E. M. THURMAN is an organic geochemist at the U.S. Geological Survey with twenty years of research experience in the environmental chemistry of water and soil, as well as extensive experience in sorption chromatography and XAD and SPE resin technology. Dr. Thurman has published research papers on the theory of XAD resins, applications of SPE in environmental chemistry, drug applications of SPE, and isolation of natural products by SPE and ion exchange. He is the coauthor of Immunochemical Technology for Environmental Applications, the coeditor of Herbicide Metabolites in Surface Water and Grou...