This reference summarizes the theory, instrumentation, and application of mass spectrometry and atmospheric pressure ionization to screen, evaluate, and improve the performance and quality of drug candidates. It covers: recent advances in combinatorial chemistry, molecular biology, bioanalysis automation, and computing; cassette dosing; the utilization of liquid chromatography/mass spectrometry (LC/MS) in chemical library characterization, combinatorial chemistry, drug transport, and in vivo microdialysis; reliable methods of sample preparation and handling; novel strategies to determine and characterize metabolite structures; the impact of absorption, distribution, metabolism, and elimination properties on drug discovery.

INTRODUCTION
The Demand for Drug Discovery Today
The Impact of Atmospheric Pressure Ionization
INSTRUMENTATION
A Mass Spectrometry Primer
EXPERIMENTAL STRATEGIES
Ion Chemistry and Fragmentation
The LC/MS Experiment
Sample Preparation and Handling for LC/MS in Drug Discovery
APPLICATIONS
Mass Spectrometry in Combinatorial Chemistry
Drug Hydrophobicity and Transport
The Mass Spectrometer in Drug Metabolism
Mass Spectrometry-Assisted Applications of Stable-Labeled Compounds in Pharmacokinetic and Drug Metabolism
Studies
Cassette Dosing in Drug Discovery
Applications of Microdialysis/Mass Spectrometry to Drug Discovery
Future Directions for Mass Spectrometry in Drug Discovery
Index