Phenoxyacetic herbicides, particularly 2,4-D and 2,4,5-T, have played a central role in modern agriculture, although their use has also sparked significant environmental and toxicological controversies. This book provides a comprehensive overview of the main aspects related to these compounds, including their chemistry, mechanisms of action, environmental behavior, toxicity, international regulation, and analytical monitoring strategies.The book presents an up-to-date overview of conventional methodologies used for their determination, as well as new tools based on molecular fluorescence, solid-phase fluorescence, organized systems, nanotechnology, and fluorescent nanosensors. In addition, it incorporates approaches related to green analytical chemistry and the sustainable monitoring of emerging contaminants.