Wheeldon, L. W. and F. D. Collins 



1957. Studies on phospholipids. I. The 

 determination of amino nitrogen in un- 



A hydrolyzed phospholipids . Bipchem- 



ical Journal, 66: 435-441. 

 I-flouro-2:4-dinitrobenzene is reacted 

 directly with the NH2 groups of the unhy- 

 drolyzed phospholipid in the presence of 

 triethylamine, and the colored compounds 

 formed are estimated colorimetrically. 



Wheeldon, L. W. and F. D. Collins 



1958. Studies on phospholipids. 3. De- 

 termination of choline . Biochemical 



^ Journal , 70: 43-45. 



The lipid sample is hydrolyzed at 100° in 

 ethanol-HCl. Choline is precipitated as 

 choline phosphomolybdate, washed with iso- 

 butanol, and dissolved in acetone. H2SO4 

 and SnCl2 are added and the optical density 

 of the blue solution is measured at 630 m;,;. 

 The method agrees closely with the reineck- 

 ate method of Click . Added choline was 

 quantitatively recovered. 



White, L. K. 



1946. Spectrophotometric determination 

 of glycerol. Oil and Soap , 23: 323- 

 326. Chemical Abstracts, 41:56d(1947). 

 A procedure for determination of glycerol 

 by spectrophotometric measurement of the 

 blue color of the copper -glycerol complex 

 is described. 



White, M . F . and J . B . Brown 



1949. A study of the tetrabromide meth- 

 od of estimating linoleic acid in fatty 

 # acid mixtures. Journal of the American 



Oil Chemists Society, 26: 385-388. 

 The yield of insoluble tetrabromides from 

 bromination of linoleic acid is affected by 

 the composition of the petroleum ether used 

 as solvent, and by the amounts of linoleic 

 acid and other fatty acids in thg sample 

 used. 



Whitehorn, J. C. 



1924-1925. A method for the determina- 

 tion of lipoid phosphorus in blood and 

 ▲ plasma . Journal of Biological Chemis- 



try, 62: 133-138. 

 The extracted lipids are digested with 



H2SO4-HNO3. Molybdate color is developed 

 with sodium sulfite and hydroquinone . 



Whittaker, V. P. andS. Wijesundera 



1952. The separation of esters of cho- 

 _. line by filter -paper chromatography. 

 ^ Biochemical Journal, 51 : 348-351. 



Choline esters were separated by paper 

 chromatography using n-propanol- or 

 n-butanol -water as solvents. The esters 

 were detected on the chromatogram by us- 

 ing hydroxylamine- ferric chloride, iodine, 

 or phosphotungstic acid-stannous chloride. 



Wiese, H. F. and A. E. Hansen 



1953. Semimicromethod for unsaturated 

 _ fatty acids of blood serum . Journal of 

 * Biological Chemistry, 202 : 417-423. 



The unsaturated fatty acids from 3 ml . of 

 blood serum are isomerized by treatment 

 with 11% KOH in ethylene glycol at 180° for 

 25 minutes, and read spectrophotometri- 

 cally . 



Williams, H. H., B. N. Erickson, I. Avrin, 

 S. S. Bernstein, and I. G. Macy 



1938. Determination of cephalin in phos- 

 pholipids by the estimation of choline. 

 ▲ Journal of Biological Chemistry , 123 : 



111-118. 

 The total phospholipid is determined on an 

 aliquot of tissue extract by Bloor's oxidative 

 titrimetric method (Journal of Biological 

 Chemistry, 82: 273, 1929). Choline is de- 

 termined as the reineckate on a second ali- 

 quot after Ba(0H)2 hydrolysis, and cephalin 

 is calculated as the difference in total and 

 choline -containing phospholipid. 



Willis, G. C, Jr. 



1950. Preparation of fatty acid methyl 

 _ esters. Chemi st - Analyst , 39: 62. 



Methyl esters of the fatty acids may be 

 prepared by treating a methanolic solution 

 of the acid with concentrated H2SO4 and 

 heating to remove excess MeOH. The re- 

 action is essentially complete. 



Winzler, R. J. and E. R. Meserve 



1945. Spectrometric determination of 

 small amounts of choline . Journal of 

 Biological Chemistry, 159: 395-397, 

 Choline reineckate in acetone is 



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