Recent studies have demonstrated the role of biofilms on the stability of drug residues in wastewater. These factors are pertinent in wastewater-based epidemiology (WBE) when estimating community-level drug use. However, there is scarce information on the biotransformation of drug residues in the presence of biofilms and the potential use of transformation products (TPs) as biomarkers in WBE.

The purpose of this work was to investigate the formation of TPs in sewage reactors in the presence of biofilm mimicking conditions during in-sewer transport. Synthetic cathinones (methylenedioxypyrovalerone, methylone, mephedrone) and phenethylamines (4-methoxy-methamphetamine and 4-methoxyamphetamine) were incubated in individual reactors over a 24 h period. Analysis of parent species and TPs was carried out using liquid chromatography coupled to quadrupole time-of-flight mass spectrometry (LC-QToFMS). Identification of TPs was done using suspect and non-target workflows.

In total, 18 TPs were detected and identified with reduction of β-keto group, demethylenation, demethylation, and hydroxylation reactions observed for the synthetic cathinones. For the phenethylamines, N- and O-demethylation reactions were identified. Overall, the experiments showed varying stability for the parent species in wastewater in the presence of biofilms. The newly identified isomeric forms of TPs particularly for methylone and mephedrone can be used as potential target biomarkers for WBE studies due to their specificity and detectability within a 24 h residence time.

最近的研究表明生物膜对废水中药物残留物稳定性的作用。在估算社区一级的药物使用量时，这些因素与基于废水的流行病学（WBE）有关。但是，关于在存在生物膜的情况下药物残留物的生物转化以及在WBE中潜在使用转化产物（TPs）作为生物标记物的信息很少。

这项工作的目的是研究在污水输送过程中在存在生物膜模拟条件的情况下污水反应器中总磷的形成。将合成的卡西酮（亚甲基二氧基吡咯烷酮，甲酮，甲吗啡酮）和苯乙胺（4-甲氧基-甲基苯丙胺和4-甲氧基苯丙胺）在各个反应器中孵育24小时。使用液相色谱和四极杆飞行时间质谱（LC-QToFMS）进行母体物种和TP的分析。TP的识别是使用可疑和非目标工作流程完成的。

总共检测到18种TP，并发现β-酮基的还原，去甲基化，去甲基化和羟基化反应是合成的卡西酮。对于苯乙胺，鉴定出N-和O-去甲基化反应。总体而言，实验表明在存在生物膜的情况下，废水中的母体物种具有不同的稳定性。新发现的TPs的异构形式，特别是对甲酮和甲氧麻黄酮，由于其特异性和可检测性，可在24小时内用作WBE研究的潜在靶标生物标志物。