The evolving nature of new psychoactive substances (NPS) - often referred to as 'legal highs', 'designer drugs' or 'bath salts' - presents an evolving challenge for toxicologists. Apart from the detection and identification of these compounds, further analytical challenges may arise from the presence of possible metabolites or degradation products which may have to be considered when devising an analytical strategy. Whilst there has been some stability research for some more established drugs of abuse and medicinal products, data on emerging NPS are less abundant. In order to address this need, 13 NPS (4-MEC, MDAI, methoxetamine, 5-MeO-DALT, 6-APB, MPA, 5-IAI, MDAT, 2-AI, AMT, 25C-NBOMe, AH-7921, 5-MAPB) were spiked in blood and plasma and kept at room temperature (20-23 °C). Detection and identification of the suspected breakdown products were carried out by high performance liquid chromatography with diode-array detection (HPLC-DAD), liquid chromatography-tandem mass spectrometry (LC-MS/MS), and ultra high performance liquid chromatography with high mass accuracy quadrupole time-of-flight mass spectrometry (UHPLC-Q-TOF-MS). 4-MEC became undetectable in blood within 14 days with a corresponding loss of 54% in plasma. A breakdown product was identified as dihydro-4-MEC which was also found in vivo in a case work sample. Storage of AMT led to a range of potential breakdown products which were also found in vivo. The remaining substances were found to be stable for at least 21 days in blood and plasma. This is the first time stability data have been published for these emerging substances and showed that additional compounds found during forensic casework were potential metabolites rather than instability products. In particular, presumptive metabolites of 25C-NBOMe and AH-7921 are presented.

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Identification of soluble microbial products (SMPs) released during bacterial metabolism in mixed cultures in bioreactors is essential to understanding fundamental mechanisms of their biological production. SMPs constitute one of the main foulants (together with colloids and bacterial flocs) in membrane bioreactors widely used to treat and ultimately recycle wastewater. More importantly, the composition and origin of potentially toxic, carcinogenic, or mutagenic SMPs in renewable/reused water supplies must be determined and controlled. Certain classes of SMPs have previously been studied by GC-MS, LC-MS, and MALDI-ToF MS; however, a more comprehensive LC-MS-based method for SMP identification is currently lacking. Here we develop a UPLC-MS approach to profile and identify metabolite SMPs in the supernatant of an anaerobic batch bioreactor. The small biomolecules were extracted into two fractions based on their polarity, and separate methods were then used for the polar and nonpolar metabolites in the aqueous and lipid fractions, respectively. SMPs that increased in the supernatant after feed addition were identified primarily as phospholipids, ceramides, with cardiolipins in the highest relative abundance, and these lipids have not been previously reported in wastewater effluent.

This study investigated the performance of a submerged anaerobic membrane bioreactor (SAMBR) fed with synthetic wastewater (544 ± 22 mgCOD/L) operating at different hydraulic retention times (HRTs-12 h, 8 h, 6 h, 4 h, 2 h, and 1 h) at both steady state, and under transient load conditions (2 and 1 h), and the SMPs produced under these conditions. COD removal at decreasing HRTs (12 h, 8 h, 6 h, 4 h, and 2 h) was high (>94%), but decreased to 80% when operating at 1 h HRT. VFAs accumulated when the HRT was decreased to 2 h and 1 h, accounting for 69% and 89% of the effluent COD, respectively. Effluent SMPs accounted for an average of 14±2 mgCOD/L at steady state, but this fluctuated more during transient conditions (12±6 mgCOD/L). The COD *Revised Manuscript (clean for typesetting) Click here to view linked References

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