Raman spectra of 35 lipids are presented and analyzed in this work. Selected compounds, i.e. saturated/unsaturated fatty acids, triacylglycerols, cholesterol, cholesteryl esters and phospholipids, were chosen to review key lipids involved in cardiovascular disease development. Differences in Raman signatures both between diverse groups of lipids as well as various members of the same family are investigated in detail in order to elucidate marker features enabling detection and discrimination of lipids in complex samples, particularly of biological origin. This work complements our previous review on important biomolecules, i.e. proteins, and presents a comprehensive database of Raman spectra of naturally occurring lipids. Copyright © 2014 John Wiley & Sons, Ltd.

Raman spectroscopy of lipids: a review

Separations of lipids by silver ion chromatography.

Occurrence and Characteristics of Oils and Fats

The fatty acid chain elongation system of mammalian endoplasmic reticulum

Determination of double-bond positions in methylene-interrupted dienoic fatty acids by GC-MS as their dimethyl disulfide adducts

A combination of gas-liquid chromatography (GLC) and oxidative cleavage on fractions isolated by mercury derivative chromatography has shown the presence of previously unreported minor component fatty acids in olive, soybean, cottonseed, corn, peanut, rapeseed and safflower oil. All of the oils examined contain small amt of saturated acids above arachidic, some as high as hexacosanoic acid.Cis-11-octadecenoic acid was found in amt ranging from 0.5~2.0%.Cis-11-eicosenoic acid is present in the 0.04~1.4% range (rapeseed oil excluded). The tetracosenoic acid present in rapeseed (0.4%) and safflower oil (0.1%) has been identified as thecis-15-tetracosenoic acid. No unusual polyenoic species were detected with the exception of those in rapeseed oil, which contains 0.6% of both 11,14-eicosadienoic and 13,16-docosadienoic acid.

Minor component fatty acids of common vegetable oils.

A direct gravimetric method has been developed for the determination of saturated fatty acids in fats, oils, and methyl esters. The procedure involves methanolysis of the triglycerides to produce methyl esters, followed by oxidation of the unsaturated methyl esters by potassium permanganate. The undesired, acidic oxidation products are removed by alkaline washing and the saturated methyl esters thus isolated are weighed directly. The method is intended for the determination of saturated fatty acids having C16 or longer carbon chains. Small quantities of C14 saturated acids will be included in the determination if present with other higher saturated acids. The method is applicable to both natural and hydrogenated vegetable oils. It is not applicable to oils containing large amounts of C14 and lower saturated acids. Concentrations of saturated acids ranging from 3 to 90% in known glyceride mixtures and from 0.3 to 95% in mixtures of methyl esters were determined with an average difference from the calculated value of 0.8%. Replicate determinations on samples in the 10 to 30% saturates range gave a standard deviation of 0.3 to 0.4%.

Direct determination of saturated fatty acids in fats, oils, and methyl esters

A comparison of the levels of unsaturation in α-olefin sulfonates (AOS) and related derivatives determined by iodination, bromination and hydrogenation techniques showed that quantitative hydrogenation is the only method having wide applicatbility. Although halogenation methods frequently give results in agreement with hydrogenation data, they can show variations with reaction time and composition of the sample. Unsaturation in sulfonate methyl esters could not be determined by halogenation. The amount of †1-isomer in alkene sulfonate sodium salts determined by oxidative cleavage with periodate-permanganate was always low compared to that determined by NMR. Oxidative cleavage of the sulfonate methyl esters gave †1-isomer levels in agreement with NMR results.

D. F. Kuemmel

Papers

Minor component fatty acids of common vegetable oils.

Direct determination of saturated fatty acids in fats, oils, and methyl esters

Level and position of unsaturation in alpha olefin sulfonates

On the first double bond site in natural fats and oils