南海Spirasterella中脂肪酸酯组分的鉴定

用色谱—质谱联用技术分析了中国南海海绵Spirasterella aurivilli Lindgren中脂肪酸酯组分。鉴定了29种脂肪酸酯,其中20种饱和脂肪酸乙酯,8种不饱和脂肪酸乙酯及1种饱和脂肪酸甲酯。并发现该海绵中含有自然界少见的10种奇数碳脂肪酸乙酯。     

Minor gamma-lactones from Trichilia catigua (Meliaceae) and its precursors by GC-MS

NMR and GC-MS analysis of fractions of the CHCl3 extract of Trichilia catigua bark led to the identification of a mixture of three omega-phenyl alkanes, three omega-phenyl alkanoic acids, five omega-phenyl-gamma-lactones, two alkyl-gamma-lactones, one alkenyl-gamma-lactone and a mixture of fatty acids ranging from C-14 to C-26. Beta-sitosterol, stigmasterol and campesterol as free alcohols were also identified.     

Rapid analysis of free medium-chain fatty acids and related ethyl esters in beer using SPE and HRGC

A modification of a procedure by Hage [1] is proposed for the gas chromatographic evaluation of the content of free medium-chain fatty acids and related ethyl esters in beer. The method involves extraction of free fatty acids and ethyl esters by SPE using C₁₈ bonded phase columns, derivatization of free fatty acids and related ethyl esters with diazomethane, and GC analysis using an SP-2340 capillary column. The results obtained have shown the method to be rapid and highly reproducible. The technique has been compared with other methods used for determination of free fatty acids.     

Rapid analysis of non-esterified fatty acids as methyl esters from different biological specimens by gas chromatography after one-step esterification

A rapid gas chromatographic method for the determination of medium-chain and long-chain free fatty acids (C14:0 to C24:0 fatty acids) from different biological specimens is presented. After a rapid one-step transesterification method in methanol-acetyl chloride (50:1, v/v), fatty acid methyl esters were extracted into n-hexane and analysed on a 15-m Durabond-Wax column within a 12-min chromatographic run. The detection limit is 500 pg per injection.     

Determination of fatty acid methyl esters derived from algae Scenedesmus dimorphus biomass by GC–MS with one‐step esterification of free fatty acids and transesterification of glycerolipids

Algae can synthesize, accumulate and store large amounts of lipids in its cells, which holds immense potential as a renewable source of biodiesel. In this work, we have developed and validated a GC–MS method for quantitation of fatty acids and glycerolipids in forms of fatty acid methyl esters derived from algae biomass. Algae Scenedesmus dimorphus dry mass was pulverized by mortar and pestle, then extracted by the modified Folch method and fractionated into free fatty acids and glycerolipids on aminopropyl solid‐phase extraction cartridges. Fatty acid methyl esters were produced by an optimized one‐step esterification of fatty acids and transesterification of glycerolipids with boron trichloride/methanol. The matrix effect, recoveries and stability of fatty acids and glycerolipids in algal matrix were first evaluated by spiking stable isotopes of pentadecanoic‐2,2‐d₂ acid and glyceryl tri(hexadecanoate‐2,2‐d₂) as surrogate analytes and tridecanoic‐2,2‐d₂ acid as internal standard into algal matrix prior to sample extraction. Later, the method was validated in terms of lower limits of quantitation, linear calibration ranges, intra‐ and inter‐assay precision and accuracy using tridecanoic‐2,2‐d₂ acid as internal standard. The method developed has been applied to the quantitation of fatty acid methyl esters from free fatty acid and glycerolipid fractions of algae Scenedesmus dimorphus .     

Measurement of free glycerol in biofuels

A method has been developed to determine the free glycerol content in esters derived from vegetable oils. After extraction of glycerol, its measurement in small quantities in biofuels (methyl or ethyl esters) is possible by high-pressure liquid chromatography combined with pulsed amperometric detection, HPLC-PAD. The method has proved to be simple, rapid and accurate. The limit of detection is 1 microg/g.     

气相色谱-质谱分析新种海绵Reniochalina sp.中的低极性组分

采用气相色谱-质谱联用技术（GC-MS）与核磁共振氢谱（1H-NMR）相结合的方法,对中国黄海肾指海绵属新种海绵Reniochalina sp.中的低极性组分进行了研究。实验首先采用环己烷对海绵进行提取,然后将提取液浓缩,用硅胶柱对其进行柱色谱分离。取乙酸乙酯-环己烷（体积比为1∶9）混合液梯度洗脱所得油状物用于连续两次制备色谱分离,得到两个样品,对其进行1H-NMR及GC-MS分析。此次实验共从该海绵中分离鉴定出10种链烃、2种脂肪酸、2种脂肪酸酯、邻苯二甲酸以及3种邻苯二甲酸二酯共18种化学成分。该研     

Isolation of chlorinated fatty acid methyl esters derived from cell-culture medium and from fish lipids by using an aminopropyl solid-phase extraction column

An aminopropyl-based solid-phase extraction technique was used for isolation of chlorinated fatty acids in lipids. A range of different chlorinated fatty acids was eluted in a small volume of solvent (4 ml) and the recoveries of the different species and isomers were quantitative. Only 1% of the vastly dominating unchlorinated fatty acid methyl esters were recovered in the fractions containing the chlorinated fatty acid methyl esters. This method makes it possible to isolate and detect > or = 1 microg of a chlorinated fatty acid methyl ester in 1 g of lipid.     

Identification by gas chromatography and mass spectrometry of lipids from the rat Harderian gland

Lipids from rat Harderian glands were extracted with ethyl acetate, hydrolysed with base and examined by gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS) as trimethylsilyl (TMS), [2H9]TMS, methyl ester-TMS, picolinyl, nicotinate and nicotinylidene derivatives. The latter three derivatives were used to reveal the structures of the alkyl chains of fatty acids, alcohols and glycerol ethers, respectively. Forty-eight compounds were identified, representing about 97% of the total extracted lipids as measured by GC peak areas. The major constituents were fatty acids with chain lengths from 12 to 22 carbon atoms (mainly C18 and C20) and fatty alcohols (C16 to C26) derived from wax esters. Most of these acids and alcohols were unsaturated in the omega-7 position and were accompanied by smaller amounts of the saturated and omega-5 monounsaturated analogues. glycerol ethers were also identified for the first time in this secretion; the ether chains contained from 14 to 19 carbon atoms (mainly 16) and were straight-chain saturated, unsaturated (omega-5 and omega-7) and branched (iso). The only sterol found was cholesterol amounting to 1.24% of the total extract.     

Phase and chemical equilibria in the transesterification reaction of vegetable oils with supercritical lower alcohols

Calculations of thermodynamic data are performed for fatty acid triglycerides, free fatty acids, and fatty acid methyl esters, participants of the transesterification reaction of vegetable oils that occurs in methanol. Using the obtained thermodynamic parameters, the phase diagrams for the reaction mixture are constructed, and the chemical equilibria of the esterification reaction of free fatty acids and the transesterification reaction of fatty acid triglycerides attained upon treatment with supercritical methanol are determined. Relying on our analysis of the obtained equilibria for the esterification reaction of fatty acids and the transesterification reaction of triglycerides attained upon treatment with lower alcohols, we select the optimum conditions for performing the reaction in practice.     

Rapid procedure for the isolation and analysis of fatty acid and fatty alcohol fractions from wax esters of marine zooplankton

A rapid and simple method for the isolation of fatty acid methyl esters and fatty alcohols from the lipid fraction of marine zooplankton is described. Wax esters are the dominant lipid class in most calanoid copepods and trans-esterification results in a high fatty alcohol content in the analytical extract. Current procedures for the separation and purification of lipid classes by preparative thin-layer chromatography are time-consuming and are subject to low recovery of the analytes. In this method, fatty acid methyl esters and fatty alcohols were separated by liquid chromatography using silica or honded amino-silica as the stationary phase. The procedure is equally applicable to the analysis of zooplankton with low wax ester (and hence fatty alcohol) content, for example, a number of species of euphausiid and, generally, for samples of low mass.     

Natural product propolis: chemical composition

The chemical composition of propolis from East Mediterranean (Hatay, Adana and Mersin) was studied in order to determine the major compounds by using GC-MS. In this study, the ethanolic extract of propolis prepared by mixing 1900mL 70% ethanol and 100g propolis was used. Chemical analysis of propolis extracts indicated that the propolis samples had high concentrations of the aromatic acids, esters and other derivatives which are responsible for the anti-bacterial, anti-fungal, anti-viral, anti-inflammatory and anti-cancer properties of propolis such as benzyl cinnamate, methyl cinnamate, caffeic acid, cinnamyl cinnamate and cinnamoylglcine besides the most common compounds as fatty acid, terpenoids, esters, alcohols hydrocarbons and aromatic acids.     

Fatty acids determination in Bronte pistachios by gas chromatographic method

A gas chromatographic with flame ionization detector (GC-MS FID) method for the identification and quantification of fatty acids based on the extraction of lipids and derivatisation of free acids to form methyl esters was developed and validated. The proposed method was evaluated to a number of standard FAs, and Bronte pistachios samples were used for that purpose and to demonstrate the applicability of the proposed method. In this regard, repeatability, mean and standard deviation of the analytical procedure were calculated. The results obtained have demonstrated oleic acid as the main component of Bronte pistachios (72.2%) followed by linoleic acid (13.4%) and showed some differences in composition with respect to Tunisian, Turkish and Iranian pistachios.     

Solid-phase extraction and determination of trace aroma and flavour components in cider by GC-MS

Summary Minor volatile compounds are responsible for the aromas of cider. A simple technique for the analysis of these components is described based on solid-liquid phase extraction followed by quantitation by gas chromatography-mass spectrometry (GC-MS). The method is quantitative for analysis of alcohols, esters, lactones, phenols, and medium and long chain-length fatty acid.     

Nonsaponifiable lipid components of the pollen of elder (Sambucus nigra L.).

Pollen of the elder (Sambucus nigra L.) was extracted with chloroform-methanol. The extract was separated by column chromatography into the following groups of compounds: hydrocarbons (8.7%). polycyclic aromatic hydrocarbons (0.2%), complex esters (5.2%), triglycerides (18.7%), hydroxy esters (27.9%), free fatty acids and alcohols (16.8%), free sterols (6.8%), and triterpenic alcohols (4.0%). The nonsaponifiable components (hydrocarbons, fatty acids, alcohols, and sterols) were examined in detail using spectroscopic and chromatographic methods (IR spectroscopy, GC, and GC-MS). The identified compounds were characterized by their mass spectra and Kováts retention indices. The double bond positions and their configurations in unsaturated compounds are also reported.     

Determination of the Mono and Diethanolamides of Palmitic Acid and of Soybean Oil Fatty Acids by High Performance Liquid Chromatography

Abstract

HPLC separations and quantitative analyses are described for palmitic and soya monoethanolamides and diethanolamides synthesized from free fatty acids, methyl esters and triglycerides. Both reverse phase and adsorption techniques were employed, using a differential refractometer for detection. Starting materials and crude reaction products are analyzed without treatment or preliminary separations. The methods described are simple and rapid and can be used to monitor the course of condensation reactions as well as final products compositions. In some instances separation of homologous fatty acid alkanolamides was achieved, enabling comparison of the yields obtained from individual fatty acid precursors.     

Neutral Lipids of Ruta graveolens L. Grown in vivo and in vitro

The composition of neutral lipids (NL) and fatty acids of acyl-containing components in differentiated tissues ofRuta graveolensL. (Rutaceae) grown in vivo and in vitro is studied. The NL of in vitro cultures differ from NL of the intact plant by a larger content of esters of fatty acids with alcohols, fewer high-molecular-weight alkanes, alkylbenzenes, free alkanols, and linolenic acid     

Determination of volatile fatty acid ethyl esters in raw spirits using solid phase microextraction and gas chromatography

An analytical method for the determination of fatty acid ethyl esters in raw spirits of different quality or produced from various raw materials has been developed and optimized. A combination of headspace solid phase microextraction (HS-SPME) as the extraction technique and gas chromatography with flame ionization detection (GC-FID) as the determination technique was utilized. HS-SPME conditions such as: type of the stationary phase of the fiber, ethanol content, sample volume, extraction temperature and time, salt addition and sample agitation were investigated to determine the most suitable conditions for the analysis of volatile fatty acid ethyl esters in raw spirits. The quantification method was an internal standardization using methyl octanoate as the internal standard. The method's detection limits (MDLs) for the individual ethyl esters ranged from 26.8 to 0.0470 μg L⁻¹ 20% EtOH. The feasibility of SPME for the quantitative analysis of fatty acid ethyl esters in raw spirits of different organoleptic quality was demonstrated. High precision and simple sample preparation enable the use of this method for routine investigations in both industrial and research laboratories.     

Measurement of free glycerol in biofuels

A method has been developed to determine the free glycerol content in esters derived from vegetable oils. After extraction of glycerol, its measurement in small quantities in biofuels (methyl or ethyl esters) is possible by high-pressure liquid chromatography combined with pulsed amperometric detection, HPLC-PAD. The method has proved to be simple, rapid and accurate. The limit of detection is 1 g/g.     

Measurement of oleic acid in human plasma by isotope dilution mass spectrometry

Summary A method for the quantitative determination of oleic acid in human plasma by isotope-dilution mass spectrometric technique is described. For the measurement of the fatty acid concentration (1-¹³C) oleic acid is added to the plasma sample. The fatty acids are extracted with n-hexane. Portions of the extract are esterified by the boron trifluoridemethanol method or stable isotope methylation. The methyl ester derivatives of the fatty acids are separated and detected by GC-MS with the mass spectrometer set to m/z 296 and 297. For the measurement of oleic acid after stable isotope methylation the m/z 299 and m/z 300 are monitored. The amounts of oleic acid in the plasma are calculated from the isotope ratios measured by selected ion monitoring. The recovery of the methylation step and the precision and accuracy of the GC-MS method are presented and discussed.