Owing the their outstanding sensitivity, gas chromatography (GC) and mass spectrometry (MS) are fast becoming indispensable analytical techniques used in clinical chemistry. This book is a guide to everyday work with these analytical methods. It discusses the fundamental principles of analysis by GC/MS along with the use of GC/MS in drug screening and the detection of pollutants in industrial medicine, and it provides extremely useful guidelines to the organization and costing of GC/MS analysis in the clinical laboratory.