Chromatographic and Mass Spectrometry Methods for the Differentiation of N-Methyl-1-(3,4-methylenedioxyphenyl)-2-butanamine from Regioisomeric Derivatives

Abstract

Methods are described for the gas chromatographic—mass spectrometric identification of the street drug N-methyl-1-(3,4-methylenedioxyphenyl)-2-butanamine (MBDB or MDP-2-MB) and its differentiation from two uniquely isomeric drugs, N-ethyl-3,4-methylenedioxyamphetamine (MDEA) and N,N-dimethyl-3,4-methylenedioxyamphetamine (MDMMA). These positional isomers have the same molecular weight (MW = 207) and fragment by a common mechanism under electron impact mass spectrometric conditions to yield a base peak of the same mass (m/z 72). Derivatization of the two secondary amines (MBDB and MDEA) with pentafluoropropionic anhydride (PFPA) yields amides with fragment ions which individualize their EI mass spectra. The PFPA derivative of MBDB yields diagnostic ions at m/z 160 and 176, whereas the PFPA derivative of MDEA produces ions at m/z 162 and 190. This EI spectra individualization for MBDB and MDEA is particularly significant since these two compounds have similar retention properties in the PFPA-derivatized and underivatized forms and since both are known street drugs.