VITAMIN B (B^) 107 



The decrease in acidity from pH 4.28 to pH 5.2 increased the rate 

 of destruction of vitamin B to about the same extent as did the increase 

 in temperature from 100° to 110° C. in the experiments of Sherman 

 and Grose, and a change from pH 4.28 to pH 7.9 accelerated the de- 

 struction to a greater degree than did a change in temperature from 

 100° to 130° C. 



Sherman and Burton also found that this destruction of vitamin B 

 appears not to be due in any appreciable degree to oxidation, for sub- 

 stantially identical results were obtained whether the heating was done 

 in loosely covered flasks or under very strictly anaerobic conditions. 

 This was true both when experiments were conducted on tomato juice 

 at its natural acidity or at an alkahnity such that about one-half of 

 the vitamin B was destroyed in the experimental heating of 4 hours. 

 They suggested that the destruction of vitamin B in these cases 

 may have been due to an hydrolysis or intramolecular rearrangement, 

 and that in either case the destruction reaction was catalyzed by 

 hydroxyl ions. On both sides of neutrality, the rate of destruction was 

 a function of the pH of the medium in which the vitamin B was dis- 

 solved. 



Kinnersley and Peters (1928) reported that while alkali is destruc- 

 tive to the vitamin certain other factors appear to accelerate the inacti- 

 vation. Whereas a less pure preparation (activity 1.0 milligram) was 

 kept in 99 per cent alcohol made more acid than pH 2 for 3 years at 

 room temperature with no apparent alteration in activity, the purest 

 preparations have been found to lose activity at room temperature 

 in a few weeks under these conditions. In alkaline alcoholic solutions 

 the vitamin was completely inactivated. They confirmed the stability of 

 vitamin B to oxidizing agents in acid solution. Heating with 5 per cent 

 nitric acid, or with potassium permanganate in acid solution or hydro- 

 gen peroxide in acid solution did not appreciably inactivate the vitamin, 

 whereas hydrogen peroxide in alkaline solution at room temperature 

 produced rapid destruction. Guha and Drummond (1929) reported 

 upon the stability of a comparatively concentrated preparation of vita- 

 min Bi (charcoal concentrate) upon heating at different hydrogen-ion 

 concentrations for dififerent periods of time. Boiling for 24 hours at 

 pH 1 did not cause any appreciable inactivation, while at pH 5 it de- 

 stroyed about half ; boiling for 1 hour at pH 9 destroyed about half, 

 while shorter periods of boiling resulted in correspondingly less de- 

 struction. They confirmed the finding of McCoUum and Simmonds 

 (1918), Peters (1924), and Levene (1928) that nitrous acid does not 

 destroy vitamin Bi (antineuritic). Neither their picrolonic acid filtrate 



