General Fragmentation of Bile Acid Derivatives

Many of the common major fragmentations were discussed by Bergstrom, Ryhage, and Stenhagen (5). Their results have been extended, with more comprehensive discussions of bile acid mass spectra (I, 12, 15, 18, 19). The fragmentation patterns of sterol derivatives are in many respects similar to those of the bile acids discussions of sterol mass spectra are given in (1, 11, 20-23). General reviews of steroid mass spectra may be consulted (1, 24,25). 

The following discussion is based on spectra of the bile acid derivatives listed in Table I. This is not a complete list of all published spectra but the results are representative of general fragmentation patterns. The molecular weights of bile acid derivatives can be calculated from the group contributions listed in Table II. This table also shows how the molecular weight changes when a hydroxy and/or keto bile acid methyl ester is converted into the derivatives. 

TABLE I. Bile Acid Derivatives Analyzed by Mass Spectrometry 

Configuration at C-5 Substituents Derivative Side chain Reference  

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