Nano liquid chromatography-high-resolution mass spectrometry for the identification of metabolites of the two new psychoactive substances N-(ortho-methoxybenzyl)-3,4-dimethoxyamphetamine and N-(ortho-methoxybenzyl)-4-methylmethamphetamine.

Two new hallucinogens, 3,4-DMA-NBOMe and 4-MMA-NBOMe, are extensively metabolized in rats and human liver preparations. Using nano liquid chromatography with high-resolution mass spectrometry, 38 metabolites of 3,4-DMA-NBOMe and 33 metabolites of 4-MMA-NBOMe were identified. The main metabolic pathways are O-demethylation and glucuronic acid conjugation for 3,4-DMA-NBOMe, and oxidation of the tolyl group to carboxylic acid for 4-MMA-NBOMe. The nanoLC approach performed comparably to conventional UHPLC. Standard urine screening methods could detect an estimated low user dose only through metabolites. Suggested screening targets include O-demethyl- and O,O-bis-demethyl-3,4-DMA-NBOMe and their glucuronides, and carboxy-4-MMA-NBOMe and its glucuronide and N-demethyl-carboxy-4-MMA-NBOMe.

Study at a glance

Abstract

Among the emerging new psychoactive substances (NPS), compounds carrying an N-ortho-methoxybenzyl substituent, the so-called NBOMes, represented a highly potent group of new hallucinogens. Recently, 3,4-dimethoxyamphetamine (3,4-DMA)-NBOMe and 4-methylmethamphetamine (4-MMA)-NBOMe occurred, but no data on their pharmacokinetics were available. According to other NBOMes, they are expected to be extensively metabolized. For detection and identification of their phase I and II metabolites, nano liquid chromatography coupled to high resolution tandem mass spectrometry (nanoLC-HRMS/MS) was used. Rat urine was prepared by simple dilution and incubation mixtures with pooled human liver S9 fraction by precipitation. Furthermore, the results concerning detectability using the new nanoLC approach were compared to those obtained by conventional ultra-high performance LC (UHPLC). In addition, the detectability of the compounds by standard urine screening approaches (SUSAs) routinely used by the authors with UHPLC-HRMS/MS, LC-MSn, and GC-MS was tested. Both NBOMes were extensively metabolized mainly by O-demethylation and conjugation with glucuronic acid (3,4-DMA-NBOMe) or oxidation of the tolyl group to the corresponding carboxylic acid (4-MMA-NBOMe). The developed nanoLC-HRMS/MS approach was successfully applied for identification of 38 3,4-DMA-NBOMe metabolites and 33 4-MMA-NBOMe metabolites confirming its detection power. Furthermore, the solvent saving nanoLC system showed comparable results to the UHPLC-HRMS/MS approach. In addition, an intake of an estimated low common user's dose of the compounds was detectable by all SUSAs only via their metabolites. Suggested targets for urine screening procedures were O-demethyl- and O,O-bis-demethyl-3,4-DMA-NBOMe and their glucuronides and carboxy-4-MMA-NBOMe and its glucuronide and N-demethyl-carboxy-4-MMA-NBOMe.