This chapter aims to describe advances in analytical instrumentation and methods for the analyses of herbicides and their degradation products and to assess their impact on major findings of broad surveys of herbicides in water conducted by the U.S. Geological Survey(USGS) over the last two decades. Standards for water purity have been set and continually revised by governments as new contaminants that may impact human health are identified. These water-purity standards have brought continued improvement in water quality of existing water sources by reducing the amount of pollution in drinking water, treating wastewater, diverting wastewater discharge from drinking-water supplies, implementing new filtration practices, and other innovative techniques. It is vital that state-of-the-art instrumentation for analyzing organic contaminants continually be introduced into the marketplace the advancement of analytical instrumentation has given scientists the capability to continually broaden their studies of the fate of herbicides and their degradation products over the last two decades. Studies by many scientists have continually expanded the knowledge of the occurrence, persistence, and transport of herbicides and their degradation products in the hydrologic environment.
