Comprehensive Mass Spectrometry Workflows to Systematically Elucidate Transformation Processes of Organic Micropollutants: A Case Study on the Photodegradation of Four Pharmaceuticals

Organic micropollutants (OMPs) in the aquatic environment challenge conventional water treatment processes. Advanced oxidation processes, such as UV photolysis, serve as effective strategies to remove OMPs. However, these often yield unknown transformation products (TPs). High-resolution mass spectrometry (HRMS)-based non-target analysis (NTA) is commonly used to screen large numbers of chemicals but faces specific challenges such as low concentrations of compounds of interest, lack of reference standards, and the need for sophisticated data analysis workflows when used for TP identification. This article describes comprehensive workflows to study UV photolysis-related processes and the resulting TPs, by combining an automated photodegradation setup and HRMS and advanced NTA approaches. Four pharmaceuticals were successfully degraded in a case study, and 38 NTA features were effectively prioritized from complex sample matrices and identified as TPs through complementary approaches developed in this work. The identified TPs were structurally diverse and mostly novel. Semi-quantitation suggested that the TPs explained a relevant part of the parent removal. The developed workflows are a step toward systematic comprehensive analysis of transformation processes in water and beyond. The openly available data-processing tools and data enhance transformation data repositories and algorithms and support NTA studies in general.

水环境中的有机微污染物（OMPs）对常规水处理工艺构成挑战。高级氧化工艺（如紫外光解）是去除有机微污染物的有效手段，但此类工艺往往会生成未知转化产物（TPs）。基于高分辨质谱（HRMS）的非靶标分析（NTA）常被用于大规模化学品筛选，但该方法存在特定局限：目标化合物浓度偏低、缺乏对照标准品，且用于转化产物鉴定时需依托复杂的数据分析流程。本文结合自动化光降解装置、高分辨质谱与先进非靶标分析方法，构建了一套用于研究紫外光解相关过程及其生成转化产物的完整分析流程。案例研究中，四种药物类化合物成功实现降解；本研究通过开发的互补分析策略，从复杂样品基质中有效筛选出38个非靶标分析特征峰，并将其鉴定为转化产物。所鉴定的转化产物结构多样，且多数为新型产物。半定量分析结果显示，转化产物可解释母体化合物去除量的可观占比。本研究构建的分析流程，为水环境及其他相关领域的转化过程系统性全面分析迈出了关键一步。本次研究公开的数据分析工具与数据集，可进一步完善转化数据资源库与算法体系，同时为非靶标分析相关研究提供通用支持。