An attempt to separate vitamin B2 from vitamin B1 in yeast and a comparison of its properties with those of the antineuritic vitamin B1

YEAST contains both constituents of the " water-soluble B " vitamin, vitamins B and B2, in abundance, and seeing that the antineuritic (vitamin B1) con- centrate prepared by the method of Peters [1924] is free from vitamin B2 [Chick and Roscoe, 1927] our first endeavour towards the separation of this vitamin was to scrutinise every stage of the process to find where the dis- appearance occurred.Our method has been that of Kinnersley and Peters [1925, 1927] with a few modifications.10-12 kg. of pressed, brewery yeast were washed three or four times with cold tap water.The pressed yeast was puddled with water to the consistency of cream, filtered on a Gooch filter, using slight suction, and finally sucked dry or pressed in a hand press, this process being repeated three or four times until the filtrate was of a pale straw colour.After removal of a small sample for deterftination of the dry weight, the washed, pressed yeast (in the proportion of 1 kg.pressed, or 200 g.dry, yeast to 2-3 litres water) was thrown into boiling tap water containing 0-02 % acetic acid; this was raised again to the boiling point and allowed to boil for 5 minutes and filtered.This extract ("Fraction 5") about 20-30 litres in volume, was then treated with 25 % lead acetate solution till no more precipitate was formed (ca.55-80 cc. per litre of extract), the whole allowed to stand overnight and then filtered.To the filtrate ("Fraction 4") baryta, at first solid and then as saturated solution, was added, till no more precipitate formed.As the re- sulting solution is alkaline, filtration was carried out at once and the filtrate acidified with strong H2SO4 until a PH of about 4*0 was reached (using the indicator bromocresol green or Congo red).Th-e solution, heated to assist agglutination of the precipitated BaSO4, was filtered, and to the filtrate Hopkins's reagent (10 % solution of HgSO4 in water containing 70 cc.H2SO4 per litre) was added to the point of most complete precipitation (25-50 cc. per litre of filtrate).In order to remove any traces of lead and mercury that might be present, H2S was passed through the filtrate to saturation and the whole allowed to stand several hours in corked bottles; on heating the solution,