Fragmentation pathways of ions

Let us discuss again the primary fragmentation pathways of ion ABXY+ ... 

Although convenient at first sight, the lack of fragment ion peaks in FI spectra also means a lack of structural information. If data beyond a mere estimate of the elemental composition based on the isotopic pattern are asked for, then tandem MS employing collision-induced dissociation (CID, Chap. 9) is the preferred standard of stmcture elucidation. Fortunately, the fragmentation pathways of ions in CID are the same as in EI-MS (Chap. 6). 

Example The fragmentation pathways of ions of Trocade , an anti-rheumatoid drug, [trocade+H]", m/z 437, were elucidated by sequential tandem MS up to MS on a QqLIT instrument (Fig. 9.24). The protonated molecule first eliminates hydroxylamine, 33 u, to yield the acylium ion fragment at m/z 404, which in turn cleaves off the imidazolidinedione substituent at the a-carbon prior to loss of CO from the fragment ion at m/z 262 [115]. 

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