Separation of natural polyunsaturated fatty acids by means of lodolactonization

Conditions of the iodolactonization reaction (ILreaction) were optimized as a method for separation of natural polyunsaturated fatty acids. The effects of the solvent, temperature and the ratio of components of the iodizing complex KI/I₂ upon the rate of the synthesis of several iodolactones (ILs) in the IL-reaction are described. It was shown that the rate of formation of γ-ILs was significantly higher than that for δ-ILs. This offers opportunity for obtaining pure docosahexaenoic acid (DHA) from fatty acid (FA) concentrates. The possibility for selective reduction of δ-ILs in the presence of γ-ILs to yield pure arachidonic acid (AA) or eicosapentaenoic acid (EPA) or fatty acid concentrates has been demonstrated. Preparation of pure AA from a mixture of AA, DHA and other FAs by the IL-reaction without Chromatographie procedures is described.     

Influence of triacylglycerol characterics on the determination of free fatty acids in vegetable oils by fourier transform infrared spectroscopy

A rapid and direct Fourier transform infrared (FTIR) spectroscopic method using a 25-μm NaCl transmission cell was developed for the determination of free fatty acids (FFA) in six important vegetable oils (corn, soybean, sunflower, palm, palm kernel, and coconut oils) that differ in fatty acid profile. The calibrations were established by adding either standard FFA (oleic, lauric acids) or a representative mixture of FFA obtained after saponification of the refined oils. For all oils, up to a FFA level of 6.5% for coconut oil, the best correlation coefficient was obtained by linear regression of the free carboxyl absorption at 1711 cm⁻¹. All correlation coefficients were greater than 0.993, and no significant difference between the calibration methods could be detected. Upon validation of the calibration, no significant difference (α=0.05) between the “actual” and the “FTIR predicted” FFA values could be observed. The calibration models developed for the six oils differed significantly and indicate the need to develop a calibration that is specific for each oil. In terms of repeatability and accuracy, the FTIR method developed was excellent. Because of its simplicity, quick analysis time of less than 2 min, and minimal use of solvents and labor, the introduction of FTIR spectroscopy into laboratory routine for FFA determination should be considered.     

Enrichment of omega3 fatty acids from Tyulka oil by supercritical CO2 extraction

BACKGROUND: Supercritical CO₂ enrichment of omega3 essential fatty acids (FAs) from Tyulka oil, using a batch process was investigated. Fractional factorial design was applied to evaluate the effects of the five process parameters: pressure (20.26 to 25.33 MPa); temperature (40 to 50 °C); packing fraction (0.5 to 0.7); modifier fraction (2 to 5%); and dynamic time (15 to 25 min), and their binary interactions on the enrichment of extracted omega3 FAs. By employing experimental design and analysis of variance, the variables were evaluated according to the significance of their effect on the yield of extracted omega3. RESULTS: The experimental results confirmed that pressure and dynamic time were the most important factors affecting enrichment of omega3. The amount of modifier in the feed also showed an increasing effect on the response. The binary interaction effects were investigated, and are discussed in detail. CONCLUSION: Optimum conditions were found at 25.33 MPa, 46.65 °C, packing fraction 0.50, modifier 5% and dynamic time 25 min, improving the enrichment of omega3 FAs up to 2.9 times. Copyright © 2009 Society of Chemical Industry     

Solid‐phase extraction in combination with GC/MS for the quantification of free fatty acids in adipocere

Current research investigating the effect of specific aquatic microenvironments on the formation of adipocere using domesticated pigs (Sus scrofa) has demonstrated the need for a fast and reliable method to separate and identify fatty acids present in adipocere. Adipocere is defined as a late‐stage post‐mortem decomposition product consisting of a mixture of free fatty acids (FFA), which have formed under favorable conditions due to the hydrolysis of triglycerides in adipose tissue. Whilst good separations of adipocere lipids have been achieved using TLC, this method is time consuming when processing large numbers of samples. This paper describes a rapid and simple method for the extraction, identification and quantification of FFA commonly found in adipocere, by solid‐phase extraction (SPE) using aminopropyl disposable columns in combination with GC/MS. The recoveries of FFA associated with adipocere were all above 90%, with coefficients of variation below 10%, indicating that the technique was reproducible. The limits of quantification were registered at levels of parts per million. Standard curves were linear over the range of 50–1000 µg/mL, with all correlation coefficient values greater than 0.998. A marked increase in concentration of saturated fatty acids was observed during adipocere formation, ranging from 20 to 55% for palmitic acid, 13 to 23% for stearic acid and 2.8 to 4.1% for myristic acid. These results demonstrate the suitability of aminopropyl disposable SPE columns to efficiently and rapidly isolate FFA from adipocere prior to quantitative GC/MS analysis.     

Electron impact mass spectra of the oxazoline derivatives of some conjugated diene and triene C18 fatty acids

The location of the double-bond systems of some conjugated diene and triene C₁₈ fatty acids (C18∶2[9,11], C18∶2[10,12], C18∶3[9,11,13] and C18∶3[10,12,14]) derived from alkaline isomerization has been determined by gas chromatography/mass spectroscopy analysis of their 4,4-dimethyloxazoline derivatives. The positions of the double bonds were indicated by a characteristic mass separation of 12 atomic mass units for each olefinic bond. Furthermore, the structure assignments were supported by the presence of prominent formal allylic cleavage peaks.     

Rapid quantitative determination of free fatty acids in fats and oils by fourier transform infrared spectroscopy

Rapid direct and indirect Fourier transform infrared (FTIR) spectroscopic methods were developed for the determination of free fatty acids (FFA) in fats and oils based on both transmission and attenuated total reflectance approaches, covering an analytical range of 0.2–8% FFA. Calibration curves were prepared by adding oleic acid to the oil chosen for analysis and measuring the C=O band @ 1711 cm^–1 after ratioing the sample spectrum against that of the same oil free of fatty acids. For fats and oils that may have undergone significant thermal stress or extensive oxidation, an indirect method was developed in which 1% KOH/methanol is used to extract the FFAs and convert them to their potassium salts. The carboxylate anion absorbs @ 1570 cm^–1, well away from interfering absorptions of carbonyl-containing oxidation end products that are commonly present in oxidized oils. Both approaches gave results comparable in precision and accuracy to that of the American Oil Chemists’ Society reference titration method. Through macroprogramming, the FFA analysis procedure was completely automated, making it suitable for routine quality control applications. As such, the method requires no knowledge of FTIR spectroscopy on the part of the operator, and an analysis takes less than 2 min.     

磺酸基功能化C/Si材料催化合成短碳链结构磷脂

通过化学活化有机磺酸前驱体,低温下制备了磺酸基功能化碳/硅材料(C/Si-SO3H),并将其用于大豆卵磷脂与丙酸乙酯或丁酸甲酯催化合成短碳链结构磷脂的反应中,考察了反应温度、反应时间、催化剂用量及循环次数对该酯交换反应的影响.采用FTIR、Raman及Boehm酸含量滴定等手段对C/Si-SO3H进行结构和表面酸性质表征,以建立该催化剂的构效关系.结果表明,C/Si-SO3H表面含有大量Br?nsted酸性位点,因而催化性能较为突出;当催化剂用量为反应原料总质量的7％、40℃反应6 h,短碳链结构磷脂中丙酸或丁酸的接入率高达18.33％或16.23％,且C/Si-SO3H循环利用4次而无明显失活.     

Evaluation of commercial PTFE membranes in desalination by direct contact membrane distillation

In this study, nine flat-sheet commercially available hydrophobic PTFE membranes were used in desalination by direct contact membrane distillation and their characteristics were investigated under different operating conditions including feed temperature, feed flow rate, cold stream flow rate, and feed concentration. Membrane properties, i.e. pore size, thickness, support layer, and salt rejection were also studied. Moreover, membrane module designs including flow arrangements (co-current, counter-current and tangential) for process liquid and depth both on hot and cold sides were tested experimentally. Finally, the long-term performance of the selected membranes for direct contact membrane distillation as a stand-alone desalination process was investigated. The results indicated that increasing feed temperature, hot feed flow rate, and module depth on the cold side led to increase permeate flux. On the other hand, increasing membrane thickness and module depth on the hot side (at constant flow rate) had negative effects on the flux. The highest permeation flux and salt rejection was achieved when the membranes with a pore size of 0.22 μm were used in the cross-current follow arrangement of hot and cold streams. In addition, the requirements for support layer for a successful DCMD process has been extensively discussed.