Thin-layer chromatography of aliphatic γ — and δ -lactones

Homologous aliphatic γ- or δ-lactones are separated by thin-layer chromatography on a mixture of kieselguhr G and silica gel G (1:8). The thin-layer plates are chromatographically impregnated with methanol as the stationary phase and developed 3 times with light petroleum (bp 80–100C) saturated with methanol. γ- And δ-lactones can be separated from each other on the same adsorbent with a 1:1 mixture of light petroleum (bp 30–40C) and isopropyl ether. The systems can be combined 2-dimensionally. The lactones are detected by spraying the chromatoplates either with a 2% solution of iodine in methanol or with alkaline hydroxylamine followed by ferric chloride and acetic acid. These methods were used for the tentative identification of δ-C_10–16 lactones in commercial Australian butteroil.     

Chromatographic analysis of polyglycerols and their fatty acid esters

Polyglycerols and their fatty acid esters have been analyzed by gas-liquid chromatography (GLC) as trimethylsilyl ether derivatives. Linear diglycerols and triglycerols were isolated from commercial polyglycerols by vacuum distillation. Mono- and di-fatty acid esters were synthesized in the laboratory. Two isomers of diglycerol have been separated and identified. GLC analysis was carried out on columns packed with 3% JXR on Gas Chrom Q. Response factors for diglycerol and triglycerol relative to glycerol have been established. Commercial polyglycerol esters are shown to be mixtures of glycerol, free fatty acids, mono- and diglycerides, and mono- fatty acid esters of diglycerol and triglycerol. Separation of free polyglycerols and their esters is also demonstrated by thin-layer chromatography on Silica Gel-G containing 4.0% boric acid.     

Metal-requiring and non-metal - requiring catalysts in the autoxidation of methyl linoleate

During the autoxidation of methyl linoleate, peroxide-containing substances are formed which, when added to unoxidized methyl linoleate, will catalyze oxygen uptake. Materials active only in the presence of added metal ions (MCs) were not inactivated during aerobic thin-layer chromatography on silicic acid or alumina but were selectively inactivated by treatment with triphenylphosphine. Catalysts not requiring added metal ions for activity (NCs) are not affected by triphenylphosphine, but the catalytic activity is lost during aerobic thin-layer chromatography. Autoxidized methyl linoleate was separated into four peroxide-containing fractions by elution from a silicic acid column with hexane-diethyl ether mixtures. Each fraction was found to contain both MCs and NCs. Presented at the 4th International Symposium on Metal Catalyzed Lipid Oxidation, London, April 1975.     

Neue Methoden zur quantitativen Analyse von Etherlipiden

Some New Methods for the Quantitative Analysis of Ether Lipids A simple and reliable procedure for the determination of the ratio alkylglycerolipids to l-alkenylglycerolipids is carried out as follows: A “total lipid extract” is reduced with lithiumaluminiumhydride to yield a mixture of alkylglycerols, l-alkenylglycerols, and alcohols. Acetylation of these reduction products with radioactively labelled acetic anhydride leads to a mixture of alkyldiacetylglycerols, l-alkenyldiacetylglycerols, and alkylacetates. This mixture is resolved into the three lipid classes by thin-layer chromatography on silica gel. The ratios of the radioactive derivatives and, thereby, the ratio ether lipids to ester lipids as well as the ratio alkylglycerolipids to l-alkenylglycerolipids are determined by scanning of the thin-layer chromatograms. For the analysis of the alkyl and l-alkenyl moieties the groups of alkyldiacetylglycerols and l-alkenyldiacetylglycerols are separated from the alkylacetates by thin-layer chromatography and treated with hydrochloric acid in diethylether. The resulting mixture of alkyldiacetylglycerols and aldehydes (derived from l-alkenyldiacetylglycerols) is resolved by gas chromatography. The various aldehydes, which are well resolved from each other, are eluted ahead of the alkyldiacetylglycerols, which are also well resolved from each other. The methods described have been applied to the analysis of the lipids of mammalian hearts and of shark liver oils; they proved to yield precise values in a relatively short time. Methods for the synthesis and analysis of ‘PAF’ (‘Platelet Activating Factor’) are reviewed.     

New TLC and OPTLC Methods for the Separation of Serum Lipids

Rapid methods for the separation of major lipid classes varying in polarity from cholesterol esters to lysophosphatidylcholine are presented, which were used for the analysis of extracts obtained from human sera. Solvent systems for lipid separation by overpressured thin-layer chromatography and thin-layer chromatography are described. These techniques are suitable to separate unsaturated and saturated cholesterol esters according to the number of carbon atoms, double bond numbers of their fatty acid contents. Fourteen lipid fractions may be separated using two successive developments in the same direction.     

Desulphurisation and Reduction Studies of Epithio Fatty Acids and Alcohols

The cis and trans epithio fatty acids and alcohols with Raney Ni give the corresponding saturated derivatives. Lithium aluminium hydride reduction of cis epithio fatty acids either in tetrahydrofuran or in ether yields both mercapto alcohol isomers which can be separated and identified by thin-layer chromatography. The trans isomer on similar treatment however furnishes the mercapto alcohols in tetrahydrofuran only, while in ether medium the epithio group remains unaffected. The isomeric mercapto alcohols on desulphurisation likewise afford the saturated alcohols.     

Reaction of lipids containing hydroxy groups with trimethylsulfonium hydroxide: Formation ofO-methyl derivatives

Base-catalyzed transesterification of acyl lipids with trimethylsulfonium hydroxide (TMSH) is an easy and convenient method for the preparation of fatty acid methyl esters (FAME) for gas chromatography (GC) analyses. We have found, however, that lipids containing hydroxy groups are partially converted to the correspondingO-methyl ether derivatives which may interfere with FAME in GC separations. For example, long-chain alcohols are found to be converted to alkyl methyl ethers,rac-1-O-alkylglycerols to the corresponding 2-O-and 3-O-monomethyl ethers, as well as 2,3-di-O-methyl ethers, hydroxy fatty acids to methoxy FAME, and cholesterol to cholesteryl 3β-methyl ether. From our results, it is obvious that TMSH derivatization method is not recommended without limitation for lipids containing hydroxy groups; it may be, however, of some diagnostic value for the analysis of such lipids by GC/mass spectrometry.     

Structure of bovine milk fat triglycerides

The triglycerides of bovine milk fat globules were isolated and separated into short, medium and long chain lengths by thin-layer chromatography. The molecular weight distribution and the fatty acid composition of the component triglycerides was then separately determined by gas chromatography following argentation-thin-layer and preparative gas chromatography. Some 38 triglyceride types (28% of total), of which there could be up to 6 isomers, were specifically identified and quantitatively estimated. The quantitative estimates for the rest of the milk fat triglycerides were limited to much more complex glyceride groups. The results confirm the earlier claim that butyric and caproic acids occur in milk fat almost exclusively in combination with medium and long chain fatty acids. Presented in part at the AOCS Meeting, Philadelphia, October, 1966.     

Synthesis and properties of novel fluoroalkyl end‐capped oligomers containing phosphorus segments

New fluoroalkyl end‐capped oligomers containing pendant phosphoric acid groups wereprepared by the reactions of the corresponding monomer with fluoroalkanoyl peroxides. It was demonstrated that not only strong aggregations of fluoroalkyl segments but also hydrogen bonding could interact synergistically to form the highly viscoelastic fluids (gel‐like fluids) in aqueous solutions of these new fluoroalkyl end‐capped oligomers containing pendant phosphoric acid groups. Furthermore, these oligomers were able to reduce the surface tension of water effectively to exhibit a clear breakpoint resembling a CMC, and the modified stainless‐steel surface treated with these oligomers was shown to possess an excellent property imparted by fluorine. More interestingly, these oligomers were found to be potent and selective inhibitors against HIV‐1 replication in vitro. New fluoroalkyl end‐capped phosphonic acid and phosphonate oligomers were also prepared by the reactions of the corresponding phosphonic acid and phosphonate monomers, respectively, by the use of fluoroalkanoyl peroxides. These new fluoroalkyl end‐capped phosphonic acid and phosphonate oligomers were found to have a higher solubility in not only water but also in common organic solvents than that of the corresponding fluorinated oligomers containing pendant phosphoric acid groups, and these new oligomers were able to reduce the surface tension of these solvents quite effectively. Thus, these oligomers are expected to develop as new fluorinated oligosurfactants. Moreover, the modified poly(methyl methacrylate) surface treated with these phosphonate oligomers was clarified to exhibit a good oil‐repellency imparted by fluorine. In addition, fluoroalkyl end‐capped phosphonate homo‐ and cooligomers were found to form monomolecular films at the air–water interface. Therefore, these fluorinated oligomers are suggested to have high potential for new functional materials through not only their excellent properties imparted by both fluorine and phosphorus, but also through their biological properties. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 79: 228–245, 2001     

Isolation and characterization of glycerides in human hair lipids by thin-layer and gas chromatography

Techniques for the quantitative analysis of hair lipids using thin-layer chromatography (TLC) together with a proximate analysis of components in one sample deduced by these criteria are presented. Mono-, di- and triglycerides were separated by TLC using Silica Gel G as adsorbent. The chromatoplates were developed with 98% acetone+2% petroleum ether. Glycerides moved with the solvent front. The requisite portions were scraped off the plates and extracted with acetone and ether. Further TLC, limiting the migration of triglycerides and diglycerides was afforded by use of 95% ethanol as solvent in one direction while monoglycerides moved with the solvent front. For the separation of monoglycerides, chloroform was used as solvent in a second direction. Reference standards and several mixtures were run simultaneously and the spots identified by charring with concentrated sulfuric acid containing dichromate. Additional checking was effected by IR spectra. For determination of glyceride composition, methyl esters of the component fatty acids were prepared by transesterification and submitted to gas chromatography. Comparison of the levels of each of the constituent fatty acids showed no remarkable differences between the three classes of glycerides in one hair lipid pool. Although certain discrepancies in the amounts of a few fatty acid components might be construed for one pool of lipids from hair of white full-headed men (WF-9A) in contrast to findings with two Negro pools, no unequivocal conclusions can be drawn presently.     

Rapid analysis of fatty acids in plasma lipids

A rapid and convenient procedure for the quantitative determination of the fatty acid composition of plasma lipids is described. Human plasma was applied directly to the preadsorbent zones of thin-layer silica gel plates with added antioxidant, internal standards and carriers. The thin-layer chromatography (TLC) plates were partially developed with methanol followed by chloroform/methanol (1∶1, v/v), and then they were fully developed in hexane/diethyl ether/acetic acid (80∶20∶1, v/v/v) to separate the major classes of lipids. Silica gel from regions containing the separated lipids was scraped into screw-capped tubes and treated with boron trifluoride-methanol prior to gas chromatography. The method of direct application to TLC plates gave yields and compositions of fatty acids very similar to the method of applying extracted plasma lipids. This relatively simple method is suitable for analyzing the fatty acids in plasma lipids from a 50 microliter finger-tip blood samples from an individual, and it may be useful in wide-scale screening of different individuals to estimate the relative amounts of ingested polyunsaturated fatty acids. Pfizer Biomedical Research Awardee.     

Estimation of polyunsaturated fatty acid content in lipids of aquatic organisms using thin-layer chromatography on a plain silica gel plate

We have designed a rapid method for the separation of polyunsaturated fatty acids (PUFA, ≥trienes) from non-PUFA, and for estimation of total amounts of PUFA in lipids of aquatic organisms. Lipids from thirty-one species, including marine and fresh water fishes, shell fishes, marine algae, and other aquatic animals, and from terrestrial organisms, were transesterified with sodium methoxide in methanol. The resulting fatty acid methyl esters were separated by thin-layer chromatography on commercially available plain silica gel plates with a developing solvent ofn-hexane/ethyl ether/acetic acid (95∶5∶1, by vol). All of the methyl esters from aquatic organisms tested separated into two spots, whereas those from terrestrial sources, except for linseed oil, showed a single unresolved spot. The upper and lower spots were scraped separately from the plate, and their fatty acid compositions were determined by gas-liquid chromatography. The lower spot was composed of PUFA having more than two double bonds, whereas components of the upper spot were saturated, monoenoic, and the greater part of the dienoic fatty acids. When the spots on the silica gel plate were stained with Coomassie brilliant blue, the amounts of PUFA in aquatic organisms could be estimated satisfactorily using a scanning densitometer. Presented in Japanese at the general Meeting of JSSF held in Mie University, Tsu-city, Japan, October 1994.     

Separation and identification of triximenynin from Santalum spicatum R. Br.

Seed lipids of Western Australian sandalwood (Santalum spicatum) were separated using preparative thin-layer chromatography. The oil contains about 49% oleic acid and about 40% ximenynic acid. The individual triacylglycerol bands were characterized by high-performance liquid chromatography and gas chromatography. The oil consisted of three major triglycerides: triximenynoyl-glycerol (triximenynin), an oleoyl-diximenynoyl-glycerol, and a dioleoylximenynoyl-glycerol, as demonstrated by gas chromatography with mass selective detection.     

Quantitative Bestimmung der apolaren dimeren Fettsäuren in Fetten und Ölen

Quantitative Determination of Unpolar Dimeric Fatty Acids in Fats and Oils Fatty acids obtained by saponification of fats followed by removal of unsaponifiables and petroleum ether insoluble oxidized fatty acids, were treated to give urea-adducts. The mixture of fatty acids which did not form adducts was esterified and separated by thin-layer chromatography. It was shown by mass-spectrometry that the methyl esters of unpolar dimeric fatty acids occupied a definite zone in the chromatogram. The methyl esters of unpolar dimeric fatty acids can be quantitatively estimated by charring the chromatogram under standardized conditions and densitometry of the above zone, whereby a test substance is co-chromatographed for comparison. The relative standard deviation in the chromatography and densitometric determination was approximately 10%. The lower limit of detection was at 0.005% of the methyl ester of unpolar dimeric fatty acid. Using dimeric fatty acids lebelled with radioactive carbon, it was proved that approximately up to 90% of the unpolar dimeric fatty acids can be detected by this method.     

Autoxidative dimerization of methyl linolenate and its monohydroperoxides,hydroperoxy epidioxides and dihydroperoxides

The structures of dimers and oligomers produced by autoxidation of methyl linolenate and its purified oxidation products were investigated to obtain a better understanding of the mechanism of oxidative deterioration of unsaturated lipids. The dimers were separated by gel permeation chromatography, characterized by molecular weight determinations before and after sodium borohydride reduction, and analyzed by ultraviolet, infrared,¹H NMR and fast atom bombardment mass spectrometry. Autoxidation of methyl linolenate at 40 C to peroxide value of 1062 produced 6.8% dimers mainly derived from hydroperoxides, hydroperoxy epidioxides and dihydroperoxides. These dimers were 88% peroxide-linked (C-O-O-C) and 12% ether- (C-O-C) and/or carbon-linked (C-C). Autoxidation of methyl linolenate monohydroperoxides at 40 C produced dimers that were 72% peroxide- and 28% ether/carbon-linked. Thermal decomposition of linolenate hydroperoxides at 150 C gave dimers that were 100% ether/carbon-linked, and catalytic decomposition with ferric chloride-ascorbic acid at room temperature gave dimers with 43% peroxide and 57% ether/carbon linkages. Autoxidation of linolenate hydroperoxy epidioxides at 40 C produced dimers containing hydroperoxy epidioxides, dihydroperoxides and monohydroperoxides joined with peroxide and ether/carbon linkages. Under the same conditions, autoxidation of linolenate dihydroperoxides produced dimers containing dihydroperoxides and hydroperoxy epidioxides joined with peroxide and ether/carbon linkages. These dimers contribute to oxidative and flavor deterioration of polyunsaturated fats in the same way as the hydroperoxide precursors by further decomposition to produce volatile compounds. Visiting scientist from Tohoku University, Sendai, Japan.     

Gas chromatographic analysis of ester-type surfactants by using mixed anhydride reagent

Polyoxyethylene alkyl ether sulfates, polyoxyethylene alkyl ether phosphates, and polyoxyethylene fatty acid ester-type surfactants have been analyzed by gas chromatography after chemical decomposition by using the mixed anhydride of acetic and p-toluene-sulfonic acids. In this way, the hydrophobic groups of the polyoxyethylene alkyl ether sulfates and polyoxyethylene alkyl ether phosphates can be identified in the form of alkyl acetates, and the alkyl compositions can be determined easily. On the other hand, the hydrophobic groups of the polyoxyethylene fatty acid ester-type surfactants, such as polyoxyethylene fatty acid ester, polyoxyethylene glycerol fatty acid ester, and polyoxyethylene sorbitan fatty acid ester, have been identified after conversion into their corresponding fatty acids. At the same time, the base compounds of the hydrophilic groups have been converted into ethylene glycol diacetate, glycerol triacetate, and isosorbide diacetate, respectively, so these surfactants may be distinguished easily.     

Lipids in sea water

Acidified and filtered sea water samples which were extracted with petroleum ether and ethyl acetate have been shown to contain a variety of lipid compounds in trace amounts. Concentrations of these solvent-soluble substances ranged from 0.5 to 6.0 mg/liter, the lower concentrations being found in offshore waters. The solvent extracts of the sea water were separated into eight lipid classes by column chromatography on silicic acid. The fractions eluted with solvents of increasing polarity were characterized by thin-layer chromatography, infrared and ultraviolet absorption and gas chromatography. These techniques revealed a complex mixture of alkanes, alkenes, fatty acids, steroids, phospholipids and many as yet unidentified components. Twenty to thirty alkanes were present as indicated by gas chromatography. No aromatic hydrocarbons were detected. Chromatography of the methyl esters of the fatty acids indicated the presence of acids with chain lengths varying from 14 to 22 carbons, both saturated and unsaturated. In many samples the unsaturated fatty acids containing 18 to 22 carbons predominated. The lipid components varied somewhat in composition as well as concentration from location to location and with season and depth.     

The triglycerides of sable fish (anaplopoma fimbria). II. fatty acid distribution in triglyceride fractions as determined with pancreatic lipase

Sable fish muscle lipids were fractionated on a silicic acid column with mixtures of chloroform and methanol as eluting solvents. Three main peaks containing only triglycerides were isolated; 11 additional peaks contained phosphorous. Each of the 3 triglyceride peaks was separately fractionated into 300 fractions on silica gel columns impregnated with silver nitrate. Mixtures of petroleum ether and ethyl ether were the eluting solvents. About 25 distinct fractions were isolated from each column. The fractions were characterized for fatty acid content by gas chromatography of the methyl esters. The results showed that the fractionation did not depend upon the presence of single fatty acids but upon total unsaturation. Fatty acid distribution within each fraction was determined with the use of hog pancreatic lipase, followed by thin-layer chromatography and gas chromatography. Presented at the AOCS Meeting in Houston, Texas, 1965.     

脂肪酸甘油酯的色谱分析

应用高效液相色谱法和高分辨凝胶渗透色谱法建立了脂肪酸甘油酯中单酯、双酯和三酯的族分离方法 ,采用乙醇作流动相的非水反相色谱法可以将饱和脂肪酸甘油酯按族进行分离 ,不饱和脂肪酸甘油酯在反相色谱条件下族分离效果不理想 ;相比于HPLC方法 ,采用四氢呋喃作流动相的GPC法可以迅速地将各种多元醇酯按族进行分离 ,而且具有快速、简便等特点     

Separation of lipids containing phytanic acid by thin-layer chromatography

Cholesteryl phytanate and triglycerides containing phytanic acid were separated from their normal fatty acid analogs by thin-layer chromatography. The presence of the branched-chain fatty acid makes the lipid less polar, and this effect becomes more pronounced as the number of phytanic acid residues in the triglycerides is increased. Phytanic acid was prepared from commercial phytol by catalytic hydrogenation, followed by catalytic oxidation. It contained 5% pristanic acid.