ULTUAVIOLET ABSOKFTION SPECTRA 



191 



th(; rrfrioM 24(XJ 2800 A (e = 20,(K)0j and a second weaker band at 3400- 

 3800 A (Fif^. 5-24) (Jacoh.son and Simpson, 1940; Totter, 1944; Mowat el 

 al., 1948; Ilitchinj^s and Klion, 1949; Cain el al., 1948; Elion el a/., 1950;. 



200 220 240 260 280 300 320 340 360 380 400 420 440 460 480 500 



WAVE LENGTH, m/Z 



Fi<;. 5-23. Absorption spectra of riboflavin in solutions at different pH values. {Dag- 

 lish el al., 1948.) 



800 



600 



^S 



400 



200 



240 



440 



290 340 390 



AAVE LENGTH, m_// 



Fio. .5-24. .\bsorption spoctruni of xanthopterin. I, in 0.1 .V .sodium hydroxide, .50.1 

 mg/liter; II, in glacial acetic acid, 49.4 nig/liter. {Totter, 1944.) 



VITAMINS 



Reduced nicotinamide iodomelliylate has a strong absorption band at 

 345 mn which (lisapp(!ars upon o.xidation (Karrer and Warburg, 1936; 



