MARVIN C. MCMASTER, PHD, is a consultant as well as an Adjunct Professor of Chemistry at the University of Missouri— St. Louis. Dr. McMaster has served as a researcher and product developer for DuPont, Kraft Foods, and Ciba-Geigy. Among his other publications, Dr. McMaster is author of LC/MS: A Practical User's Guide and coauthor of GC/MS: A Practical User's Guide (both published by Wiley).