Identification of transformation products (TPs) of emerging pollutants is challenging, due to the vast number
of compounds, mostly unknown, the complexity of the matrices and their often low concentrations, requiring
highly selective, highly sensitive techniques.Wecompile background information on biotic and abiotic
formation of TPs and analytical developments over the past five years. We present a database of biotic or
abiotic TPs compiled fromthose identified in recent years.We discuss mass spectrometric (MS) techniques
and workflows for target, suspect and non-target screening of TPs with emphasis on liquid chromatography
coupled to MS (LC-MS). Both low- and high-resolution (HR) mass analyzers have been applied, but
HR-MS is the technique of choice, due to its high confirmatory capabilities, derived fromthe high resolving
power and the mass accuracy in MS and MS/MS modes, and the sophisticated software developed.