Concepts of Tandem Mass Spectrometry

Tandem mass spectrometry (MS/MS) has attained an enviable status as an analytical tool to identify and quantify compounds in complex mixtures. MS/MS refers to the coupling of two stages of mass analysis, either in time or space. Of all the ionization techniques, only electron ionization (El) provides abundant sttuctural information. To obtain additional structure-specific information by other ionization techniques, it has become essential to perform MS/MS experiments [1,2]. MS/MS was first used in the late 1960s [3]. Since that time, its applications and popularity have continued to grow. Its major contributions are in the fields of structure elucidation of unknown compounds, identification of compounds in complex mixtures, elucidation of fragmentation pathways, and quantification of compounds in real-world samples. In recent times, several new generations of instruments have become available for tandem mass spectrometry applications. Basic concepts of tandem mass spectrometry and an account of these new developments are presented in this chapter. Additional reading material is listed at the end of the chapter. 

Explain the basic concepts of tandem mass spectrometry. 

This section deals with some general principles of tandem mass spectrometry and its applicability to quantitative analysis. The MS/MS acronym is used in this book as a general term for aU tandem mass spectrometry techniques. More detailed descriptions of how the principles are exploited in practice for the various instrumental types are given in later sections of this chapter. The general concept of tandem mass spectrometry in qualitative (structural) analysis is that additional chemical information, over and above that contained in a conventional onedimensional mass spectrum, can be obtained by examining the connectivity relationships among some or all of the ions in that mass spectrum. The connectivities arise as a result of the dissociation reactions that lead to the fragment ions in a mass spectrum, e.g. ... 

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