MASS SPECTROMETRY AND FERRIC CHLORIDE OXIDATION APPLIED TO UROBILINOID STRUCTURES

The mass spectra of a large number of bilirubinoid and urobilinoid substances have been measured. The time-varying intensities in the parent ion regions of these materials have been scrutinized and interpreted in terms of oxidation and reduction reactions taking place prior to volatilization and electron impact. Structural and stereochemical implications of the ferric chloride oxidation method for the urobilinoids are discussed. Correlations of the results of this method with mass spectrometric data provide a basis for the categorization of urobilinoids into three classes: Dipyrrolinone (e.g. d-urobilins, mol wt 588 and 590), pyrrolinone-pyrrolidone (e.g., half-stercobilin mol wt 592), and dipyrrolidone (e.g., stercobilin mol wt 594). © 1969.