The Challenge of the Identification and Quantification of Transformation Products in the Aquatic Environment Using High Resolution Mass Spectrometry

Abstract

The environment is contaminated by a number of micropollutants and their degradation products, many of which still remain undetected. Nowadays, several European regulations require the inclusion of transformation products in environmental risk assessment and monitoring. In the last decade, intense efforts have been taken to recognize the identity, quantity, and toxicity of unknown transformation products. Liquid chromatography combined with mass spectrometry has become a key technique for environmental analysis, now allowing the development of screening, identification, confirmatory and quantitative methods for the trace analysis of polar compounds in complex environmental matrices. The combination of modern technologies comprising high resolution, high mass accuracy and mass fragmentation enables the identification of compounds without having the authentic standards or even the detection of unknown analytes. However, a reliable confirmation of proposed structures using NMR spectroscopy or available standards is still desirable. This chapter presents new analytical strategies to identify and quantify transformation products generated by human metabolism, microbial degradation, or other environmental breakdown processes. Various hyphenated mass spectrometric techniques used for structure elucidation, such as liquid chromatography coupled to time-of-flight mass spectrometry, quadrupole-time-of-flight and linear ion trap-Orbitrap hybrid mass spectrometry are presented on three case studies of pharmaceutical and pesticide transformation products in environmental matrices, such as wastewater and groundwater.