Detection of 430 Fatty Acid Methyl Esters from a Transesterified Butter Sample

Milk fat is known to contain one of the highest number of fatty acids of all edible oils. Some of these fatty acids are known to be valuable (e.g. conjugated linoleic acids, furan fatty acid) and other as undesirable (e.g. saturated and some trans-fatty acids) food ingredients. However, a comprehensive picture on the presence of many trace fatty acids has not been achieved. For this reason we have developed an analysis scheme based on the conversion of the fatty acids into methyl esters. The fatty acid methyl esters were then fractionated by urea complexation. Both the filtrate of the urea complexation (~4 % of the sample weight) and the original sample were fractionated by high-speed counter-current chromatography (HSCCC). The resulting fractions were analyzed by GC/MS analysis. With this method 430 fatty acids were detected in one single butter sample. More than 230 fatty acids had two or more double bonds. In addition to the widely known spectrum of fatty acids we also detected a range of cyclohexyl fatty acids (five homologues) and methyl-branched fatty acids (including short chain and even-numbered anteiso-fatty acids), conjugated tetradecadienoic acids along with the novel ω-oxo-fatty acids (seven homologues). The reported relative retention time on the polar column may serve as a data base for the screening of other samples for this profusion of fatty acids.     

棕榈油生物柴油脂肪酸甲酯气相色谱-质谱分析

采用气相色谱-质谱法,以11酸甲酯为内标,定性、定量分析了棕榈油制备的生物柴油中主要脂肪酸甲酯的分布及含量,结果表明:脂肪酸甲酯在各自质量浓度范围内,其峰面积与内标峰面积之比分别与甲酯浓度和内标浓度之比有良好的线性(r≥0.999 3).回收率在98.3 %～101.4 %之间(n =5), 精密度实验中相对标准偏差＜3 %(n =5).     

High-Throughput Analysis of Plasma Fatty Acid Methyl Esters Employing Robotic Transesterification and Fast Gas Chromatography

Fatty acid analysis is an important research tool, and indices derived from essential fatty acid contents serve as useful biomarkers related to cardiovascular and other chronic disease risk. Both clinical and basic studies of essential fatty acid composition are becoming ever larger in magnitude leading to delays while the rather laborious lipid analyses are performed. A robotic transesterification procedure has been developed for high-throughput analysis of plasma fatty acid methyl esters. In this approach, robots perform most steps including plasma and reagent transfer, transesterification reaction via heating at 80 °C in open tubes with multiple reagent additions, followed by two-phase extraction and transfer of lipid extracts to GC vials. The vials are then placed directly onto a GC autosampler carousel for robotic sample injection. An improved fast GC method is presented in which the peaks of interest are eluted within 6 min. This method is readily scalable to prepare and analyze 200 samples per day (1,000 samples per week) so that large clinical trials can be accommodated. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Producing Fatty Acid Methyl Esters from Free Fatty Acids with Ionic Liquids as Catalyst

Three Brønsted acidic imidazole dicationic ionic liquids (ILs) with different length of alkyl chains, [C_n(Mim)₂][HSO₄]₂ (n = 3, 6, 12), were prepared and used as catalyst for the esterification reaction of free fatty acids and methanol. Taking oleic acid as model acid, the catalytic performances of the synthesized ILs for the esterification were evaluated. The main physicochemical properties of the ILs, thermal stability, acidity, solubility in common solvents, and causticity on Austenitic stainless steel 316, were examined. [C₃(Mim)₂][HSO₄]₂ demonstrated the highest catalytic activity and enabled to assess the preliminary optimum esterification condition of oleic acid and methanol. Under optimized reaction conditions, the yield of oleic acid methyl ester was up to 95 %. The ILs have great potential as catalysts for producing fatty acid methyl esters from long‐chain free fatty acids.     

甲基葡萄糖苷脂肪酸酯的合成与研究

以碱性化合物CT作为催化剂,采用甲基葡萄糖苷和十八酸为原料合成甲基葡萄糖苷硬脂酸酯,对影响反应的主要因素进行了分析,通过IR分析不同反应条件下合成产品的组成,得到较优的反应条件为:n(甲基葡萄糖苷)∶n(十八酸)=1∶1.4,催化剂CT用量为甲基葡萄糖苷质量的0.6%,反应温度控制在150℃左右,反应压力0.01MPa,产品收率可以达到85%,颜色较浅。     

连续反应精馏合成C_(16～18)混酸甲酯的研究

在ｄ２２ｍｍ×ｌ１４００ｍｍ的玻璃填料塔中,以硫酸为催化剂,Ｃ１６～１８混合脂肪酸和甲醇为原料,对反应精馏合成混合脂肪酸甲酯的过程进行了研究,考察了各操作参数对脂肪酸转化率的影响。适宜的工艺条件是：催化剂用量为脂肪酸质量的１．１％,醇酸摩尔比为４．６,回流比为５,相应的脂肪酸转化率为９７．６％。     

微通道中合成环氧脂肪酸甲酯

采用盐酸H2O2/HCOOH法,在微通道反应器内对不饱和脂肪酸甲酯进行环氧化反应。考察了双氧水用量、甲酸用量、反应温度及催化剂用量对反应的影响,得到最优的反应条件为:m(脂肪酸甲酯):m(甲酸):m(双氧水)=1:1.5:2,反应温度40℃,催化剂浓盐酸质量分数为3%(即浓盐酸质量占原料脂肪酸甲酯质量的百分数,下同),反应时间为110 s。在该条件下,产品环氧值为4.32%。     

脲包法分离不饱和脂肪酸甲酯的研究

以混合脂肪酸甲酯为原料,采用尿素包合法（脲包法）分离不饱和脂肪酸甲酯。通过正交试验,得到了最佳工艺条件：混合脂肪酸甲酯（w）：尿素（w）：甲醇（v）为1：2．09：8．36,包合温度-10℃,包合时间18h。经过一次包合,不饱和脂肪酸甲酯的含量由原来的47．69％提高到86．74％,收率54．19％。     

Isothermal Curing Kinetics of Epoxidized Fatty Acid Methyl Esters and Triacylglycerols

Plant oil triacylglycerols are attractive renewable resources for biobased epoxy resins. We investigated the curing kinetics of three model epoxidized fatty acid methyl esters and representative epoxidized triacylglycerols with varied epoxide functionalities and distributions in the presence of a latent cationic initiator. Isothermal differential scanning calorimetry (DSC) was used to analyze the curing kinetics of the epoxy systems, and kinetic parameters (i.e., rate constants, reaction orders) were determined. Both epoxidized fatty esters and triacylglycerols followed the autocatalytic curing mechanism, and the DSC data were analyzed according to the Kamal autocatalytic model. Epoxidized methyl linoleate (EMLO) had the highest maximum curing rate, followed by epoxidized methyl linolenate (EMLON), and epoxidized methyl oleate (EMO) had the lowest maximum curing rate. We conclude that EMLO with two epoxide groups has the highest reactivity in this curing system, while the EMO with one epoxide group has the lowest reactivity. For epoxidized triacylglycerols, epoxidized camelina oil had the highest curing reactivity at higher temperatures, followed by epoxidized linseed oil and soybean oil.     

不饱和脂肪酸甲酯环氧化工艺的研究进展

以催化剂体系为主线,综述了近年来化学法和脂肪酶法制备无毒增塑剂环氧脂肪酸甲酯的研究现状。对杂多酸和离子液体等化学催化体系和酶催化体系的优缺点进行了评述;集中讨论了脂肪酶催化法中氧载体、底物物质的量比、H2O2滴加速度、反应温度等因素对不饱和脂肪酸甲酯环氧化过程的影响规律;分析了脂肪酶的固载化技术以及存在的相关问题。指出寻找合适载体固载脂肪酶、提高脂肪酶的活性和稳定性、探寻适宜的环氧化工艺条件、提高脂肪酶的利用率是下一步的开发方向。     

Simultaneous Analysis of Mono-, Di-, Triacylglycerols,and Fatty Acid Methyl Esters in Biodiesel by Size-Exclusion Chromatography

The purpose of this study is to develop and validate a method based on size-exclusion chromatography (SEC) for the simultaneous determination of fatty acid methyl esters (FAME), monoacylglycerols (MAG), diacylglycerols (DAG), and triacylglycerols (TAG) in biodiesel. The proposed method presents good linearity. The limits of detection are 0.26% mass for FAME, 0.02% mass for MAG, 0.01% mass for DAG, and 0.02% mass for TAG. The limits of quantification are 0.78% mass for FAME, 0.06% mass for MAG, 0.01% mass for DAG, and 0.06% mass for TAG. Accuracy evaluated by recovery yielded values ranging from 98.93% to 117.67%. Precision is evaluated by repeatability (%), which is ranged from 0.03% to 13.67%. The proposed SEC method proves effective in determining the FAME, MAG, DAG, and TAG content of standard samples, and the paired t-test shows that the results obtained were statistically similar to the gas chromatography (GC) values. The method also has some advantages over the reference GC methods, since it obtains the content for each class analyzed, irrespective of its components. Also, it does not require derivatization, which makes it easier and also quicker (15 min) than the 60 min taken by the two reference methods, and it does not need an internal standard, which makes it cheaper. Practical Applications: Size exclusion chromatography (SEC) is an efficient method for simultaneous and quantitative determination of fatty acid methyl esters (FAME), monoacylglycerols (MAG), diacylglycerols and triacylglycerols (TAG). The method present itself as an alternative to reference methods (ASTM D 6584 and ABNT NBR 15764) based on gas chromatography (GC). The proposed method shows advantages compared to reference methods, once it makes possible to determine the content of each constituent class in samples, regardless of its components, what makes the peak integration easier. Beyond that, previous sample derivatization is unnecessary, what makes the method simpler, cheaper and faster (15 min) than both reference methods that demands together 60 min for analysis (ASTM D 6584 for MAG, DAGa and TAG and ABNT NBR 15764 for FAME analysis).     

不饱和脂肪酸甲酯的绿色催化环氧化研究

选用氧化钼/叔丁基过氧化氢/阴离子离子液体{MoO3/TBHP/[bmimPF6]}(I)和氧化钼/过氧化氢/阴离子离子液体{MoO3/H2O2/[bmimBF4]}(II)两种绿色催化体系,探索了反应时间、反应温度、氧化剂/不饱和双键摩尔比和催化剂/不饱和双键摩尔比4个因素对不饱和脂肪酸甲酯环氧化转化率的影响。研究表明,实验条件下催化体系Ⅰ比催化体系Ⅱ具有更高的活性,MoO3可重复使用3次。     

Quantification of Nonanal and Oleic Acid Formed During the Ozonolysis of Vegetable Oil Free Fatty Acids or Fatty Acid Methyl Esters

The ozonolysis of unsaturated lipids is a process that has been used to generate aldehydes, acids, alcohols, and other biobased chemical intermediates. Reported here is a method that can be used to measure the formation of nonanal and oleic acid during the ozonolysis of unsaturated vegetable oil fatty acids or their methyl esters to indicate the extent of the ozonolysis reaction. Derivatization was performed using boron trifluoride in methanol solution to transform nonanal and oleic acid into nonanal dimethyl acetal and oleic acid methyl ester, respectively. Undecanal and 10‐heptadecenoic acid were used as internal standards and separation was performed using gas chromatography coupled with a flame ionization detector. The method was validated by performing a standard addition procedure in which nonanal or oleic acid standards were spiked into samples collected during the ozonolysis of oleic acid or canola oil fatty acid methyl ester (FAME). Linear regression results indicated that the measured nonanal and oleic acid are in good agreement with the actual amounts of nonanal and oleic acid added to the sample with at least 98 % recovery. The application of the method was demonstrated by the successful measurement of nonanal and oleic acid formed throughout the ozonolysis process for high oleic canola oil FAME.     

Structural Determination and Occurrence in Ahiflower Oil of Stearidonic Acid Trans Fatty Acids

Several marine oils and seed oils on the market contain relevant quantities of stearidonic acid (18:4n‐3, SDA). The formation of 18:4n‐3 trans fatty acids (tFA) during the refining of these oils necessitates the development of a method for their quantification. In this study, 18:4n‐3 was isolated from Ahiflower and isomerized to obtain its 16 geometric isomers. The geometric isomers of 18:4n‐3 were isolated by silver ion HPLC (Ag⁺‐HPLC) and characterized by partial reduction with hydrazine followed by gas chromatography analysis. The elution order of all 16 isomers was established using a 100 m × 0.25 mm 100% poly(biscyanopropyl siloxane) capillary column and at the elution temperature of 180 °C. The 4 mono‐trans‐18:4n‐3 isomers produced during the refining of oils rich in 18:4n‐3 were chromatographically resolved from each other, but c6,t9,c12,c15‐18:4 coeluted with the tetra‐cis isomer. These 2 fatty acids (FA) were resolved by reducing the separation temperature to 150 °C, but this change caused tetra‐cis‐18:4n‐3 to coelute with t6,c9,c12,c15–18:4. Combining the results from 2 isothermal separations (180 and 150 °C) was necessary to quantify the 4 mono‐trans 18:4n‐3 FA in Ahiflower oil.     

不饱和脂肪酸甲酯加氢Cu-Ni/SiO2催化剂的研究

针对铜镍二元催化剂活性低、难过滤及容易造成金属在加氢产物中残存等问题,开展了用于不饱和脂肪酸甲酯加氢的高活性、易过滤、低金属残存Cu Ni/SiO2催化剂的研究。以特制的、具有固定物性参数的SiO2做载体,是本催化剂的特点。通过控制铜镍比和不陈化解决了金属残存问题,且红外光谱表明,产物不发生异构。催化剂制备方法和条件为:并流沉淀,趁热过滤;铜镍总量与SiO2质量比为4∶1;铜镍质量比为1∶2 5;焙烧温度350℃左右,焙烧时间3h。该催化剂优点为:不需单独还原易于保存,反应速率快,加氢活性高,催化剂用量为甲酯质量的0 5%,1MPa氢压,反应30min条件下,产物碘值可由110降到5以下。     

A New Green Method for the Production Polyvinylchloride Plasticizers from Fatty Acid Methyl Esters of Vegetable Oils

The current work has shown the potentials for the aerobic oxidation of fatty acid methyl ester (FAME) of vegetable oils in the production of polyvinylchloride (PVC) plasticizers with the exclusion of other reagents. The reaction mixtures contain epoxidized derivatives of FAME, and esters, with the quantity of the ester groups being higher than in the initial raw material. It was established that the increase in the additional ester groups resulting from the “aerobic” Baeyer-Villiger (BV) reaction has a significantly positive influence on the plasticizing ability of the oxidized FAME mixtures for PVC when compared to the formation of epoxide compounds. The development of the technology for the production of PVC plasticizers proposed in this investigation provides an opportunity for resolving some of the environmental issues normally associated with the use of phthalate-based plasticizers.     

Fatty Acid Profile of Kenaf Seed Oil

The fatty acid profile of kenaf (Hibiscus cannabinus L.) seed oil has been the subject of several previous reports in the literature. These reports vary considerably regarding the presence and amounts of specific fatty acids, notably (12,13-epoxy-9(Z)-octadecenoic (epoxyoleic) acid, but also cyclic (cyclopropene and cyclopropane) fatty acids. To clarify this matter, two kenaf seed oils (from the Cubano and Dowling varieties of kenaf) were investigated regarding their fatty acid profiles. Both contain epoxyoleic acid, the Cubano sample around 2 % and the Dowling sample 5-6 % depending on processing. The cyclic fatty acids malvalic and dihydrosterculic were identified in amounts around 1 %. Trace amounts of sterculic acid were observed as were minor amounts of C17:1 fatty acids. The results are discussed in the context of the fatty acid profiles of other hibiscus seed oils.     

GC-MS法分析生物柴油中脂肪酸甲酯成分的研究

通过利用不同气相色谱-质谱条件对生物柴油中的脂肪酸甲酯成分的分析研究,优选一个 GC-MS 条件,选用PEG-20M的色谱柱,柱温用 150℃ 恒温,进样量为 0.2 μL,分析时间仅用了 12 min,能很好地分离和鉴定生物柴油中主要的10个脂肪酸甲酯,该方法可用于不同植物油制备的生物柴油样品中的脂肪酸甲酯成分的 GC-MS 分析。     

Molecular Weight Distribution of Low Molecular Weight Polyols Derived from Fatty Acid Methyl Esters

A series of commercial polyether polyols with well-defined molecular weights (MW) was used along with propylene glycol and dipropylene glycol as gel permeation chromatography (GPC) calibration standards to determine the MW and oligomeric composition of the synthesized low MW fatty acid methyl ester (FAME) polyols, having an MW of lower than 600 Da. This GPC analysis was compared to the one calibrated against the commercially-available polystyrene (PS) standards and to the number-average molecular weight (M _n) obtained via vapor pressure osmometry (VPO) technique. The MW of FAME polyols obtained with GPC calibrated against polyether polyols were closer to the M _n values obtained via VPO than the MW obtained via GPC calibrated against PS standards. Using the reliable GPC calibration, the MW distribution and the hydroxyl functionality of FAME polyols were determined with greater confidence.