A series of ten homologous and regioisomeric aminoketones related to the designer synthetic cathinone
derivative MDPV were evaluated in this study. These compounds were prepared from a common
precursor chemical, piperonal (3,4-methylenedioxybenzaldehyde). These aminoketones show major
peaks in their mass spectra corresponding to the regioisomeric and homologous immonium cation
fragments from the loss of the methylenedioxybenzoyl radical species. All ten compounds in this study
show equivalent EI MS fragments for the 3,4-methylenedioxybenzoyl fragments (m/z 149) and the
methylenedioxybenzene fragment at m/z 121. The m/z 149 results from ionization of the carbonyl
oxygen followed by an alpha-cleavage fragmentation. The loss of CO from this ion yields the m/z 121
fragments common to all spectra. The regioisomeric aminoketones yield equivalent mass spectra
including mass equivalent regioisomeric immonium cation base peaks. A subset of these compounds has
the same molecular weight and almost identical mass spectra to that of the designer drug MDPV. An
evaluation of the effects of homologation on gas chromatographic retention showed that addition of a
methylene (CH2) in the nitrogen-containing ring increases retention more than the equivalent group
added to the alkyl side-chain.