GC-MS and GC-IR Analyses of the Methoxy-1-n-pentyl-3-(1-naphthoyl)-indoles: Regioisomeric Designer Cannabinoids

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Thaxton-Weissenfluh A, Belal TS, DeRuiter J, Smith F, Abiedalla Y, Neel L, Abdel-Hay KM, Clark CR.

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J Chromatogr Sci. 2018 Oct 1;56(9):779-788. doi: 10.1093/chromsci/bmy059.

Abstract

The indole ring regioisomeric methoxy-1-n-pentyl-3-(1-naphthoyl)-indoles represent indole ring-substituted analogs of the synthetic cannabinoid JWH-018. The electron ionization mass spectra show equivalent regioisomeric major fragments resulting from cleavage of the groups attached to the central indole nucleus. The characteristic (M-17)+ fragment ion at m/z 354 resulting from the loss of OH group is significant in the mass spectra of all four compounds. Fragmentation of the naphthoyl and/or pentyl groups yields the cations at m/z 314, 300, 244 and 216. The vapor-phase infrared spectra provide a number of characteristic absorption bands to identify the individual isomers. Gas chromatographic separations on a capillary column containing a film of trifluoropropylmethyl polysiloxane (Rtx-200) provided excellent resolution of these compounds, their precursor indoles and intermediate pentylindoles. The elution order appears related to the degree of crowding of indole ring substituents.

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Link/DOI: 10.1093/chromsci/bmy059