Mass spectrometry functional group fragmentation

An example of how information from fragmentation patterns can be used to solve structural problems is given in Worked Example 12.1. This example is a simple one, but the principles used are broadly applicable for organic structure determination by mass spectrometry. We ll see in the next section and in later chapters that specific functional groups, such as alcohols, ketones, aldehydes, and amines, show specific kinds of mass spectral fragmentations that can be interpreted to provide structural information. 

High performance spectroscopic methods, like FT-IR and NIR spectrometry and Raman spectroscopy are widely applied to identify non-destructively the specific fingerprint of an extract or check the stability of pure molecules or mixtures by the recognition of different functional groups. Generally, the infrared techniques are more frequently applied in food colorant analysis, as recently reviewed. Mass spectrometry is used as well, either coupled to HPLC for the detection of separated molecules or for the identification of a fingerprint based on fragmentation patterns. ... 

In the 1950s, Benyon, Biemann and McLafferty clearly demonstrated the chemistry of functional groups in directing fragmentation, and the power of mass spectrometry for organic structure determination began to develop. 

The role of functional groups in directing molecular fragmentation, and the value of mass spectrometry in elucidation of the structure of organic compounds was clearly demonstrated by Biemann [28], Beynon [29], and McLafferty [30]. 

Mass spectrometry of organic molecules has become well established in recent years and both the recording of spectra and the fragmentation patterns of functional groups have been comprehensively discussed (14, 19, 33, 126, 142). In the last 2 3 years the study of the behavior of organometallic compounds in the mass spectrometer, previously a neglected... 

These fragmentations serve to illustrate many of the major types. The driving force behind all of them is the formation of stable cations and radicals. Fragmentations of functional groups that have not been covered here are often similar to those described earlier. Although this has been only a very brief introduction to mass spectrometry, the power and utility of this technique should be apparent. 

Mass spectrometry (MS), also covered in this chapter, is not a spectroscopic technique, because it does not measure absorption or emission of light. A mass spectrometer bombards molecules with electrons and breaks the molecules into fragments. Analysis of the masses of the fragments gives the molecular weight, possibly the molecular formula, and clues to the structure and functional groups. Less than a milligram of sample is destroyed in this analysis. 

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