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.

水生环境中的有机微污染物（Organic micropollutants, OMPs）对传统水处理工艺构成严峻挑战。高级氧化工艺（Advanced oxidation processes）例如紫外光解（UV photolysis），是去除OMPs的有效手段。然而此类工艺往往会生成未知的转化产物（transformation products, TPs）。基于高分辨质谱（High-resolution mass spectrometry, HRMS）的非靶标分析（non-target analysis, NTA）常被用于大规模化学品筛查，但也面临多项特定挑战：目标化合物浓度极低、缺乏对应参考标准，且在用于TP鉴定时需依托复杂的数据分析流程。本文详述了一套整合自动化光降解装置、HRMS与先进NTA技术的完整分析流程，用于研究紫外光解相关过程及其生成的TPs。在一项案例研究中，四种药物成功实现降解；研究人员通过本工作开发的互补分析方法，从复杂样品基质中有效筛选出38个NTA特征峰并鉴定为TPs。所鉴定的TPs结构多样且绝大多数为新型产物。半定量分析结果表明，这些TPs可解释母体化合物去除量的可观比例。本研究开发的分析流程为系统性全面解析水环境乃至其他场景中的转化过程迈出了关键一步。本次公开的数据分析工具与数据集可进一步丰富转化产物数据库与相关算法，并为通用的非靶标分析研究提供支撑。