52 CHOLINE 



cultures of Bacillus prodigiosus,-" Shigella alkalescens,-^ Proteus vulgaris,^^ 

 and many other organisms. 



There is a wide distribution of chohne phosphohpids throughout the 

 plant world. Ducet-^- -* examined seedlings of soybean, l^arley, and pea and 

 other young plants and concluded that synthesis of choline occurs in 

 rapidh' growing tissues, such as leaf buds. He believed that giycerylphos- 

 phor^dcholine is an intermediate in the synthesis of lecithin. The occur- 

 rence of small amounts of free choline was ascribed to the presence of 

 lecithinase. 



VII. Estimation 



WENDELL H. GRIFFITH and JOSEPH F. NYC 



A. CHEMICAL PROCEDURES 



Chemical procedures for the quantitative determination of choline in 

 biological materials have been extensively treated in various publications.^-^ 

 The method based on the precipitation of choline as the periodide has been 

 one of the preferred chemical procedures. Earliest studies on the precipita- 

 tion of choline periodide were made by Stanek,^ who proposed the use of 

 potassium triiodide as the reagent for the quantitative precipitation of 

 choline. In 1923, Sharpe^ published a quantitative chemical method, based 

 on the original work of Stanek, in which choline was precipitated with 

 iodine as the periodide which was washed free of excess reagent with ice- 

 cold water and decomposed with dilute nitric acid. The liberated iodine 

 was extracted with chloroform and estimated using a standard solution of 

 sodium thiosulfate. 



Roman'' and Maxim^ investigated the original Stanek method and, as a 



2» D. Ackermann and H. Schutze, Zentr. Physiol. 24, 210 (1910). 

 " A. J. Wood and F. E. Keeping, ./. Baderiol. 47, 309 (1944). 



22 G. N. Cohen, B. Nisman, and M. Raynaud, Com-pt. rend. 225, 647 (1947). 



23 G. Ducet, Com'pt. rend. 227, 871 (1948). 

 2« G. Ducet, Ann. agron. 19, 184 (1949). 



1 C. H. Best and C. C. Lucas, Vitamins and Hormones 1, 1 (1943). 



2 P. Handler, Biol. Symposia 12, 361 (1947). 



3 P. Gyorgy and S. H. Rubin, in Vitamin Methods, Vol. 1, p. 243. Academic Press, 

 New York, 1950. 



* Association of Vitamin Chemists, Inc., Methods of Vitamin Assay, 2nd ed., p. 



287. Interscience Publishers, New York, 1951. 

 5 V. Stanek, Hoppe-Seyler's Z. physiol. Chem. 46, 280 (1905); 47, 83 (1906); 48, 334 



(1906). 

 « J. S. Sharpe, Biochem. J. 17, 41 (1923). 



7 W. Roman, Biochem. Z. 219, 218 (1930). 



8 M. Maxim, Biochem. Z. 239, 138 (1931). 



