A simple photometric method for microdetermination of fatty acids in lipids

A single step photometric micromethod for determination of fatty acids in lipids in benzene solution, using rhodamine 6G reagent, has been developed. The method eliminates the disadvantage of formation of a biphasic system and is applicable in the presence of glycerides, sterols, epoxy compounds, hydrocarbons and long chain hydroxy compounds such as long chain fatty alcohols. The long chain fatty acids from C₁₂ to C₂₂, both saturated and unsaturated, can be determined with reasonable accuracy in the concentration range of 0.08–0.25 μmole/ml. The method is simple, rapid, and requires relatively inexpensive chemicals.     

Acid-catalyzed alcoholysis ofVernonia galamensis oil

We have demonstrated the potential ofVernonia galamensis seed oil as a source of hydroxy alkoxy fatty esters. Reaction of the oil with various alcohols (methanol, ethanol, 1-propanol and 2-propanol), under acidic conditions, resulted in transesterification as well as epoxy ring opening in all cases. The major products, the hydroxy alkoxy fatty esters, constituted approximately 80% of the product mixtures, of which the 12-hydroxy-13-alkoxy isomers were the major constituents. These derivatives were isolated by solvent extraction and/or column chromatography to afford 78–80% of pure isomers. Alcoholysis with butanol resulted in a poor yield of the hydroxy butoxy esters. A discussion of the isolation and mass-spectrometric characterization of these new esters is provided.     

Supercritical fluid extraction of oil from millet bran

Proso millet bran [Panicum miliaceum (L.)], variety Dakota White, was extracted with supercritical carbon dioxide (SC-CO₂) to yield crude oil. The effects of operating parameters (pressure, temperature, and specific solvent flow) and of features of the raw material (moisture content and particle size) on oil extraction were investigated. Complete de-oiling of ground millet bran pellets was achieved under 300 bar at 40°C with a specific solvent flow of 2–10 h⁻¹ within 200 to 500 min. Solvent requirements were 20–30 kg CO₂/kg raw material. Composition of crude SC-CO₂ oil extracted under optimal conditions, i.e., fatty acid profile, amount of unsaponifiables, tocopherols, free fatty acids, sterols, sterol esters, waxes, hydrocarbons, and phospholipids, was compared to that of crude oil obtained by petroleum ether extraction. These two oils were similar in terms of fatty acid profile and amount of free fatty acids, unsaponifiables, peroxides, and tocopherols. They differed in respect to phospholipids (present in petroleum etherextracted oil and absent in SC-CO₂ extracted oil), metals, and waxes (lower levels in SC-CO₂ extracted oil). The effects of extraction procedures on oxidative stability of crude SC-CO₂ oil were studied. Ensuring that all pieces of the extractor in contact with the oil were in stainless steel; cleaning the separator, i.e., washing with KOH, rinsing, purging with N₂ and CO₂, and heating; performing a couple of extractions before the main extraction; and achieving the extraction without interruption all positively influenced the oxidative stability of the oil. Conversely, increasing CO₂ purity above 99.5% had no effect. Oxidative stability of the SC-CO₂ oil extracted under these conditions was only slightly lower than that of the oil extracted with petroleum ether.     

Extraction and Characterization of Seed Oil from Naturally Grown Chinese Tallow Trees

Seeds were collected from locally and naturally grown Chinese tallow trees (CTT) and characterized for general physical and chemical properties and fatty acid composition of the lipids. The effects of four different solvents (petroleum ether, hexane, diethyl ether, and 95 % ethanol) and two extraction methods (supercritical carbon dioxide (SC-CO₂) and conventional Soxhlet) on the properties of the CTT seed oil, including Chinese vegetable tallow (CVT) and stillingia oil (SO), were also investigated. In general, the yields of CVT and SO did not vary based on solvent for Soxhlet extraction and solvent-free SC-CO₂ extraction, except that the yield of CVT from SC-CO₂ extraction was substantially lower. Nevertheless, the CTT seed oil, extracted by SC-CO₂ displayed better quality than those extracted by Soxhlet extraction in terms of color, residual precipitation, and acid value of the oils. The pretreatment of CTT seed by 3 % aqueous sodium bicarbonate solution likely promoted the hydrolysis of triglyceride and caused the high acid value in the CVT samples. The iodine value at around 180 indicated that the SO is a highly unsaturated drying oil. Palmitic (76 %) and oleic (23 %) are two dominant fatty acids in CVT while linolenic (43 %), linoleic (31 %), and oleic (13 %) are the dominant fatty acids in SO.     

Epoxidized polyurethaneamide and polyesteramide as petroleum pipeline coatings

Linseed oil fatty acids were epoxidized by peracetic acid, then reacted with diethanolamine to give epoxidized hydroxy ethyl linseed oil fatty acid amide ( I ). This amide was rejected with toluene diisocyanate to produce epoxidized polyurethane-amide ( II ). Component I was also reacted with phthalic anhydride to give epoxidized polyesteramide ( III ). Resins II and III were evaluated as coating materials. The results obtained were compared with commercial epoxy resin, and show that resins II and III may be suitable to use as petroleum pipeline coatings.     

Die Dünnschicht-Chromatographie in der Wachsanalytik: Die Identifizierung der Wachsalkohole und -säuren

Thin-layer Chromatography in the Wax Analysis: The Identification of Wax Alcohols and Acids A thin-layer chromatographic method employing the following conditions has been developed for the separation of wax alcohols and acids. Adsorbent: Kieselgur G; impregnating solution: 0.5 vol% silicon oil + 10 vol% tetradecane in petroleum ether; stationary phase: tetradecane-silicon oil (Bayer PN 1000); C₁₄ to C₂₄: temperature 42° C; mobile phase: 90 vol% acetic acid, which is completely saturated with pure tetradecane at 42° C; C₂₂ to C₄₀: temperature 60° C; mobile phase: 96 vol% acetic acid, which is completely saturated with pure tetradecane at 60° C; detecting agent: 10% aqueous sodium hydroxide solution mixed with an equal volume of 0.1 molar (1.6%) aqueous potassium permanganate solution.     

The use of vegetable oils to recover compounds from aqueous solutions

Corn oil, canola oil, olive oil, sunflower oil, peanut oil and soyabean oil were tested as extractants for the recovery of organic compounds from aqueous solution. Short chain aliphatic alcohols and acids were poorly recovered (K_d < 1.0) while most esters, aldehydes and aromatic compounds tested were satisfactorily recovered (K_d > 2.0) from aqueous solution by vegetable oils. K_d is defined as the ratio of the concentration of the dissolved substance in the extractant to that in the aqueous phase. The exception was caffeine which was poorly extracted from water. The type of oil used appeared to have limited effect on K_d. Increasing the reaction temperature resulted in increased K_d for most readily extractable compounds. Acidulated fatty acid was also tested as an extractant. Although it generally resulted in a greater K_d than the oils or hexane control, acidulated fatty acid was less desirable as an extractant because it tended to create an emulsion with the aqueous phase under the test conditions.     

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.     

Synthesis and Surface Active Properties of Sulfonated Acrylate Esters Based on Al‐Cedre Oil

Sulfonated acrylate esters have been synthesized by using renewable raw materials such as fatty alcohols of Al‐Ceder oil. Mixed fatty acids were isolated from Al‐Ceder oil by hydrolysis; both saturated and unsaturated fatty acids were isolated from the mixed fatty acids. The methyl esters of mixed fatty acid, saturated and unsaturated acids of Al‐Cedre oil were subjected to reduction with (LiAlH4) to give the corresponding fatty alcohols. The products of the reduction process were saponified and the hydroxyl values were estimated to further confirm the reduction occurrence. The acrylate esters were synthesized by esterification of acrylic acid with fatty alcohols of C_16:0, C_18:0, C_18:1, and C_18:2 mixed saturated, mixed unsaturated and mixed fatty acids of Al‐Cedre oil, respectively. This esterification was followed by addition of NaHSO₃ to form bisulfite adducts. The structures of the prepared surfactants were characterized by IR and ¹HNMR spectroscopy. A series of useful surface parameters, stability towards acids and base hydrolysis and calcium stability have been determined.     

Effects of physical refining on contents of waxes and fatty alcohols of refined olive oil

Changes in the contents of waxes and fatty alcohols during deodorization/physical refining of bleached olive oil were studied. Experiments were carried out with 1.85% acidity oil, which was physically refined in a discontinuous deodorizer of 250-kg maximum capacity using nitrogen as stripping gas instead of steam. The variables studied were load and temperature of oil in the deodorizer as well as N₂ flow. Analyses of waxes and alcohols were carried out at different operation times. The maximum content of wax was always observed when the oil reached the deodorization temperature. The variation in the wax content depended on temperature and N₂ flow. Wax decomposition started and continued during the operating time, and a progressive decrease, which was pronounced between 3 and 4 h, was observed. Small changes in waxes were observed between 4 and 5 h. Total content of fatty alcohols diminished throughout the operating time, and changes did not depend on the variables studied.     

Lipase-catalyzed synthesis of hydroxy stearates and their properties

Hydroxy fatty acid (HFA) esters of long-chain alcohols, such as hydroxy stearates, have potential applications from lubricants to cosmetics. These esters were synthesized enzymatically to overcome the problems associated with chemical processes. An immobilized lipase, Rhizomucor miehei, was employed as catalyst in the esterification reaction between hydroxy-stearic acid as a source of HFA and monohydric fatty alcohols (C₈–C₁₈). The yields of esters were in the range of 82–90% by conducting the reactions at 65±2°C, 2–5 mm Hg pressure, and 10% lipase concentration. The products were analyzed by infrared spectroscopy, and some of their analytical characteristics were determined.     

Gas chromatographic identification of fatty acids,fatty alcohols,and hydrocarbons ofHibiscus rosa-sinensis leaves

Hibiscus rosa-sinensis leaves (family Malvaceae) were analyzed for their fatty acid, fatty alcohol, and hydrocarbon contents. Wax hydrocarbons ranging from C₁₆ to C₃₂ with C₂₃, C₂₅, C₂₇, and C₃₁ as major components and wax alcohols between C₂₁ and C₃₀ with C₂₆, iso-C₂₈, and iso-C₃₀ as major components were found to be present in the petroleum ether fraction of the leaves. Fatty acids ranging from C₈ to C₂₈ with C₈, C₁₂, C₁₄, C₁₆, and C_18:2 as major components were found in the combined form. Two cyclic acids, sterculic and malvalic, have also been identified.     

Chemical structure of long-chain esters from “sansa” olive oil

The major objective of this study was to determine the chemical structure of long-chain esters present in lower-grade olive oil. The classes of esters composing the hexanediethyl ether (99∶1) extract of the wax fraction from a pomace olive oil were: (i) esters of oleic acid with C₁−C₆ alcohols, (ii) esters of oleic acid with long-chain aliphatic alcohols in the range C₂₂−C₂₈ and (iii) benzyl alcohol esters of the very long-chain saturated fatty acids C₂₆ and C₂₈. The analysis and the structure assignments were carried out by gas chromatography coupled with mass spectrometry and by comparison with synthetic authentic model compounds. This work provided precise data on the chemical nature of the wax esters present in olive oil and should represent a means to detect adulteration of higher-grade olive oil with less expensive pomace olive oil and seed oils.     

Effects of processing on physicochemical properties and fatty acid composition ofhibiscus sabdariffa seed oil

Expeller pressed crudeHibiscus sabdariffa seed oil (mesta oil) is dark and most unappealing. On refining, the appearance of the oil is improved. The unusual fatty acids present in theH. sabdariffa seed oil, cyclopropene acids (malvalic C₁₈H₃₂O₂ and sterculic C₁₉H₃₄O₂) and epoxy oleic acid (C₁₈H₃₂O₃), are not reduced by refining. Partial hydrogenation did not reduce the epoxy oleic acid, but it eliminated the cyclopropene acids. Heating for 10 min was sufficient for complete elimination of cyclopropene acids, but heating up to 60 min did not affect the epoxy acid.     

Epoxidized soybean oil modified using fatty acids as tougheners for thermosetting epoxy resins: Part 2—Effect of curing agent and epoxy molecular weight

A series of bio-rubber (BR) tougheners for thermosetting epoxy resins was prepared by grafting renewable fatty acids with different chain lengths onto epoxidized soybean oil at varying molar ratios. BR-toughened samples were prepared by blending BRs with diglycidyl ether of bisphenol A resins, Epon 828 and Epon 1001F, at different weight fractions and stoichiometrically cured using an amine curing agent, 4, 4′-methylene biscyclohexanamine (PACM). Fracture toughness properties of the unmodified and BR toughened polymer samples—including critical strain energy release rate (G_Ic), and critical stress intensity factor (K_Ic)—were measured to investigate the toughening effect of prepared BRs. It was found that the degree of phase separation and toughening were more controllable relative to similar polymers cured using the aromatic curing agent Epikure W, and the use of higher molecular epoxy resins produces a synergistic effect increasing the toughness much more than similar polymers made with lower molecular weight epoxy resins. Average BR domain sizes ranging from 200 to 900 nm were observed, and formulations with G_Ic, values K_Ic as high as 1.0 kJ/m² and 1.4 MPa m^1/2 were attained respectively for epoxy systems with T_g greater than 130°C.     

Synthesis of Chloroalkoxy eicosanoic and docosanoic acids from meadowfoam fatty acids by oxidation with aqueous sodium hypochlorite

Chloroalkoxy substituted C₂₀ and C₂₂ fatty acids can be synthesized from the unsaturated fatty acids in meadow-foam oil by reaction of the fatty acids with primary or secondary alcohols and an aqueous sodium hypochlorite solution (commercial bleach). The reactions are conducted at room temperature for 3 h. Chlorohydroxy fatty acid derivatives are formed as by-products owing to the presence of water in the reaction mixture. Chlorinated δ-lactones are also produced by direct reaction of sodium hypochlorite with the Δ5 unsaturated fatty acids present in meadowfoam or by ring closure of the 6-chloro-5-hydroxy fatty acids. The product yield of chloroalkoxy fatty acids is dependent on the nature and volume of the alcohol used in the reaction, as well as the concentration and pH of the sodium hypochlorite solution. Primary alcohols such as methanol and butanol produce maximal yields (50–60%) of chloroalkoxy fatty acids whereas the secondary alcohol 2-propanol gives a 30% yield. Chloroalkoxy fatty acid yields can be increased to 75–80% by elimination of water from the reaction mixture through a procedure that partitions sodium hypochlorite from water into hexane/ethyl acetate mixtures. All of the reaction products were fully characterized using nuclear magnetic resonance and gas chromatography-mass spectrometry.     

Identification of TAG and DAG and their FA Constituents in Lesquerella (Physaria fendleri) Oil by HPLC and MS

Castor oil has many industrial uses because of its high content (90 %) of the hydroxy fatty acid, ricinoleic acid (OH¹²18:1⁹). Lesquerella oil containing lesquerolic acid (Ls, OH¹⁴20:1¹¹) is potentially useful in industry. Ten molecular species of diacylglycerols and 74 molecular species of triacylglycerols in lesquerella (Physaria fendleri) oil were identified by electrospray ionization mass spectrometry as lithium adducts of acylglycerols in the HPLC fractions of lesquerella oil. Among them were: LsLsO, LsLsLn, LsLsL, LsLn–OH20:2, LsO–OH20:2 and LsL–OH20:2. The structures of the four new hydroxy fatty acid constituents of acylglycerols were proposed by the MS of the lithium adducts of fatty acids as (comparing to those in castor oil): OH¹²18:2^9,14 (OH¹²18:2^9,13 in castor oil), OH¹²18:3^9,14,16 (OH18:3 not detected in castor oil), diOH^12,1318:2^9,14 (diOH^11,1218:2^9,13 in castor oil) and diOH^13,1420:1¹¹ (diOH20:1 not detected in castor oil, diOH^11,1218:1⁹ in castor oil). Trihydroxy fatty acids were not detected in lesquerella oil. The differences in the structures of these C18 hydroxy fatty acids between lesquerella and castor oils indicated that the polyhydroxy fatty acids were biosynthesized and were not the result of autoxidation products.     

The influence of fatty alcohol ether phosphate salt on carbon fiber's dispersion property

The influence of fatty alcohol ether phosphate salt on the dispersion property of carbon fiber in oil material is assessed by the settling time, the turbidity and the dispersant condition of carbon fiber in oil material, and the surface morphologic structure and chemical composition of carbon fiber before and after leaching silk are characterized by field emission scanning electron microscope, scanning tunneling microscope, and X‐ray photoelectron spectroscopy. Experiments show that fatty alcohol ether phosphate salt can improve the dispersion of carbon fiber in oil material significantly, and the optimum leaching silk concentration of fatty alcohol ether phosphate salt is 0.3%, while dispersants would spread over on the surface of carbon fiber evenly and the maximum turbidity value and the longest settlement time is 1.081 NTU and 28 min, respectively. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41470.     

A Nanoparticle Adsorption-Based Salt-Resistant Foam for Gas Well Deliquification

With the continuous development of gas fields, water production problems are seriously affecting production rates. Aiming at the problem of the high production rates of mineralized formation water in China's gas fields, we investigate the feasibility of a foam for gas well deliquification process using a combination of nanoparticles and surfactants. Through the combination of anionic and non-ionic surfactants, a system with better foam stability is optimized by the hand-shock method. Based on the formation of hydrogen bonds between the fatty alcohol polyoxyethylene ether and SiO₂ nanoparticles, the fatty alcohol polyoxyethylene ether created hydrophobicity after silica was added. Adsorbed on the gas–liquid interface, the dilatational modulus of the gas–liquid interface increased, the shift time extended, and the diameter of the generated foam is smaller, that is, a unit volume of gas can carry more liquid. Foam stability can be adjusted by altering the pH value of the foam for gas well deliquification. Last, the oil resistance of the system was improved by adding fatty alcohols. Here, a foam for gas well deliquification was established by the combination of surfactant, nanoparticles, and fatty alcohols, which has good foaming performance, stability, and oil resistance.