A review on the latest frontiers in water quality in the era of emerging contaminants. A focus on perfluoroalkyl compounds

Water quality is continuously deteriorating due to various drivers of change, including rapid urbanization, industrial development, inadequate sanitation facilities, and climate change. Furthermore, the detection of newly monitored emerging contaminants, which are not always fully regulated, has turned water pollution into a "time bomb" on the verge of exploding. While laboratory-based methodologies offer significant advantages, such as high sensitivity, accuracy, and selectivity, the steady growth of sensors and soft sensors for on-line and on-site quality monitoring purposes cannot be overlooked. This review focuses on sensor innovations over the past five years, providing an in-depth comparison between classical methods and novel advanced technologies. It also explores current strategies for controlling emerging contaminants, potential regulation limits, and solutions to overcome the transboundary challenges of water quality management. Special attention is given to a class of emerging contaminants, the perfluoroalkyl compounds (PFAS), which are ubiquitously found in water matrices. For them, a comparison between traditional laboratory-based methods and sensor technologies is presented to evaluate their reliability and potential for future off-lab monitoring applications.