. A Liquid Chromatography-Mass Spectrometer (LC-MS) is requested for this Shared Instrumentation Grant application. The instrument consists of a High Performance Liquid Chromatography system coupled to an orthogonal time-of-flight ESI/APCI mass spectrometer, and is to be set up as direct "open-access" instrumentation to researchers (graduate students, postdoctoral fellows, undergraduates, and research technicians). The ability to chemically characterize complex molecule samples lies at the heart of various disciplines, including the chemical sciences in particular. The users of this instrumentation will primarily consist of researchers engaged in the synthesis of novel organic and organometallic molecules that are of importance to biology and human medicine. A versatile LC-MS instrument equipped with an autosampler and "walk-on" access software for student operation will significantly advance several exciting NIH-funded research projects. Each of these efforts depends on the rapid structure elucidation of the molecular products formed in each synthetic process and is therefore directly dependent on the molecular analysis techniques immediately available to the researcher. The availability of open-access LC-MS instrumentation, which allows for immediate access to mass profile data of reactions as they are being performed, will not only increase the rate at which reactions can be performed, but also enhance the accuracy with which each reaction can be scientifically evaluated. This would greatly accelerate the rate at which novel discoveries can be made in the preparation of molecules of biological importance. The associated NIH-funded projects include, but are not limited to, the development of new synthetic methods for the preparation of natural and non-natural molecules of biological and therapeutical interest. These goals involve both target- and diversity-oriented synthesis of novel anti-bacterial, antiviral and antitumor agents, various natural and non-natural products, molecular probes for steroid receptors, radiopharmaceuticals for breast tumor imaging, and small molecule protein mimics for biomedical sensor arrays. PUBLIC HEALTH RELEVANCE: Several NIH-funded investigators in the Department of Chemistry at the University of Illinois seek funding to purchase an instrument for combined liquid chromatography/mass spectrometry. Such an instrument will significantly enhance our ability to analyze organic reactions, ultimately leading to much more rapid progress toward our project goals.