Influence of alkali concentration and other factors on the conjugation of natural polyunsaturated acids as determined by ultraviolet absorption measurements

Self Cite

Summary There are several spectrophotometric methods available which allow a high degree of accuracy in the analysis of the common fats and oils. Further there are methods available for those fats and oils that contain unsaturated acids up to and including hexaenoic acid which allow good estimations of the composition. Several sources of error are discussed in an effort to point the way to their elimination. Recently published spectrophotometric data on certain polyunsaturated acids isolated from marine oils are discussed in relation to the possibility of extending the method to include these oils. More accurate spectrophotometric constants to be employed in the analysis of certain drying oils are suggested.

Section: Methods B---11% Koh-glycerol Reagent a Methodsmentioning

confidence: 74%

Section: Methods B---11% Koh-glycerol Reagent a Methodsmentioning

confidence: 99%

Application of ultraviolet spectrophotometry to the analysis of fats and derivatives

Herb

1955

Self Cite

“…Conjugation of the double bonds and examination of the ultraviolet spectrum of the conjugated isomers has been recommended as a method of determining individual constituents in mixtures of unsaturated fatty acids. A method frequently used for the more highly unsaturated fatty acids is that of Herb and Riemensehneider (5). It consists of heating the sample for 15 min.…”

Section: Resultsmentioning

confidence: 99%

“…One of the reasons that many feed users have held back on the use of fats in feed is the fact that most animals as well as poultry will not eat feed containing fats when they have become rancid except to prevent starvation. In addition to this, Quackenbush (5) of Purdue University has reported that fats which are oxidized will bring about a more rapid breakdown of the fat-soluble dietary essentials such as vitamin A, vitamin D, and vitamin K. He also reports that cases of dermatitis and failure of the reproductive organs have been reportedly caused by rancid dietary fat.…”

Section: Apolismentioning

confidence: 99%

Unsaturated fatty acids. I. Low temperature urea complexes of polyunsaturated acids from bovine tissue

McElroy

Jordan

McLaughlin

et al. 1955

Summary A mixture of fatty acids obtained from autolyzed saline extracts of beef testicular tissue was fractionated by crystallization of the urea complexes at 5°, −20°, and −75°C. Fractions rich in docosahexaenoic and in arachidonic acids were obtained as solid complexes. The filtrate remaining after precipitation of the solid urea complexes contained a high percentage of hexaenoic acid of shorter chain length than docosahexaenoic, probably eicosahexaenoic acid.

“…This device ( Figure 2) permitted the removal of a drop of distillate at any time without interruption of the distillation. Each of the chain-length fractions obtained from the distillation of P1, P2, P3, and F was analyzed by gas-liquid chromatography, paper chromatography (15), or alkali-isomerization (8), or a combination of all three methods, depending on their complexity. From these analyses the composition of P1, P.,, P3, and F was determined (Table II) as well as the composition of the original acids.…”

Section: General Proceduresmentioning

confidence: 99%

Preparation and properties of methyl arachidonate from pork liver

Privett

Weber

Nickell

1959

Summary A procedure is described whereby the mixed fatty acids of pork liver lipid are fractionated into groups of acids to facilitate their analysis and isolation. The major acids of pork liver lipid were palmitic 22.9%, stearic 16.8%, oleic 38.5%, linoleic 5.0%, and arachidonic 4.4%. A number of other unsaturated fatty acids were detected in minor amounts, such as isomers of arachidonic, linoleic, and palmitoleic acids. A number of fatty acids of odd‐numbered chain length also were detected. The isolation of methyl arachidonate in a number of preparations of purity ranging from 87 to more than 99% is described. Yields ranged from 44% for the purest arachidonate to 93% for the less pure concentrates. Alkali‐isomerization analyses of methyl arachidonate from this source, by the 21% KOH‐glycol method, gave appreciably different absorptivities from those previously published. Various criteria for estimating purity of polyun‐saturated fatty acids are discussed in the light of results of the analysis of methyl arachidonate.