Low‐temperature plasma‐probe mass spectrometry based method for determination of new psychoactive substances in oral fluid

Abstract

The proposed LTP-MS-based method was promising in forensic and on-site applications to curb the abuse of NPSs.

Ambient ionization mass spectrometry applied to new psychoactive substance analysis

“…Therefore, the use of an isotopicallylabeled IS is important to ensure quantification over a good dynamic range or to give a reference for the absence of ion suppression when screening for the presence of a particular analyte in a complex matrix. In the case of NPS analysis using AIMS, the dynamic range has been proven to stretch up to three to five orders of magnitude; in earlier literature, the method's detection has mostly focused on the lower end of the concentration range, which is of high interest when dealing with NPS in biological matrices (Bianchi et al, 2019;Nie et al, 2016;Nollet & Munjanja, 2019;Wang et al, 2018).…”

“…The IS was added to the paper before analysis (Kennedy et al, 2018). Other sources, such as LTP and DESI, have been used to quantify cathinones and SCRAs in oral fluid, and LLOQs in the ng/ml range have been achieved (Bianchi et al, 2019;Wang et al, 2018). However, LTP-MS presented modest repeatability, and even though this was better with DESI-MS, the latter included a MEPS procedure that significantly increased the analysis time (15 min) and LLOQs were high (50-500 ng/ml).…”

“…Other thermal desorption‐based sources seem to be restricted to low‐polarity and volatile compounds; DART, ASAP and, to a larger extent, LTP (since it uses lower temperature), are primarily small‐molecule techniques, enabling effective ionization of compounds with molecular weights generally not exceeding one kDa (Hajslova et al, 2011). For instance, Wang et al (2018) analyzed phenethylamines, SCRAs, synthetic cathinones, and piperazines via LTP‐MS; higher molecular weight compounds, like SCRAs, were reported to perform poorly without thermal assistance (Wang et al, 2018). To increase the mass range of these ionization sources, increasing the temperature or the volatility of the analytes by derivatization has been shown to help.…”

“…Biomatrices contain other constituents that are found in much larger amounts than xenobiotics; these background species can generate chemical noise, reducing the signal‐to‐noise ratio (S/N), and can interfere with analyte signal (i.e., cause ion suppression or enhancement), thus compromising analytical sensitivity and reproducibility. These effects have mostly been observed with sources that allow ionization of molecules covering a wide range of molecular weights, like DESI, DART, and DAPPI (Birk et al, 2019; Jackson et al, 2010; Kuo et al, 2019; Lesiak et al, 2014a; Suni et al, 2011; Wang et al, 2018). Techniques that use atmospheric pressure photoionization (APPI) and APCI sources, like DAPPI and DSA respectively, usually have fewer matrix effects than ESI‐based techniques.…”

“…Most AIMS techniques demonstrated detection of NPS down to the low ng/ml range, though this is sometimes difficult to estimate since LODs are not always reported (Teunissen et al, 2017; Vandergrift & Gill, 2019; Vandergrift et al, 2018; Vircks & Mulligan, 2012). The analysis of cathinones and SCRA in oral fluid using LTP‐MS has shown LODs 10‐100 times greater than with LC‐MS/MS (Wang et al, 2018), and five to six times higher when using PSI‐MS to analyze mephedrone in fingerprints (Czerwinska et al, 2020).…”