Since three regioisomeric 3, 4-methylenedioxyphenethylamines having the same molecular weight and major mass spectral fragments of equal mass have been reported as drugs of abuse in recent years, the three methylenedioxyphenethylamines were resolved from the ethoxyphenethylamines by capillary gas chromatography using an Rxi-50 stationary phase.
These three compounds are 3,4-methylenedioxy-N-ethylamphetamine (MDEA), 3,4-methylenedioxy-N,N-dimethylamphetamine (MDMMA), and N-methyl-1-(3,4-methylenedioxyphenyl)-2-butanamine (MBDB). Ring substituted ethoxy phenethylamines having the same side chain are compounds with an isobaric relationship to these controlled drug substances, and all have molecular weight of 207 and major fragment ions in their electron ionization mass spectra at m/z 72 and 135/136. The trifluoroacetyl, pentafluoropropionyl and heptafluorobutryl derivatives of the secondary amines were evaluated in GC-MS studies. The mass spectra for these derivatives were significantly individualized and the resulting unique fragment ions allowed for specific side chain identification. The perfluoroacyl derivatives showed reasonable resolution on a non-polar stationary phase such as Rtx-1. GC-IRD studies provided structure-IR spectra relationships used for the discrimination of the three target drugs (MDEA, MDMMA and MBDB) from the other nine ring substituted ethoxyphenethylamine regioisomers. (publisher abstract modified)