Mass spectrometry typical small fragments

Typical fragmentation of both types of base involves the loss of small neutral molecules such as HCN, CO, and CH3CN, as well as some extensive rearrangements in aromatic compounds. The most common derivatization, silylation under normal conditions (TMSC, HMDS/TMSC, BSA, or BSTFA/TMSC, V, 20 min - 2 hr), with or without pyridine as a solvent and base catalyst, usually leads to the enolic forms of the bases via the corresponding silyl ether. The persilylated derivatives are volatile enough to be used in gas chromatography-mass spectrometry (GC-MS). This enhancement of volatility compared to that of the free bases is the key factor making GC-MS a widely used analytical method in this area. 

The high sensitivity and selectivity of mass spectrometry (MS) facilitates the identification and structural analysis of small quantities of carotenoids that are typically obtained from natural product samples such as plants, animals, or human serum and tissue. Structural information from the abundant fragmentation is provided by classical ionization methods, such as electron impact (El see Sect. 4.3.1) and chemical ionization (Cl see Sect. 4.3.1), but molecular ions are not always observed. Recent advances in soft ionization techniques, such as fast... 

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