MARVIN C. McMASTER, PhD, is a consultant and adjunct professor of chemistry at the University of Missouri–St. Louis, teaching courses on HPLC, GC/MS, and laboratory computing. He is a former researcher and product developer for DuPont, Kraft Foods, and Ciba-Geigy, and previously worked as a technical sales support specialist for instrument companies. Dr. McMaster is the author of HPLC: A Practical User's Guide and coauthor, with Christopher McMaster, of GC/MS: A Practical User's Guide (both from Wiley).