201 
A SIMPLE METHOD FOR THE PREPARATION 
AND DETERMINATION OF LECITHIN 
BY 
HERBERT E. ROAF, M.B., Toronto 
JOHNSTON COLONIAL FELLOW, UNIVERSITY OF LIVERPOOL 
AND 
E. S. EDIE, M.A., B.Sc, Edinburgh 
THE majority of the methods which have hitherto been described for the 
isolation of lecithins from the tissues are based on the method originally 
designed by Diakonow, 1 and modified by Hoppe-Seyler. 2, This consisted 
in removing the fats by repeated extraction of the fresh material with ether until the 
last ethereal extract possessed only a slightly yellow colour. The residue of material 
after extraction with ether was next extracted with absolute alcohol at 50-60° C, 
and the filtered extract was evaporated down to the consistency of a syrup, which 
was taken up in ether, decanted, filtered, and the filtered ethereal solution was evapo- 
rated down. The residue from the ether was next dissolved in as small a quantity of 
absolute alcohol as possible, and the filtered solution exposed for some hours in a 
freezing mixture to a temperature of 5-10 0 , when the lecithin was precipitated 
out of solution. 
In this method there is an enormous loss of the available lecithin, not only in 
the first washings of the tissue with ether, for lecithin has quite a high solubility in 
ether, but also in the failure of a large part of the lecithin being thrown out from 
the cold alcohol in the freezing mixture. 
While the method was therefore useful in obtaining a small yield of compara- 
tively pure lecithin for purposes of investigation, it is extremely wasteful, and is 
useless as a method of determination of the amount of lecithin in any given tissue. 
So much so that most observers have been content to estimate the percentage of 
lecithin from determinations of the amount of one of its constituents, usually either 
the phosphorus as magnesium pyrophosphate or the neurin as the platinum salt. 
As a means of combating the loss in the ether washings, Gilson ! recommended 
that the united ethereal extracts should be separated from the ether by distillation, 
I. Hoppe-Seyler's Med. diem. Untersuch, 1867. 
2. Handbuch d. physiol-u-path . chem. Analyse, Berlin, 1893, S. 84. 
3. Zeitsch f. physiol. chemie (1888)", Bel. xii, S. 588. 
BI 
