Chapter 1 An Introduction to the Basic Principles and Concepts of Mass Spectrometry

Publisher Summary This chapter introduces the basic principles and concepts of mass spectrometry (MS). If a molecule can be converted into a gas phase ion, it can be interrogated by this technique. Making possible the study of proteins by MS required the development of methods to convert them into the gas phase ions and of techniques to separate the ions and detect them. The principles of these processes are discussed in the chapter. Amino acids, peptides, and proteins have several unique characteristics that make them particularly suitable to MS analysis. First, their ionizable functionalities render these molecules excellent candidates for electrospray ionization (ESI) and laser desorption (LD) ionization. Second, with the exception of isoleucine and leucine, the unique masses of 18 of the 20 common protein amino acids allow for identification on the basis of their mass alone. Third, the universal amide bond that links the amino acids means that the characterization of polymers of amino acids is not confounded with complications that arise from linkage heterogeneity, as is the case with carbohydrate characterization.