Chromatographic and spectroscopic investigation of the associative changes with the selected higher fatty alcohols

An attempt was made to compare usefulness of the ir spectroscopic technique with paper chromatography in the investigations concerning self-association of higher fatty alcohols. A conclusion was drawn that only the complementary application of both analytical methods better enabled to trace the establishing of association equilibria in the given experimental conditions.     

Investigation of the self association of higher fatty alcohols and acids on chromatographic sorbents

Summary Three different sorbents, one with high activity (silica gel), the second with medium activity (cellulose powder) and the third having low activity (chromatographic paper) were compared in respect of their usefulness for the evaluation of the self association of selected higher fatty alcohols and acids. The obtained results are correlated with IR spectroscopic data and theoretical considerations.     

Investigation of the association of higher fatty alcohols by means of paper chromatography

Paper chromatography investigations were performed with the aim of tracing the adsorption mechanism of the selected higher fatty alcohols on a paper layer and determining the role of polar solvents in establishing thermodynamic equilibria.     

Elucidation of the chromatographic behaviour of higher fatty alcohols and acids on cellulose sorbents

Summary An effort was undertaken to elucidate the chromatographic behaviour of higher fatty alcohols and acids on Whatman No. 2 paper. A model of the dipole association was assumed, aiming to simply describe the intermolecular interactions between a molecule of the chromatographed substance and the sorbent monolayer. The thermodynamic relationships correspond to the empirical relationships, established during the studies.     

HPLC of fatty acid esters of mono- and polyhydric alcohols. Part 2: Preparative separation

This paper demonstrates how simply and rapidly fatty acid esters of mono- and polyhydric alcohols can be separated quantitatively in preparative quantities on Lobar® RP-8 packed columns. After the separation of unknown mixtures, the isolated esters are identified from spectroscopic data (IR/NMR) and, after saponification of the ester components (fatty acids and alcohols), from the retention times of gas and high-pressure liquid chromatographic separations. Thus, in particular, sparingly volatile or nonvolatile partial esters of polyhydric alcohols, as well as the long-chained full esters, can be determined qualitatively and quantitatively. The following fatty acid esters of mono- and polyhydric alcohols have been separated: the i-propylesters of the laurinic and myristinic acids, the i-butyl-, i-octyl- and i-octadecyl-esters of the palmitinic and stearic acids, the mono- and di-fatty acid esters of the 1,3-bis-(2-hydroxyethyl)-5,5-dimethylhydantoins, the mono-, di- and tri-esters of the trimethylalpropane and the full esters of the pentaerythrite.     

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.     

Die gas-chromatographische Bestimmung von Fettalkoholen in Lanette N® und Lanette E®

Summary A simple gas chromatographic method for the quantitative determination of fatty alcohols in the emulsifying cetylstearylalcohol (Lanette N) and the sodium salt of cetylstearylsulphate (Lanette E) is described. Columns packed with 2.5% diethyleneglycol succinate on Chromosorb G and 10% EGSS-X on Gas-Chrom P achieved good separations and satisfactory results which are tabulated.      

Quality assurance of commercial beeswax II. Gas chromatography-electron impact ionization mass spectrometry of alcohols and acids

Gas chromatography with mass spectrometric detection was used to find the fraction of alcohols and acids present in pure beeswax from Apis mellifera. Some new compounds not described till now were found, such as a family of unsaturated linear fatty acids, several hydroxyacids and 1,2,3-propanetriol monoesters. The chromatographic profiles obtained from pure beeswax and bee-rejected foundation beeswax can be used to discriminate them; they mainly differ in the amount of some acids and alcohols.     

Trace analysis of surfactants derived from fatty alcohols I. Optimization of derivatization reaction

Summary Pre-column derivatization of the primary hydroxyl group in fatty alcohols and fatty alcohol ethoxylates using carbazole-9-carbonyl chloride (CC−Cl) and FMOC-Cl is described and compared with derivatization with 1-naphthoyl chloride (N−Cl). As the excess of derivatization reagent leads to a broad and strongly tailing reagent peak, it hinders trace determination of fatty alcohols and fatty alcohol ethoxylates. Therefore, an off-line as well as an on-line solid-phase extraction (SPE) method for removal of excess reagent are described. The on-line method which is based on column switching, shows better reproducibility higher pre-concentration, lower risk of contamination and can be easily automated, while the off-line method is better suited for the analysis of derivatized, fatty alcohol ethoxylates. An example of the trace analysis of fatty alcohols with a concentration of 2 ppb is given.     

光酶级联一锅法合成手性脂肪胺

对映体脂肪胺在有机合成与化工领域具有广泛的应用, 但其主要依赖于金属催化获得. 我们设计了一种光催化与酶催化级联催化的合成方法, 由脂肪醇出发合成手性脂肪胺. 通过筛选, 发现9-芴酮在可见光激发下可高效催化脂肪醇氧化为脂肪酮, 后者作为反应中间体被转氨酶在胺供体存在下经转氨反应合成手性胺. 在一锅法条件下, 该级联方法转化率可达99%, 目标产物的光学纯度>99%. 此外, 该光催化体系可分别与手性互补的转氨酶级联, 进而获得手性反转的脂肪胺产物. 该光酶级联催化方法充分结合了光催化的高效率与酶催化的立体选择性优势, 为手性脂肪胺类分子的合成提供了一种新型合成方法.     

Analysis of tissue free fatty acids isolated by aminopropyl bonded-phase columns

Gas chromatographic analysis revealed that polyunsaturated fatty acids such as arachidonic acid and total tissue free fatty acids isolated from an aminopropyl bonded-phase column yield a two- to three-fold higher recovery of arachidonic acid as compared to those isolated from thin-layer chromatographic plates. This method was further improved by packing the aminopropyl bonded phase in glass columns, since the glass column significantly eliminated the other contaminants (from polypropylene columns) coeluting with fatty acids in both a neutral lipid thin-layer chromatographic system and on a 5% DEGS-PS column of gas chromatographic analysis. In aminopropyl bonded-phase columns, the standard triglycerides and phospholipids were completely separated from free fatty acids as judged by gas chromatographic analysis. These results warrant the use of an aminopropyl bonded-phase column for the isolation of free fatty acids to obtain better recovery of polyunsaturated fatty acids.     

Analysis of alcohols, as dimethylglycine esters, by electrospray ionization tandem mass spectrometry

Dimethylglycine (DMG) esters are new derivatives for the rapid, sensitive and selective analysis of primary and secondary alcohols, in complex mixtures, by electrospray ionization tandem mass spectrometry (ESI-MS/MS). Their development was inspired by the use of the complementary dimethylaminoethyl esters for the trace, rapid analysis of fatty acids. DMG esters are simply prepared by heating a dichloromethane solution of the imidazolide of dimethylglycine, containing triethylamine, and an alcohol. DMG esters of long-chain fatty alcohols, isoprenoidal alcohols and hydroxy-acids are analysed by electrospray ionization tandem mass spectrometry with a precursor ion of m/z 104 scan. Diols, glyceryl esters, glyceryl ethers and some sterols are analysed by a neutral loss of 103 Da scan. Trimethylglycine (TMG) ester iodides, prepared by alkylation of DMG esters with methyl iodide, are more sensitive derivatives for molecules containing secondary alcohol groups, such as cholesterol and gibberellic acid. They are analysed by a precursor ion of m/z 118 scan. DMG or TMG derivatives were shown to be at least comparable and sometimes an order of magnitude more sensitive than N-methylpyridyl ether derivatives for ESI-MS/MS analysis of the different classes of alcohols. Applications of these derivatives for the diagnosis of inherited disorders and the analysis of natural products are presented.     

Fast identification of mycobacterium species by GC analysis with trimethylsulfonium hydroxide (TMSH) for transesterification

Trimethylsulfonium hydroxide (TMSH) reproducibly converts fatty acids bound in, e.g., biomolecules such as phospholipids and/or glycerides, into the corresponding fatty acid methyl esters (FAMEs). The transesterification can be performed at room temperature in a fast single step reaction. Surprisingly, secondary alcohols and mycolic acid cleavage products (MACPs) are also released from mycobacteria under these conditions. The complex reaction mixtures containing FAMEs, MACPs, and secondary alcohols can easily be separated by high resolution temperature-programmed capillary GC. Different species of mycobacteria give rise to characteristic chromatographic patterns and the amount of lipids from a single colony of mycobacteria is sufficient for reliable identification of the bacteria. The profiles of the chromatograms match well those obtained from other sample preparation techniques. The TMSH method of identification of mycobacteria from the patterns of the gas chromatograms is faster and more sensitive than conventional methods, which also involve transesterification. The identification of mycobacterial species by microbiological culture techniques is difficult to perform and requires several weeks.     

气相色谱法测定洗涤剂用脂肪醇

建立了一种快速、准确测定洗涤剂用脂肪醇的气相色谱分析方法。采用气相色谱和质谱联机方法对洗涤剂用脂肪醇进行了定性分析,采用气相色谱法对洗涤剂用脂肪醇进行了定量分析。用正构脂肪醇对定量分析方法进行了考察,其结果的相对标准误差为2．2％。用气相色谱确定了每个组分的含量,定量结果的相对标准偏差小于2．6％。分析结果为装置操作优化及改进洗涤剂脂肪醇的正构度提供了技术支持。     

用Benson基团加和法预测气相色谱保留值

应用Ｂａｎｓｏｎ基团加和法，对氯代苯，脂肪醇两类化合物分子结构与气相色谱保留值间的关系进行了研究。对部分化合物的保留值做了预测，结果表明这两类化合敢相色谱保留值具有基团加和性，预测值与实验值吻合很好。     

CO+H_2合成低碳醇的毛细管色谱分析

CO+H_2合成低碳醇是由煤制取液体燃料和化工原料的主要途径之一。随催化剂不同,可以合成以甲醇和异丁醇为主,用作汽油掺合剂的低碳燃料醇,也可得到以正构醇为主,用以生产化工原料用的醇类的低碳化学醇。这两种合成醇中异构体多,水份多,因此用填充柱分离,常有一定困难。1987年徐淑英用OV-101毛细管柱对     

Comparative estimation of the efficiency of structure formation and dispersion interactions in organic solvents of varying nature and polarity

The solubilities of n-tetracosane and dotriacontane in more than 50 solvents (aliphatic and aromatic hydrocarbons, their halo derivatives, alcohols, ethers, ketones, amines, etc.) miscible with liquid aliphatic hydrocarbons were determined at 293±1 K. The increments of the methylene group in hypothetical extraction systems n-octane — solvent and the free energies of methylene group transfer from solvent to n-octane were calculated. The values were found to vary within wide limits. For the overwhelming majority of polar and low-polar solvents, the energies are negative due to self-association of solvents according to the type of spatial structure. Positive energies are due to the closer packing of some low-polar solvent molecules (carbon tetrachloride and cyclohexane) in the structure compared to octane and to the absence of molecular self-association. The closer packing of these molecules leads to higher efficiency of dispersion interactions between the solvents and paraffins compared to octane.     

Gas chromatographic determination of high molecular weight alcohols from policosanol in omega-3 fish oil by acylation with acetyl chloride

A new validated gas chromatographic (GC) method using acetyl chloride as a derivatizing agent for determining policosanol's high molecular weight alcohols (policosanol's fatty alcohols; PFAs) in fish oil (FO) is described. Before derivatizing the alcohols, FO was subjected to a methylation reaction, and then the PFAs were isolated in a chloroform fraction by silica gel by column liquid chromatography. GC analysis was performed using a BPX-5 wide-bore column and 1-eicosanol as an internal standard. Validation assays applied to the method proved noninterference by a very complex mixture of the FO with PFAs, even for samples subjected to stress conditions. Good linearity [correlation coefficient >0.999, relative standard deviation (RSD) of the slope <1.3%, and RSD of the response factors <1.9% with no bias] and accuracy (average recovery from 100.6 to 102.2%) over a range of 28-142% of the nominal concentration were obtained. Within-day and intermediate precisions at the nominal dose (100%) were 1.7 and 2.9%, respectively. The method was successfully used to identify and quantitate the PFAs in FO.     

The mechanism of chemical modification of artificial fibers based on cellulose derivatives

A fabric based on cellulose derivatives has been hydrophobized via coating with oligochloromethylethoxysiloxane and then treated with butyl alcohol, benzyl alcohol, and higher fatty alcohols. With the use of X-ray photoelectron spectroscopy, it has been shown that the reaction of alcohols with the siloxane coating proceeds through the exchange of ethoxysilane groups for higher alkoxy groups, whereas the expected reaction of chloromethyl groups with alcohols (the Williamson reaction) does not occur under the chosen conditions.     

Investigation of the possible role of fatty acids and alcohols as precursors of normal hydrocarbons generated during vacuum pyrolysis of a young kerogen

Significant amounts of fatty acids and alcohols, in addition to straight-chain hydrocarbons, were observed in the vacuum pyrolysate of a young kerogen isolated from a fresh-water sediment. The amounts and the distribution patterns of fatty acids and alcohols were compared with those indigenous to the original kerogen, as determined by solvent extraction followed by saponification extraction. Straight-chain fatty acids in the pyrolysate were 12.7 mg/g kerogen, while those extracted from the original kerogen were 10.5 mg/g. The amounts of fatty alcohols in the pyrolysate and in the extracts were 1.31 and 1.10 mg/g. respectively. The excess amounts in the pyrolysate were explained by the release of a strictly bound form of fatty acids and alcohols, which were left in the kerogen matrix even after the saponification extraction. The results indicated that most fatty acids and alcohols were not decomposed as a result of the vacuum pyrolysis and that neither fatty acids nor fatty alcohols should be viewed as the prime precursors of the straigth-chain hydrocarbons (4.6 mg/g) simultaneously generated during vacuum pyrolysis.