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Differentiation of the Six Dimethoxypyrovalerone Regioisomers: GC-MS, GC-MS/MS and GC-IR

NCJ Number
Talanta Volume: 171 Dated: August 2017 Pages: 220-228
Date Published
August 2017
9 pages
Since multiple and complementary analytical methods are often necessary for the identification of a specific compound from a series of closely related structural isomers, this study used gas chromatography-mass spectrometry (GC-MS), gas chromatography-product ion mass spectrometry (GC-MS/MS), and gas chromatography-infrared spectroscopy (GC-IR) to differentiate between the six dimethoxypyrrovalerone (DMPV) regioisomers.

The six regioisomeric aminoketones were separated on a 50-percent phenyl stationary phase and the elution order is related to the positioning of substituents on the aromatic ring. These six DMPV regioisomers yield essentially identical mass spectral data in both chemical ionization (CI-MS) and electron ionization (EI-MS) spectra, as well as identical product ion MS/MS spectra of the iminium castion peak (m/z 126). These various mass spectral techniques provide data to identify all major structural features of these molecules except the dimethoxy substitution pattern of the aromatic ring. The region of the vapor phase infrared spectra between 1600 cm-1 and 1000 cm-1 provides a significant number of unique absorption bands characteristic of each individual DMPV regioisomer. (Publisher abstract modified)

Date Published: August 1, 2017