140 IV. BILE PIGMENTS 



the fluorescence of urobilln-zinc can be readily differentiated from 

 the green fluorescence of other substances or drugs which may be 

 found in urine or feces {e.g., atebrin). As in the porphyrin series the 

 similar urobilin-copper complexes do not fluoresce. 



TABLE IX 



Absorption Spectra of Me.sohilene-(b) and Its Compounds 



Band position measured by Pruckner and Stern spectrophotometrically, by Lemberg 

 with the Hartridge Reversion Spectroscope. Lemberg and co-workers (1713) 

 found the position of the main band 492.5 m^t in the visual spectrophotometer, 

 490.0 mfi in the ultraviolet spectrophotometer. 



Sample amorphous, but evidently nearly pure. Heilmeyer (2390; 1213, p. 209) 

 observed far lower and very varying values (11.2 to 32) for «mlM, probably because 

 of partial dissociation and (in aqueous solution) formation of a colloidal solution 

 in the medium which did not contain excess HCl. 



In the presence of ammonia: 506 m/z. 



6.3. Tetrahydromesobilane (Stercobilinogen, Urobilinogen B) 

 and Tetrahydroniesobilene-(b) (Stercobilin) 



6.3.1. Structure. Tetrahydromesobilene-(b) was isolated from 

 feces as pure crystalline hydrochloride by Watson {2970,2972-297 If) 

 and called stercobilin. The first analyses indicated a formula with 

 eight oxygen atoms. Heilmeyer and Krebs {1218) claimed that 

 reduction of stercobilin yielded mesobilane. Watson found, however, 

 that no crystalline mesobilane could be obtained by reduction of 

 stercobilin, and Lemberg {1677) first showed clearly that sterco- 

 bilinogen differed from mesobilane. By ferric chloride, stercobilinogen 

 was oxidized only to stercobilin, while mesobilane yielded mesobili- 

 violin and mesobiliverdin. This was later confirmed by Watson 

 {2981) and Fischer {823). To explain these results Lemberg in 1934 

 assumed a mesobilenedione formula which was based on the 0$ 

 formula. Again the analyses of the incompletely purified substance 



