Bestimmung von cyclischen Fettsäuren über eine Harnstoffsäule

Determination of Cyclic Fatty Acids on Urea Column Cyclic monomeric fatty acids (CFA) in the mixture of straight chain saturated and unsaturated fatty acids were determined after methylation (CFA-Me) as non-adducts on an urea column. The method gives quantitative results with mixtures containing 5% or more of cyclic fatty acids. The determination is easy and rapid.     

正常小鼠和肿瘤小鼠毛发中长链脂肪酸含量测定及比较

以正十七酸为内标 ,氯化氢 甲醇抽提和酯化 ,对正常、肿瘤、抗肿瘤小鼠毛发中长链脂肪酸——豆蔻酸、棕榈酸、棕榈油酸、油酸、硬脂酸和亚油酸进行毛细管柱气相色谱定量分析和比较。结果显示 :肿瘤小鼠或抗肿瘤小鼠毛发中长链脂肪酸含量明显升高 ,不饱和长链脂肪酸比例升高而饱和长链脂肪酸比例下降 ,提示毛发中不饱和长链脂肪酸尤其亚油酸与生物体内肿瘤的发生和存在有密切关系。本实验方法简单 ,所需样品量少 ,实验重现性好 ,回收率达定量分析要求。     

Synthesis of alkyl‐branched fatty acids

Alkyl‐branched fatty compounds are of interest for industrial products in the cosmetics and lubricant areas. In this review, clay‐ and zeolite‐catalyzed isomerizations of unsaturated fatty compounds, especially of oleic acid, are discussed. While clay‐catalyzed reactions give most complex mixtures of dimeric fatty acids and of monomeric so‐called “isostearic acid”, the zeolite‐catalyzed process yields preferentially an isomeric mixture of isostearic acids having the methyl branch on the 8–14 positions of the alkyl chain. Synthetically useful additions of alkyl radicals can only be performed on ω‐unsaturated fatty compounds, whereas perfluoroalkyl iodides were added to fatty compounds with terminal as well as internal double bonds using electron transfer‐initiated radical addition reactions. Electrophilic additions of alkyl carbenium ions generated by decomposition of alkyl chloroformates by ethylaluminum sesquichloride give well‐defined alkyl‐branched oleochemicals with good yields.     

Heat Treatment and Chemical Composition of Fatty Acids and Rosin Acids Mixtures: Effects on Their Thermal Properties and Morphology

Mixtures of fatty acids and rosin acids are industrially important products utilized as a raw material for several purposes. Their thermal properties, especially cold stability and crystallization behavior is also important. Several fatty acid and rosin acid mixtures both from industrial products and from commercially available fatty and rosin acids were prepared and treated for 30 min at 80 °C under an inert atmosphere. Thereafter, the mixture was cooled to the desired temperature. Determination of the cloud point, chemical analysis of liquid and solid phase, thermal analysis by differential scanning calorimetry as well as morphology analysis by scanning electron microscopy were performed. The results revealed that crystallization was more rapid when it occurred at 10 °C compared to 25 °C. The crystal sizes increased with decreasing the crystallization temperature. Furthermore, crystals were of irregular shape and agglomerated when rapid cooling of the mixture occurred. Chemical analysis revealed that liquid phase was enriched with stearic acid, whereas crystals contained large amounts of abietic, dehydroabietic and linoleic acids. The cloud point of the mixtures increased with increasing amount of stearic and rosin acids. Dehydroabietic acid addition improved the cold stability of the synthetic fatty acid–rosin acids mixture.     

Bestimmung aromatischer Fettsäuren in hydrierten cyclischen Fettsäuren

Determination of Aromatic Fatty Acids in Hydrogenated Cyclic Fatty Acids Small amounts of aromatic fatty acids, besides hydrogenated cyclic fatty acids, in an urea non-adduct from hydrogenated fatty acids can not be determined by gas chromatography. A direct determination by UV-spectroscopy is also inaccurate, since the strong end absorption of the carbonyl group makes an evaluation of the aromatic band in the range of 260 to 275 nm difficult. After reducing the acids or esters with lithium aluminium hydride to the corresponding alcohols, a proper quantitative determination of aromatic fatty acids can be carried out even at low concentrations of the latter.     

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.     

On the Mechanism of the Thermal Polymerization of Linseed Oil

The monomeric and polymeric glycerides present in thermally polymerized linseed oils can be separated quantitatively by molecular distillation. Analysis of the fatty acids of monomeric and polymeric glycerides indicate the occurence of intra- and intermolecular condensations respectively. Whereas in the former reaction, leading to the formation of bicyclic, dimeric fatty acid groups within the orginal glycerides, no increase in the molecular weight of the oil takes place, in the latter one, characterized by an increase in the molecular weight, fatty acids of different glyceride molecules are involved. It is shown, however, that the overall increase in molecular weight is due to the dimeric glycerides which are formed by interesterification reactions between glyceride monomers containing dimeric fatty acid groups, the latter resulting from intramolecular condensation.     

Analyses of lipids and oxidation products by partition chromatography. Fatty acid hydroperoxides

A liquid partition chromatographic method was developed to isolated and determine hydroperoxides in autoxidized fatty acids or their methyl esters. By the use of benzene containing 2 to 4% methanol as the mobile solvent, the hydroperoxides were separated from unoxidized fatty acids or methyl esters and from secondary and polymeric decomposition products. In the analyses of oxidized fatty acids, diethyl ether was necessary to elute the secondary decomposition products. Saponification of autoxidized fatty esters destroyed the peroxides as determined iodometrically, but the resulting acids contained a fraction which was eluted in the same position as hydroperoxide acids. Evidence showed that this fraction is a monomeric hydroxy fatty acid containing conjugated cis-traux and trans-trans unsaturation. Fatty ester hydroperoxides were isolated chromatographically in yields and purity comparable to those reported in the literature by countercurrent distribution. The concentrations of methyl linoleate hydroperoxide determined chromatographically were smaller than indicated by the peroxide value and diene conjugation of the autoxidized methyl linoleate. This is a laboratory of the Northern Utilization Research and Development Division, Agricultural Research Service, U.S. Department of Agriculture.     

Bestimmung des Gehaltes an petroläther-unlöslichen oxidierten Fettsäuren zur Beurteilung von Brat- und Siedefetten

Determination of the Content of Petroleum Ether Insoluble Oxidized Fatty Acids for the Evaluation of Frying Fats Determination of the content of petroleum ether insoluble oxidized fatty acids is important for the evaluation of used frying fats. Presently, the DGF-Standard Method C-III 3 (68) for the determination of “oxidized fatty acids” is used for the examination of such fats. This method has been thoroughly revised by the working group “Analysis and Standard Methods” of the German Society for Fat Science and presented as Method C-III 3 (77) for “Petroleum ether insoluble oxidized fatty acids”, which is shortened by the step involving separation of unsaponifiable matter. Both methods C-III 3 (68) and C-III 3 (77) were evaluated in collaborative ring tests. Statistical evaluation of the results showed the same reproducibility for both methods, whereas the comparability according to the method C-III 3 (77) is much better than that according to the method C-III 3 (68). Therefore, the method C-III 3 (77) should be applied in future.     

Kurzfristige Fütterungsversuche mit Methylestern dimerer Fettsäuren

Short-Time Feeding Tests with Methyl Esters of Dimeric Fatty Acids Fatty acid methyl esters ex safflower oil were polymerised at high temperature and separated by distillation. Feeding experiments with rats at a level of up to 50 cal-% in the food showed the highest degree in growth retardation with those fractions which contained esters of dimeric fatty acids. Esters of dimeric fatty acids of well defined structure, were fed to mice per os to determine acute toxicity. With the compounds applied the toxicity was far higher than 20 ml/kg body weight. After feeding radiocarbon labelled dimeric fatty acid esters, it could be shown that a high percentage of the material fed was excreted. However, a small amount is metabolised since ¹⁴CO₂ was observed in the exhaled air, and radioactive monomeric fatty acids were found in the body fat. Finally a small amount of the labelled dimeric fatty acids fed to the rats was recovered from the body fat indicating direct incorporation.     

Analysis of fats and oils by gas-liquid chromatography and by ultraviolet spectrophotometry

1. Known mixtures of pure fatty acid methyl esters and a number of fats and oils as their methyl esters have been analyzed by conventional GLC with thermal conductivity detectors.
2. Percentage of fatty acid distribution determined by GLC agreed well with known percentages in model mixtures and with analysis by the spectrophotometric method for fats and oils.
3. Determination of very small amounts of arachidonic and pentacnoic acids in lard by GLC was not successful.

     

Nachweis und Bestimmung von cyclischen C18-Fettsäuren in isomerisiertem Leinöl

Detection and Determination of Cyclic C₁₈-Fatty Acids in Isomerised Linseed Oil When linseed oil is isomerised with ethylene glycol and KOH under conditions which are employed for the UV-spectrophotometric determination of linoleic and linolenic acids, isomeric C₁₈-cyclic fatty acids to an extent of 10% of the linseed oil (20% of linolenic acid) are formed besides straight chain conjugated fatty acids. Lesser amount of cyclic acids are formed if the isomerisation is carried out with NaOH-ethylene glycol or K-tert-butylate. Ilinol, a linseed oil obtained by catalytic isomerisation with Ni/S, was found to contain ca. 5% cyclic C₁₈ fatty acids. The cyclic fatty acids are mixtures of many isomers, their composition being dependent on the conditions employed for isomerisation.     

Die Dünnschicht-Chromatographie auf dem Fettgebiet,XIX. Mitteilung: Mikroanalytische Bestimmung von Phospholipoiden und der darin enthaltenen Fettsäuren in biologischem Material

The Thin-layer Chromatography in the Field of Fats XIX: Determination of Phospholipids and the Fatty Acids in the same in Biological Materials Phospholipids from different sources were separated partly by two dimensional thin-layer chromatography and with partially impregnated silver nitrate plates. The fatty acids were determined nearly quantitatively. The alkaline methanolysis to obtain the methyl esters of fatty acids was carried out on the thin-layer plates.     

Isolierung und Strukturaufklärung polyverzweigter Fettsäuren aus Fischöl

Isolation and Structure Determination of the Polybranched Fatty Acids from Fish Oil From a sample of sea fish oil, three saturated polymethyl branched fatty acids could be separated in pure state as methyl esters by using urea adduct, column chromatography and distillation methods. These could be identified as 4,8,12-trimethyl-tridecanoic acid, 2,6,10,14-tetramethyl-pentadecanoic acid and 3,7,11,15-tetramethyl-hexadecanoic acid, with the help of molecular weight determination, ultimate analysis, IR-, NMR- and mass-spectroscopy. The structures could be proved by synthesis. Many other branched chain fatty acids were synthesised for comparison. The synthesis and the infrared spectrums of these compounds are given in details.     

Zur Fleischartbestimmung aus Fettbestandteilen und Fettbegleitstoffen

Determination of the Nature of Meat from the Fat-Components and Substances Accompanying Fats Foodstuffs in a ready-to-serve state are more and more preferred by the consumer. In order to prevent adulteration as far as possible, investigations within the scope of general control must include the examination of the nature of meat as well. Taking the examples of beef, pork and meats of horse, cangaroo, hare, tiger and elefant, it is shown, that on the basis of polyunsaturated fatty acids (linoleic, linolenic, and arachidonic) along with cholesterol of the meat fat, a reasonably good assessment of the nature of the meat can be performed.     

Analysis of hydroxylated fatty acids from plant oils

A novel process has been described recently for the preparation of hydroxylated fatty acids (HOFA) and HOFA methyl esters from plant oils. HOFA methyl esters prepared from conventional and alternative plant oils were characterized by various chromatographic methods (thin-layer chromatography, high-performance liquid chromatography, and gas chromatography) and gas chromatography-mass spectrometry as well as¹H and¹³C nuclear magnetic resonance spectroscopy. HOFA methyl esters obtained fromEuphorbia lathyris seed oil, low-erucic acid rapeseed oil, and sunflower oil contain as major constituents methylthreo-9,10-dihydroxy octadecanoate (derived from oleic acid) and methyl dihydroxy tetrahydrofuran octadecanoates, e.g., methyl 9,12-dihydroxy-10,13-epoxy octadecanoates and methyl 10,13-dihydroxy-9,12-epoxy octadecanoates (derived from linoleic acid). Other constituents detected in the products include methyl esters of saturated fatty acids (not epoxidized/derivatized) and traces of methyl esters of epoxy fatty acids (not hydrolyzed). The products that contain high levels of monomeric HOFA may find wide application in a variety of technical products.     

Rapid determination of free fatty acids in vegetable oils by gas liquid chromatography

Determination of the free fatty acids in small quantities of vegetable oil is accomplished by gas liquid chromatography. The free fatty acids are isolated from a hexane solution of the vegetable oil into an aqueous solution of trimethylphenylammonium hydroxide (TMPH). Due to the alkalinity of TMPH, the free fatty acids readily partition into this aqueous phase. Injection of the free fatty acid-TMPH salts into a gas chromatograph results in pyrolytic methylation of the free fatty acid salts—yielding the methyl esters. Excellent results were obtained when this new procedure was used on neutral lipid oils containing known amounts of free fatty acids and compared with the results obtained by a modified BF₃/MeOH esterification procedure. When compared to the AOCS titration procedure, this new procedure gave comparable results. This new procedure has advantages over the AOCS procedure: it is more sensitive and gives quantitative results for individual free fatty acids. This new procedure also has several advantages over the modified BF₃/MeOH esterification procedure: it is easily and more rapidly performed, there is no deposition of glyceride on the column when the sample is injected, and because there is quantitative recovery, the new procedure is more sensitive and can be used on oils with a low weight percentage of free fatty acids.     

Fatty acid and glyceride composition of jubaea spectabilis palm oil

Determination of the fatty acid distribution in three samples of oil from the kernels of the palmJubaea spectabilis shows that the uniquely low melting point of the oil is due to a higher content of shorter chain fatty acids than other members of the subclass Cocoideae.     

Cyclic fatty acids from linolenic acid

Linolenic acid of 95% purity was heated with excess alkali in ethylene glycol to produce cyclic fatty acids. Reaction variables, which are associated with the cyclization reaction and which were investigated, included solvent-to-fatty-acid ratio, catalyst concentration, and reaction temperature, headspace gas (N₂ or C₂H₄), and head-space gas pressure. Yields of cyclic acids were improved by increasing solvent ratio (1.5–6 wt basis), reaction temperature (225–295C), and catalyst concentration (10–100% excess). With nitrogen the optimum catalyst concentration was about 100% excess, but when ethylene was used, no increase was obtained beyond 50% excess catalyst. Yields of polymeric acids produced in the reaction generally decreased as cyclic acid yields increased, except in one instance. Higher yields of cyclic fatty acids were obtained with ethylene than with nitrogen under all comparable conditions, and increasing the ethylene pressure to as high as 500 psi improved the yield. Ethylene adds to the conjugated double bonds and is believed to give C₂₀ fatty acids having a 1,4-disubstituted monoene ring in the chain. The maximum yield of monomeric cyclic acids from 95% linolenic acid was 84.6%, the balance being polymeric and unreacted monomeric acids. Monomeric acids from this test contained 95% cyclic acids. Presented at AOCS meeting, New Orleans, 1962. No. Utiliz. Res. & Dev. Div., ARS, U.S.D.A.     

Carotinanalysen in rohem Palmöl

Analysis of Carotenes in Crude Palm Oil Structure and properties of natural carotenes as well as their behaviour especially towards adsorbents are discussed. Literature on the occurrence of carotenes in palm oil is reviewed and a short history of the development of analytical methods for the separation of carotenes is presented. A tentative method of the DGF for the analysis of minor components is reported, which enables quantitative determination of the total carotenes as well as α and β-carotenes, separately in fats and oils. Usefulness of this method is shown in the analysis of 10 samples of crude palm oil from various sources. Determination of free fatty acids and peroxides round up the analytical picture of palm oil samples.