VITAMIN RESEARCH 



vitamins yet to be discovered are destined to have lesser nutritional 

 significance for human welfare and that the vitamins which are re- 

 quired to check the nutritional plagues of mankind have already been 

 discovered and produced. Nevertheless, he recognized that there 

 may be exceptions, particularly in the case of obscure diseases. Un- 

 doubtedly, chemists and nutritionists must cooperate scientifically 

 for many years on the problems of the discovery of new vitamins. 



On the Isolation of Vitamins 



The isolation of a vitamin from the natural material in which it 

 exists is essentially a chemical problem of the same nature as the older 

 problems on the isolation of an alkaloid or a glycoside, but with at 

 least two important dilTerences. One of these differences is that vita- 

 mins generally occur in quantities amounting to a few parts per million 

 of the natural material, whereas the common alkaloids and glycosides 

 are found frequently in quantities amounting to a few parts per 

 hundred. The greatest difficulties in vitamin isolation might be said to 

 lie in the region of converting the natural materials with a few parts per 

 million of the substance to a concentrate containing a few parts of the 

 substance per hundred. New techniques and new procedures are 

 frequently devised to surmount the difficulties in making such a puri- 

 fication. The isolation of trace substances in milligram or gram quanti- 

 ties requires the processing of hundreds of pounds of the natural ma- 

 terial. A second important diff"erence in the isolation procedure is 

 the necessity for countless biological assays throughout the whole 

 isolation work to show the investigator the location (and loss !) of the 

 vitamin in the fractionation. 



Pioneering researches on the isolation of a vitamin are very costly 

 and time-consuming. It has been said (69) that the first gram of pure 

 natural thiamin must have cost an aggregate of several hundred 

 thousand dollars. Eight years transpired between the first success in 

 isolating this vitamin m 1926 by Jansen and Donath (21) and the work 

 of Williams, Waterman, and Keresztesy (70) m 1934, which resulted 

 in greatly improved yields, so that a sufficient quantity of the pure 

 vitamin could be made available for its structure determination. It 

 took five years in Kogl's laboratory at the University of Utrecht in 

 Holland to work out the pioneering methods which yielded seventy 



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