The dichromate-H2S04 reagent used earli- 

 er by Fillerup and Mead (Proceedings of 

 the Society for Experimental Biology and 

 Medicine , 83: 574, 1953) gave yellow -or- 

 ange background color, and did not permit 

 differentiation between cholesterol- and 

 non-cholesterol -containing lipids. 



Dieckert, J. W. and R. Reiser 



1956. Paper chromatography of phospho- 

 lipides on silicic acid impregnated 

 -^ glass fiber filter paper. Journal of the 



A American Oil Chemists Society , 33 : 



535-537. 

 Phospholipids were separated from their 

 mixtures by chromatography on glass paper 

 impregnated with silicic acid using 1:1 

 methanol -ethyl ether as solvent. 



Dijkstra, G., J. G. Keppler, and J. A. Schols 



1955. Gas-liquid partition chromatogra- 

 phy. Recueil des travaux chimiques 



•^ des Pays-Bas et de la Belgique , 73: 



805-812. Chemical Abstracts, 50: 



1528f (1956). 

 A silicone grease- or paraffin -coated 

 column of celite was used to separate mix- 

 tures of medium chain fatty acids, alcohols, 

 and aldehydes . Other gas chromatographic 

 systems for identification and determina- 

 tion of aliphatic materials are described. 



Dittmer, J. C, J. L. Feminella, and 

 D. J. Hanahan 



1958. A study of the quantitative estima- 

 tion of ethanolamine and serine in the 

 ▲ phospholipids. Journal of Biological 



Chemistry, 233: 862-867. 

 The phospholipids are hydrolyzed with 

 6 2^ HCl, and the free amines are separated 

 by ion exchange . Ethanolamine and serine 

 are estimated as NH released by periodate 

 oxidatio"n of the amines. 



Dole, V. P. 



1956. A relation between non-esterified 

 fatty acids in plasma and the metabolism 



of glucose . Journal of Clinical Investi- 



gation, 35: 150-154. 

 Non-esterified fatty acids are extracted 

 with i so -propyl alcohol-heptane-1 N H2SO4 

 and titrated with 0.018 N NaOH. The meth- 



od measures fatty acids in 1 cc. of plasma 

 to + 3% in replicate analyses. 



Drekter, I. J., A. Bernhard, and J. S. Leopold 



1935. The extraction of cholesterol from 

 blood serum . Journal of Biological 

 Chemistry , 110 : 541-549. 



It was found that alcohol extracts all of 

 the cholesterol from blood serum, while 

 ether only extracts a small part of it. Part 

 of the cholesterol is presumably bound to 

 protein which is denatured by the alcohol, 

 thus allowing complete extraction with alco- 

 hol. 



Drekter, I. J., A. E. Sobel, and S . Natelson 



1936. Fractionation of cholesterol in 

 blood by precipitation as pyridine cho- 

 lesteryl sulfate and cholesterol digiton- 

 ide . Journal of Biological Chemistry , 

 115 : 391-399. 



It was found that the pyridine sulfate meth- 

 od (Sobel, Journal of Biological Chemistry , 

 115: 381, 1936) gave free cholesterol values 

 from 6 to 10% of the total, while for the cho- 

 lesterol digitonide method the value was 25 

 to 35%. The theory is advanced that the dig- 

 itonin method may give higher values due 

 to splitting of loosely bound cholesterol or 

 the precipitation of some form of combined 

 cholesterol other than fatty acid esters . 



Ducet, G. andE. Kahane 



1946. Biochemistry of choline and its 

 derivatives. XX. Identification and 

 chemical determination of choline in 

 biological substances. Bulletin de la 



Societg de chimie biologlque, 28 : 794- 

 805. Chemical Abstracts, 41^ 4188b 

 (1947). 

 After decomposition of the tissue with HNO3, 

 choline is freed by hydrolysis and precip- 

 itated by I„KI or phosphotungstic acid and 

 determined in the precipitate . 



Ducet, G. 



1948. Separation and determination of 

 the water-soluble forms, of choline. 

 Analytica Chimica Acta , 2: 839-843. 



(in French). Chemical Abstracts, 43: 

 7998b (1949). ~~ 



Free choline is adsorbed on silica gel, 



17 



