffer and methanol. The elution order under these conditions appears to parallel the length of the carbon chain attached to the aromatic ring.