The substituted benzylpiperazines, 3,4-methylenedioxybenzylpiperazine (3,4-MDBP), its regioisomer 2,3-methylenedioxybenzylpiperazine (2,3-MDBP) and four isobaric ring substituted methoxymethylbenzylpiperazines (MMBP) have almost identical mass spectra. Perfluoroacylation of the secondary amine nitrogen of these isomeric piperazines gave mass spectra with differences in relative abundance of some fragment ions. However, the spectra did not yield any unique fragments for specific identification of one isomer to the exclusion of the other compounds. Gas chromatography coupled with infrared detection (GC-IRD) provides direct confirmatory data for the structural differentiation between the six isomers. The mass spectra in combination with the vapor phase infrared spectra provide for specific confirmation of each of the isomeric piperazines. The underivatized and perfluoroacyl derivative forms of the ring substituted benzylpiperazines were resolved on the polar stationary phase Rtx-200.
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