Isolation Of Free Fatty Acids Research Articles

Analysis of tissue free fatty acids isolated by aminopropyl bonded-phase columns

Gas chromatographic analysis revealed that polyunsaturated fatty acids such as arachidonic acid and total tissue free fatty acids isolated from an aminopropyl bonded-phase column yield a two- to three-fold higher recovery of arachidonic acid as compared to those isolated from thin-layer chromatographic plates. This method was further improved by packing the aminopropyl bonded phase in glass columns, since the glass column significantly eliminated the other contaminants (from polypropylene columns) coeluting with fatty acids in both a neutral lipid thin-layer chromatographic system and on a 5% DEGS-PS column of gas chromatographic analysis. In aminopropyl bonded-phase columns, the standard triglycerides and phospholipids were completely separated from free fatty acids as judged by gas chromatographic analysis. These results warrant the use of an aminopropyl bonded-phase column for the isolation of free fatty acids to obtain better recovery of polyunsaturated fatty acids.

A sensitive method for the determination of free fatty acids in plasma.

A sensitive micromethod for the colorimetric determination of free fatty acids (FFA) in plasma has been developed. FFA are extracted with chloroform-heptane-methanol with silicic acid being added to eliminate interfering phospholipids. Diphenylcarbazide containing diphenylcarbazone has been chosen as color-developing reagent, since the chromophore formed in the presence of FFA-Cu complex is stable and sensitive. Comparison of the proposed method and a non-routine reference procedure involving, among other steps, isolation of FFA on thin-layer chromatography would indicate that the efficiency of extraction of FFA in the proposed method was 90% that of the reference procedure. The proposed method offers the sensitivity, convenience, and accuracy needed for the determination of FFA in situations where the size of sample available is limiting, as with small rodents.

Development and characterization of an improved silicic acid‐KOH arrestant column for routine quantitative isolation of free fatty acids

AbstractAn improved silicic acid‐KOH arrestant column method for the quantitative isolation of free fatty acids (FFA) is described. The method involves preparation of samples in acidified silicic acid caps that are placed directly above alkaline arrestant column portions in glass Chromatographic tubes. Neutral lipids are eluted with solvents whereas FFA are stopped as K‐salts. FFA are recovered by elution with formic acid‐containing solvents. The accuracy and reproduci‐bility of existing methods were greatly improved by minimizing and stabilizing the extent of alkali‐induced glyceride hydrolysis. The improved method is suitable for adaptation to a wide variety of food products and biological systems.

Gas chromatographic identification of free fatty acids in trace amounts in natural materials

A method is proposed for the analysis of small amounts of complicated natural mixtures of fatty acids that are not chemically bonded in lipids. The analysis includes isolation of free fatty acids, formation of methyl esters, preparative gas chromatographic separation, hydrogenation of double bonds and analysis with a system of specially chosen columns. The method was used successfully in the analysis of free fatty acids in salmon flesh in which 52 components were found and 43 were identified, consisting of odd- and even-carbon-numbered acids with 12–24 carbon atoms, 0–6 double bonds and also branched chains.

Gradient-thickness thin-layer chromatography for the isolation and analysis of trace amounts of free fatty acids in large lipid samples

A thin-layer chromatographic method for quantitative isolation of free fatty acids is described. This method appears to be more satisfactory than existing methods in offering the combination of advantages of specificity, simplicity, rapidity, reproducibility, accuracy, high sensitivity, and applicability as a preparative technique. The method involves chromatography on a thin-layer plate on which the layer of Silica Gel G decreases linearly in thickness from 1000 micro at the base to 125 micro at the upper end. This gradient-thickness design allows the separation and densitometric quantitation of very small traces of free fatty acids from relatively large and complex lipid samples in a single chromatographic step. The method has been shown to be applicable directly to the crude total lipid extracts of several mammalian tissues. It appears to generate little if any artifactual free fatty acids from the breakdown of complex lipids, in contrast to the undesirable behavior of silicic acid columns in this respect. Gradient-thickness thin-layer chromatography promises to be useful for the quantitative isolation of trace amounts not only of other types of lipids but also of classes of compounds other than lipids.