BRIEFS E n z y m a t i c D e t e r m i n a t i o n o f P o l y u n s a t u r a t e d Fa t ty A c i d s

A rapid enzymatic method is developed for determining polyunsaturated fatty acids using lipoxidase. The enzyme produces the conjugated diene hydroperoxide which is measured at 234 πΐμ. Direct measurements are made in fats, oils, fatty acids, blood plasma, microorgan­isms, and plant seed with good sensitivity and accuracy.

JOSEPH MacGEE, The Procter and Gamble Co., Cincinnati, Ohio

Anal. Chem. 31,298 (1959)

Spot Tests fo r A r o m a t i c C o m p o u n d s U s i n g 2 , 4 , 7 -Tr in i t ro f tuorenone

A qualitative spot test for aromatic compounds is devised by spraying spots on filter paper with 2,4,7-trinitro-fluorenone. Color and fluorescence vary with the type of aromatic compound reacting. Certain complexes are extractable in iso-octane and ethyl alcohol.

H. T. GORDON and M. J. HURAUX, University of California, Berkeley, Calif.

Anal. Chem. 31,302 (1959)

A n a l y s i s o f L o n g - C h a i n Fat ty A c i d s b y G a s - L i q u i d C h r o m a t o g r a p h y . M i c r o m e t h o d for P r e p a r a t i o n o f M e t h y l Esters

A technique is devised for the quantitative formation of methyl esters of long-chain fatty acids. The esters, sep­arated in pure form by sublimation, ate ready for gas-liquid chromatographic studies. The technique elimi­nates saponification with its several disadvantages.

WILHELM STOFFEL, FLORENCE CHU, and E. H. AHRENS, Jr., Rocke­feller Institute, New York 2 1 , Ν. Υ.

Anal. Chem. 3 1 , 307 (1959)

D e t e r m i n a t i o n o f Q u i n q u e v a l e n t , T r i v a l e n t , a n d O r g a n i c Phosphorus in the A t m o s p h e r e a n d in A q u e o u s Solut ions

A method for determining quinquevalent, trivalent, and organic phosphorous in mixtures is based on the oxida­tion of organic phosphorous with alkaline ammonium persulfate. Calculations are made by differences. Ap­plication is made to atmospheric and aqueous phos­phorous content.

ROY MAY, Tennessee Valley Authority, Wilson Dam, Ala.

Anal. Chem. 3 1 , 308 (1959)

M i c r o d e t e r m i n a t i o n o f A c e t o n e in B io log ica l Fluids

A micromethod for determining acetone is based on the diffusion of the acetone on a filter paper strip into 2,4-dinitrophenylhydrazine solution. The color produced after the addition of sodium hydroxide is read in a photo­electric colorimeter. Interference due to acetaldehyde can be calculated. Method is applicable to biological materials.

M. U. TSAO, G. H. LOWREY, and E. J. GRAHAM, University of Michigan Medical School, Ann Arbor, Mich.

Anal. Chem. 3 1 , 311 (1959)

NaCI KBr CsBr Csl

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VOL. 3 1 , NO. 2, FEBRUARY 1959 · 1 7 A