Analysis of new psychoactive substances (NPs) in oral fluid samples by high-resolution mass spectrometry and in vitro metabolism study

Abstract

The number of new psychoactive substances (NPS) has grown exponentially in recent years. Due to their high capacity to generate effects in low doses, the number of intoxications has grown along with the consumption. In Brazil, epidemiological reports involving NPS consumption are not available. All of the published data involves single or small group intoxication cases. In most of the cases, these NPS are detected in biological samples in order of ng/mL (or even less) quantities, requiring sensitive techniques to detected them. Besides that, NPS metabolites generated after their consumption are not always known; however, they can help to develop more selective methodology and/or facilitate the identification of the precursor substance in larger detection windows. One of the ways to study the human metabolism is to use human liver microsome (HLM), or Human Liver Hepatocytes (HLH) in the presence of the chosen substance and cofactors intending to mimic the biological environmental, but in a reduced medium. Objetives: 1) analyze oral fluids samples collected in Brazil using untargeted method based on liquid chromatography tandem high-resolution mass spectrometry (LC-HRMS). These analyses have the purpose to cover a greater number of NPS than it is possible to detect by our MS/MS homemade library. 2) study NPS in vitro metabolism using human liver microsome and human liver hepatocytes. Material and method: The oral fluid samples collected in Brazil will be sent to the Center for Forensic Science Research and Education (CFSRE) laboratory. These samples will be extracted according to the CFSRE validated protocol, and analyzed by a liquid chromatography liquid chromatography-quadrupole timeofflight mass spectrometry. From the results obtained by the oral fluid samples, the NPS detected will be targeted for the in vitro metabolism study using HLM and HLH- if no previous studies have been published. The HLM and HLM incubation samples will be analyzed using high resolution mass spectrometry (Sciex TripleTOF® 5600+ QTOF). Expected results: From the oral fluid samples already collected in Brazil and analyzed by triple quadrupole mass spectrometry, it is expected to expand the knowledge on the consumption of this new and important group of drugs of abuse in the festival environment in order to establish the main substances in circulation, using now a high-resolution mass spectrometry. From the studies of in vitro metabolism, it is expected to predict the toxicokinetics of the most incident substances in this context, as well as structural elucidation of their main metabolites. (AU)