Phase equilibria of long-chain polyunsaturated fish oil fatty acid ethyl esters and carbon dioxide,ethane, or ethylene at reduced gas temperatures of 1.03 and 1.13

Phase equilibria of a mixture of long-chain polyunsaturated fish oil fatty acid ethyl esters (FAEEs) with carbon dioxide were measured at 313.2 and 343.2 K, with ethane at 314.0 and 344.6 K, and with ethylene at 290.9 and 318.6 K. The temperatures correspond to reduced gas temperatures of approximately 1.03 and 1.13. The experimental pressures range from 1.6 to 25 MPa. The FAEE mixture is rich in eicosapentaenoic acid ethyl ester (EPA, 52.5 wt.%), and docosahexaenoic acid ethyl ester (DHA, 36.1 wt.%), and a total of 10 components were identified. The experimental temperatures, pressures, solubilities, mass fractions, and calculated equilibrium ratios are reported in tables and graphs. The mass fractions and the equilibrium ratios are reported on a solvent-free basis.     

Aalysis of the fatty acid composition of the lipid classes in human blood serum under normal diet and when supplemented with fish oil

Total lipids have been extracted from human serum with chloroform–methanol 2:1 (v/v) and separated into individual classes by TLC. After transesterification the fatty acid methyl esters were analyzed by capillary gas chromatography on an FFAP column. The quantitation of ω-3 fatty acids has been performed using internal and external standards. Internal lipid standards for each lipid class were carried throughout the entire analytical procedure. Under normal diet eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) are incorporated into the lipid classes to different extents: cholesterol esters; EPA, 6.5 ± 1.9 γ/ml serum; DHA, 4.3 ± 1.9 μg/ml: phospholipids; EPA, 5.9 ± 2.7 μg/ml; DHA, 31.8 ± 8.1 μg/ml. Fish oil supplementation leads to a 4 to 6-fold rise in EPA and to an approximately 2-fold rise in DHA.     

毛细管气相色谱法测定深海鱼油中的EPA和DHA含量

用氢氧化钾－甲醇酯化法将深海鱼油中的脂肪酸快速、有效地转化成脂肪酸甲酯,然后进行毛细管气相色谱法测定,以二十二碳饱和脂肪酸甲酯为内标物,建立了5,8,11,14,17－二十碳五烯酸（EPA）和4,7,10,13,16,19－二十二碳六烯酸（DHA）的定量分析方法,并用于实际样品分析。该方法对EPA和DHA定量分析的相对标准偏差分别为4．6％和5．0％,回收率分别为99．7％和99．4％。     

Syntheses of some polyunsaturated sulfur- and oxygen-containing fatty acids related to eicosapentaenoic and docosahexaenoic acids.

With the aim of enhancing selectively the beneficial biological effects of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) a number of polyunsaturated fatty acids containing sulfur or oxygen atoms in the chain has been synthesized starting from EPA and DHA, respectively. Oxidative degradation of these acids led to the corresponding aldehydes all-(Z)-3,6,9,12-pentadecatetraenal and all-(Z)-3,6,9,12,15-octadecapentaenal. Reactions with DBU converted these aldehydes quantitatively into the conjugated isomers (2E,6Z,9Z,12Z)-pentadecatetraenal and (2E,6Z,9Z,12Z,15Z)-octadecapentaenal, respectively. The four aldehydes were transformed by a sequence of reactions comprising reduction to the alcohols, halogenation and substitution with mercapto esters into the corresponding sulfur containing polyunsaturated fatty acid esters. The oxygen containing esters were prepared from the respective alcohol by boron trifluoride catalysed reaction with ethyl diazoacetate.     

Analysis of polyunsaturated fatty acids in blood serum after fish oil administration.

Free and total fatty acids in the blood serum of patients with hyperlipoproteinemia have been analysed as their methyl esters by capillary gas chromatography using an FFAP column. In one-step reactions the free fatty acids in serum react with methanol-acetyl chloride (50:1, v/v) at 25 degrees C, the total fatty acids (free plus esterified) are transesterified with methanol-toluene-acetyl chloride (8:2:1, v/v) at 100 degrees C. The quantification of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) is based on an internal standard (13,16,19-docosatrienoic acid) and on calibration standards. Under normal diet the concentrations of EPA and DHA are as follows (mean +/- S.D., n = 27): free EPA, 0.2 +/- 0.1 mg/dl; free DHA, 0.6 +/- 0.2 mg/dl; total EPA, 3.6 +/- 2.1 mg/dl; total DHA 11.4 +/- 3.1 mg/dl. Under a fish oil intake of 9 g per day, free and total EPA concentrations rise by ca. five- to six-fold, and free and total DHA concentrations by ca. two-fold.     

Efficient lipase-catalyzed synthesis of new lipid antioxidants based on a catechol structure

Lipid antioxidants phenolic saturated fatty acid esters were synthesized in high yields and short reaction times using the corresponding ethyl fatty acid esters, lipase from Candida Antarctica, vacuum and no solvent. Phenolic esters with mono- and polyunsaturated fatty acids (EPA and DHA) were also prepared.     

Lipase-catalyzed interesterification of soybean oil with an omega-3 polyunsaturated fatty acid concentrate prepared from sardine oil

To reduce the content of linoleoyl moiety in soybean oil, soybean oil that contains 53.0% linoleoyl moiety as molar acyl moiety composition was interesterified with an omega-3 polyunsaturated fatty acid (PUFA) concentrate (24.0 mol% eicosapentaenoic acid [EPA], 40.4 mol% docosahexaenoic acid [DHA]) prepared from sardine oil, using an immobilized sn-1,3-specific lipase from Rhizomucor miehei (Lipozyme IM). The reaction was carried out in a batch reactor at 37 degrees C under the following conditions: 500 micromol of soybean oil, molar ratio of omega-3 PUFA concentrate to soybean oil = 1.0-6.0,5.0 mL of heptane, and 30 batch interesterification units of enzyme. After the reaction time of 72 h, modified soybean oil, which contains 34.9% linoleoyl, 10.1% eicosapentaenoyl, and 14.2% docosahexaenoyl moieties, was produced at the molar reactant ratio of 6.0. In this oil, the total omega-3 acyl moiety composition reached 34.1%; the molar ratio of omega-3 to omega-6 acyl moieties was enhanced by five times compared with soybean oil. Compared with palmitic acid, DHA was kinetically six times less reactive, although the EPA was by 16% more reactive.     

Zinc Ion Doped Solid-Phase Extraction of Eicosapentaenoic Acid and Docosahexaenoic Acid from Antarctic Krill

Antarctic krill crude extracts contain high levels of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). Accordingly, the solid phase extraction of EPA and DHA from Antarctic krill crude extracts has attracted significant research interest. This study compared the extraction of EPA and DHA from Antarctic krill crude extracts using an aminopropyl, zinc ion-doped silica, and C₁₈ and zinc ion-doped C₁₈ solid-phase column. The best extraction effect was obtained using the zinc ion-doped C₁₈ SPE with water containing methanol as the eluant. The efficiency increased gradually with increasing methanol concentration from 12.5 to 25% in the washing stage, and when pure methanol (5.0 mL) or acetonitrile (3.0 mL) was used as the eluant. To detect EPA and DHA, the acids were first converted to their methyl esters and detected by gas chromatography with flame ionization detection (GC–FID). In the zinc ion-doped C₁₈ elution fractions, EPA and DHA were isolated from the crude extracts in high yield (85–91% (r² = 4.8–6.3%)).     

Enrichment of eicosapentaenoic acid and docosahexaenoic acid from sardine by-products by supercritical fluid fractionation

Based on the principle of supercritical chromatography, a fractionation process for fatty acid methyl esters (FAMEs) under supercritical conditions was studied with the aim of obtaining in extracts highly enriched eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) from fish cannery waste. Yields of the fractionation process were enhanced by using adjuvant material and modifying CO(2) volumetric density and temperature. The combination of adjuvant properties with optimized pressure and temperature conditions permitted efficient fractionations of FAMEs, according to chain length and degree of unsaturation, in high purity (up to 95% of FAME) and good yields (45% of EPA and DHA starting potential). This work shows how green technologies, such as supercritical processes, can constitute a good alternative to the use of organic solvents in classical methods for valorisation of complex food industry waste.     

高效液相色谱法分离制备鱼油中的EPA和DHA

采用反相高效液相色谱技术,以μ－ＢｏｎｄａｐａｋＣ１８作固定相,ＣＨ３ＯＨ／ＴＨＦ／Ｈ２Ｏ作流动相,对鱼同中的二十碳五烯酸（ＥＰＡ）和二十二碳六烯酸（ＤＨＡ）进行了分离纯化,制备溶液经减压蒸馏,乙酸乙酯萃取后所得ＥＰＡ和ＤＨＡ质量分数可分别达到９８％和８６％以上。     

Partial Molar Volumes of Phenylacetic Acid and Several Polysubstituted Benzenes at Infinite Dilution in Water at Temperatures T = 298 to 373 K and at Pressures up to 30 MPa

Density data for dilute aqueous solutions of phenylacetic acid, benzene-1, 2-dicarboxylic acid (phtalic acid), benzene-1,2,4-tricarboxylic acid and 1,2,3-trihydroxy- benzene (pyrogallol) are presented together with the partial molar volumes at infinite dilution calculated from the experimental data. The measurements were performed at temperatures from T=298.15 K up to T=373.15 K and at three pressures up to 30 MPa. The data were obtained using a high-temperature, high-pressure flow vibrating-tube densimeter.     

Measurements of binary diffusion coefficients, retention factors and partial molar volumes for myristoleic acid and its methyl ester in supercritical carbon dioxide.

The binary diffusion coefficients, D(12), and retention factors for myristoleic acid and its methyl ester at infinite dilution were measured by the chromatographic impulse response technique in supercritical carbon dioxide at temperatures of 313.2, 333.2 and 343.2 K and pressures from 9.2 to 30 MPa for the acid, and from 8.0 to 14 MPa for the ester. Although the D(12) values were represented by the two correlations, the D(12)/T vs. CO(2) viscosity and the Schmidt-number correlations, which are valid for more than 40 compounds that we have measured so far, significant temperature dependences were observed for the ester. Moreover, the D(12) values for the ester at 313.2 K downward deviated from the background values around 400 kg m(-3), where the partial molar volumes, obtained from the correlation between the retention factors measured and CO(2) densities, showed large negative values.     

Optimized Analytical Conditions for Eicosapentaenoic and Docosahexaenoic Acids in Antarctic krill Using Gas Chromatography

A simple method for the esterification of EPA and DHA in Antarctic krill was developed. When EPA and DHA standard solution (1.0 mg/mL in acetonitrile) reacted with equal volumes of 0.5% sulfuric acid-methanol at 60°C for 30 min, approximately 100% esterification conversion of EPA and DHA was achieved. Based on the esterification of EPA and DHA in Antarctic krill extraction solutions under these optimization conditions, the concentrations of EPA and DHA in fresh Antarctic krill were, respectively, 4.87 and 4.26 mg/g in the head, and 2.79 and 2.62 mg/g in the pleon. In the freeze-dried Antarctic krill, the amount of EPA and DHA were, respectively, 27.80 and 24.68 mg/g in the head, and 19.89 and 18.46 mg/g in the pleon.     

Preparation of Triacylglycerols Rich in Omega-3 Fatty Acids from Sardine Oil Using a Rhizomucor miehei Lipase: Focus in the EPA/DHA Ratio

The increasing evidence on the differential biochemical effects of eicosapentaenoic acid (EPA)/docosahexaenoic acid (DHA) raises the need of n-3 highly unsaturated fatty acid concentrates with different amounts of these fatty acids. In the present work, physicochemical and enzymatic techniques were combined to obtain acylglycerols, mainly triacylglycerols (TAG), rich in n-3 fatty acids. Sardine oil was obtained by washing sardine (Sardina pilchardus) mince with a NaHCO₃ solution, hydrolyzed in a KOH–ethanol solution, and concentrated with urea. The esterification reaction was performed in the stoichiometric proportion of substrates for re-esterification to TAG, with 10 % level of Rhizomucor miehei lipase based on the weight of substrates, without any solvent, during 48 h. This procedure led to approximately 88 % of acylglycerols, where more than 66 % were TAG and the concentration of n-3 fatty acids was higher than 60 %, the EPA and DHA ratio (EPA/DHA) was 4:1. The content of DHA in the unesterifed fraction (free fatty acids) increased from 20 to 54 %, while the EPA level in the same fraction decreased from 33 to 12.5 % (EPA/DHA ratio ≈1:4). Computational methods (density functional theory calculations) have been carried out at the B3LYP/6-31G(d,p) level to explain some of the experimental results.     

Standard Molar Volumes and Heat Capacities of Aqueous Solutions of Trifluoromethanesulfonic Acid at Temperatures up to 573 K and Pressures to 30 MPa

Densities and heat capacities of dilute aqueous solutions (0.025 to 0.4 mol⋅kg⁻¹) of trifluoromethanesulfonic acid (triflic acid) were measured with original high-temperature, high-pressure instruments at temperatures and pressures up to 574 K and 31 MPa, respectively. Standard molar volumes and standard molar heat capacities were obtained via extrapolation of the apparent molar properties to infinite dilution. The evolution of these standard derivative properties of triflic acid with temperature and pressure is qualitatively compared with that of other acids of different strengths.     

混合超临界流体的密度及分子间相互作用

在３０８．１５Ｋ、６－１２ＭＰａ范围内,测定了ＣＯ２及ＣＯ２－正戊烷、ＣＯ２－正庚烷二元混合流体的密度,并计算了溶质的偏摩尔体积．在此基础上,将偏摩尔体积与ＭｏｎｔｅＣａｒｌｏ分子模拟研究相结合,研究了ＣＯ２－正戊烷、ＣＯ２－正庚烷二元系中的分子间相互作用和溶液的结构随压力和密度的变化．     

The direct determination of partial molar volumes and reaction volumes in ultra-dilute non-reactive and reactive multi-component systems using a combined spectroscopic and modified response surface model approach

Two experimental multi-component organometallic systems were studied, namely, (1) a non-reactive system consisting of [Mo(CO)(6)], [Mn(2)(CO)(10)], and [Re(2)(CO)(10)] in toluene under argon at 298.15 K and 0.1 MPa and (2) a reactive system consisting of [Rh(4)(CO)(12)] + PPh(3)--> [Rh(4)(CO)(11)PPh(3)] + CO in n-hexane under argon at 298.15 K and 0.1 MPa. The mole fractions of all solutes were less than 140 x 10(-6) in system (1) and less than 65 x 10(-6) in system (2). Simultaneous in-situ FTIR spectroscopic measurements and on-line oscillatory U-tube density measurements were performed on the multi-component solutions. A newly developed response surface methodology was applied to the data sets to determine the individual limiting partial molar volumes of all constituents present as well as the reaction volume. The limiting partial molar volumes obtained for system (1) were 176.4 +/- 2.5, 265.1 +/- 2.4, and 276.8 +/- 2.4 cm(3) mol(-1) for [Mo(CO)(6)], [Mn(2)(CO)(10)], and [Re(2)(CO)(10)], respectively and are consistent with independent binary experiments. The limiting partial molar volumes obtained for system (2) were 310.7 +/- 2.7, 219.8 +/- 2.2 and 461.5 +/- 4.5 cm(3) mol(-1) for [Rh(4)(CO)(12)], PPh(3) and [Rh(4)(CO)(11)PPh(3)], respectively. In addition, a reaction volume Delta(r)V equal to -17.0 +/- 5.7 cm(3) mol(-1) was obtained. The present results demonstrate that both partial molar volumes and reaction volumes can be obtained directly from multi-component organometallic solutions. This development provides a new tool for physico-chemical determinations relevant to a variety of solutes and their reactions.     

Volumes of aqueous alcohols, ethers, and ketones to T = 523 K and p = 28 MPa.

Densities of dilute aqueous solutions of isopropanol, 1,5-pentanediol, cyclohexanol, benzyl alcohol, diethyl ether, 1,2-dimethoxyethane, acetone, and 2,5-hexanedione were measured by means of a vibrating-tube flow densimeter at temperatures near T = (302, 373, 423, 473, and 521) K at a pressure of p = 28 MPa. At the lowest and highest temperatures, measurements were also made close to the saturation vapour pressure of water to investigate the effect of pressure on the volumes of solutes. Apparent molar volumes were calculated for each solute and extrapolated to give partial molar volumes at infinite dilution. The variation of the volume with temperature, pressure, and structure of solute is discussed qualitatively, and group contributions are determined at the temperatures of measurements and p = 28 MPa. Several equations proposed in the literature for correlating the partial molar volumes at infinite dilution as a function of state parameters are tested. Parameters of one selected equation are tabulated allowing calculation of the partial molar volumes at infinite dilution at temperatures and pressures up to T = 573 K and p = 40 MPa. respectively.     

Effect of Molecular Size of Solutes on Their Partial Molar Volumes in Supercritical n-Pentane

Supercritical fluids (SCFs) have many unique properties1. However, nearly all of the features are related with the aggregation or clustering of the molecules in the fluids. Some researchers have reported that the partial molar volumes (PMVs) of the solutes in dilute supercritical (SC) solutions are large negative values1-4, which is different from common liquid solutions. Negative PMV of a solute in SC solution results from the fact that the local density of the solvent surrounding the so…     

Enantioselective [4+2]-cycloaddition reaction of a photochemically generated o-quinodimethane: mechanistic details, association studies, and pressure effects

1,2,3,4-Tetrahydro-2-oxoquinoline-5-aldehyde (2) was prepared from m-aminobenzoic acid and 3-ethoxyacryloyl chloride (4) in 19 % overall yield. Compound 2 underwent a photochemically induced [4+2]-cycloaddition reaction with various dienophiles upon irradiation in toluene solution. The exo product 10 a was obtained with acrylonitrile (9 a) as the dienophile, whereas methyl acrylate (9 b) and dimethyl fumarate (9 c) furnished the endo products 11 b and 11 c (69-77 % yield). The reactions proceeded at -60 degrees C in the presence of the chiral complexing agent 1 (1.2 equiv) with excellent enantioselectivity (91-94 % ee). The enantiomeric excess increases in the course of the photocycloaddition as a result of the lower product association to 1. The intermediate (E)-dienol 8 was spectroscopically detected at -196 degrees C in an EPA (diethyl ether/isopentane/ethanol) glass matrix. The association of the substrate 2 to the complexing agent 1 was studied by circular dichroism (CD) titration. The measured association constant (K(A)) was 589 M(-1) at room temperature (25 degrees C) and normal pressure (0.1 MPa). An increase in pressure led to an increased association. At 400 MPa the measured value of K(A) was 703 M(-1). Despite the stronger association the enantioselectivity of the reaction decreased with increasing pressure. At 25 degrees C the enantiomeric excess for the enantioselective reaction 2 + 9 a-->10 a decreased from 68 % ee at 0.1 MPa to 58 % ee at 350 MPa. This surprising behavior is explained by different activation volumes for the diastereomeric transition states leading to 10 a and ent-10 a.