Tracking pharmaceuticals and transformation products in environmental matrices using quadrupole time-of-flight mass spectrometry: a systematic review

The increasing release of pharmaceuticals into ecosystems necessitates tracking both parent compounds and their transformation products (TPs). This systematic review summarizes recent advancements in quadrupole time-of-flight high-resolution mass spectrometry (Q-TOF HRMS) for tracing pharmaceuticals and TPs across diverse environmental and biological matrices. A total of 345 records were identified through the Web of Science Core Collection search, and 77 studies met the predefined eligibility criteria and were included in the final review. The review highlights Q-TOF HRMS principles, non-targeted and suspect screening strategies, and applications in aquatic systems, agricultural plants, animal products, and biosolids. Emphasis is placed on identifying unknown TPs and distinguishing biologically generated metabolites from abiotic transformation products. Sampling and pretreatment strategies for complex matrices, chromatographic separation, ion mobility-derived collision cross sections, and workflows supporting comprehensive screening are discussed. Despite these advances, identification reliability remains limited by scarce reference standards and data processing challenges, which constrain confident feature filtering and downstream semi-quantification, underscoring the need for methodological optimization and computational tools to enhance detection and structural elucidation of environmental TPs.