Fluorescent Labeling of Fatty Acids with 9-Anthryldiazomethane (ADAM) for High Performance Liquid Chromatography

Abstract

A novel method for rapid and simple fluorescent labeling of carboxylic acids with 9-anthryldiazomethane (ADAM) for HPLC is described. This reagent is stable in solution and highly reactive with carboxylic acids. Esterification proceeds at room temperature without catalyst. The labeled compounds are separated using a reversed-phase system and determined with a flow-through flurometer. Picomole level of fatty acids are determined by this method.     

GC/FTIR Potential for Structural Analysis of Marine Origin Complex Mixtures

Abstract

In this paper, we show the GC/FTIR contribution to the structural elucidation of marine origin complex mixtures. Three examples are given concerning aromatic hydrocarbons, fatty acid methyl esters and polychlorobiphenyls. These examples show the capability of GC/FTIR to differentiate isomers of aromatic hydrocarbons and polychlorobiphenyls and to rapidly characterize the different classes of fatty acid methyl esters (ramification, insaturation, cis/trans isomerism, hydroxyl group, cyclopropane ring).     

Development of High Pressure Liquid Chromatography (HPLC) for Fractionation and Fingerprinting of Petroporphyrin Mixtures

Abstract

A method is described which permits the analysis of fossil porphyrin mixtures by HPLC. This method involves the fractionation of the demetallated petroporphyrin mixtures on silica columns followed by rechromatography of the trapped fractions on ODS columns. This coupling of the two modes of HPLC provides a fast and effective method for the separation of isomeric porphyrins and for the petroporphyrin fingerprinting of geological (oil/shale) samples. Representative examples of analysis are discussed in terms of the potential applicability of the technique in the areas of structure elucidation and geochemical correlations.     

HPLC Phospholipid Separation Mechanisms on Silica,Amino, and Diol Columns

Abstract

The HPLC separation of phospholipid mixtures was investigated on silica, amino, and diol columns, using mobile phases consisting of acetonitrile, methanol, and phosphoric or trifluoroacetic acids in varying proportions. An explanation of the mechanism of these separations is given with regard to the individual column types.     

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.     

An Improved Technique for Extraction,Identification, and Quantification of Leukotrienes

Abstract

An improved method for extraction, separation and quantification of leukotrienes is described. Critical steps include extraction in thoroughly cleaned Sep-Pak C₁₈ mini columns, elution with 90 percent methanol in water, addition of 0.25 percent Na₄EDTA to the solvent system of methanol/water 60/40, pH 7.4, injection of the samples in 1 ml of the same system after lowering the pH to 3.0 with glacial acetic acid and utilization of a Z-module containing a 5 μm C₁₈ reverse phase cartridge. Recovery of the leukotrienes was 94 pm 8% mean pm SD for LTC₄, 89 pm 5% for LTD₄, 89 pm 3% for LTB₄ and 84 pm 6% for LTE₄. We had no problems with precipitation of Na₄EDTA and occlusion of the HPLC fittings. The method is simple, reproducible and easily adaptable to any research laboratory.     

Determination of Free Fatty Acids in Natural Oils and Alkyd Resins by High Performance Liquid Chromatography

Abstract

Mixtures of free fatty acids in natural oil and alkyd resin samples have been analyzed using a μBondapak Free Fatty Acid column in conjunction with a ternary mobile phase. Variation of the mobile phase composition allows ‘‘fingerprinting'’ as well as quantitation of the fatty acid components. Samples can be analyzed in ten minutes by this method. The results of the application of this technique to the identification of oil sources of fatty acids as well as the production of fatty acids during alkyd resin synthesis are given. Good agreement is observed for fatty acid compositions determined via HPLC with those obtained by gas chromatographic methyl ester analysis.     

Reversed-Phase,Ion-Pair Separation of L-Methionine and L-Methionine Dipeptides Complexed with Palladium (II)

Abstract

A high performance liquid chromatographic (HPLC) method is described for separation of L-methionine and L- methionine dipeptides complexed with palladium (II). Under isocratic conditions, at room temperatures, with the appropriate selection of counter-ion (cetyltrimethylammonium or trioctylmethylammonium), it was possible by ion-pairing reversed phase chromatography to resolve the palladium (II) complexes studied. Stainless steel and polythylene columns were used. The chroma-tograms from both the two different materials made columns indicate about the same ratio of capacity factor of the palladium (II) complexes.     

A Universal Standard for Direct Injection Hydrogen Enthalpimetry of Some Common Unsaturated Lipids

Abstract

The method of hydrogen enthalpimetry as previously applied to unsaturated and polyunsaturated lipids has employed an authentic sample of each lipid analyte for construction of the enthalpimetric calibration curve. This study shows that individual lipid standards are not necessary for several common naturally-occurring fatty acids, methyl esters and simple triglycerides, each of which can be expressed as equivalent mg of methyl oleate. Data are given for six lipids having from one to nine moles of double bonds per mole of analyte, i. e., from oleic acid to trilinolenin.     

Zur Synthese von 1-(3,3-Dimethyl-2-norbornyl)-äthanon

An improved synthesis of the title compound (1) is described. The catalytical action of variousLewis acids on the sterically hinderedDiels-Alder reaction of mesityl oxide with cyclopentadiene has been investigated. The mixture ofendo- andexo-isomers of the unsaturated intermediate2 yielded pure1 on hydrogenation and isomerization by sodium methoxide. The proof of theexo-configuration of the acetyl group has been achieved by mass spectra and 100 MHz¹H-NMR spectra.

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Herrn Prof. Dr.M. Pailer mit den besten Wünschen zum 65. Geburtstag gewidmet.     

Capillary GC Determination of Short-Chain Dicarboxylic Acids in Rain,Fog, and Mist

Abstract

A capillary GC and GC-MS method, employing dibutyl esters is described for determining short-chain dicarboxylic acids in rain, fog and mist samples collected in the Los Angeles area. Approximately twenty dicarboxylic acids (C₂-C₁₀) were identified in the water samples, including cis (maleic) and trans (fumaric) unsaturated, saturated, normal, branched and aromatic. Oxalic acid is the dominant acid, followed by succinic and malonic acids. The total concentrations measured are 2.9–51μM, 64–66 μM and 12 μM for rain, fog and mist samples, respectively. These diacids are probably produced by photooxidation of anthropogenic and possibly biogenic organic compounds in the atmosphere.     

Analysis of Taurine in Blood Plasma of Epileptic Patients Using an Improved Isocratic HPLC Method for Amino Acids

Abstract

An efficient, reversed-phase HPLC method is described in which 21 derivatized amino acids were isocratically separated in less than 90 minutes. An internal standard was used to improve precision and accuracy. The method, which separated taurine from α-, β-, and γ-aminobutyric acids, was used to quantify taurine levels in 83 blood plasma samples. A statistical comparison was made between taurine levels found in the plasma of epileptic and non-epileptic children.     

Recycling HPLC of p-Bromophenacyl Esters of Saturated C35–56 Fatty Acids from Mycobacterium Tuberculosis H37Ra on a Silica Column

Abstract

The p-bromophenacyl esters of saturated C_35–56 fatty acids from Mycobacterium tuberculosis H37Ra were separated according to structural classes on a silica column by high performance liquid chromatography (HPLC). The sample was cycled five times during HPLC. Highly purified C_35–38 esters were obtained by this method. Further HPLC fractionation on a reverse-phase column (C₁₈-bonded silica) gave complete separation of most of the remaining fractions. By combining mass spectrometry with HPLC separations, many of the fatty acid esters were tentatively identified.     

Synthesis and Application of 3,3-Spirocyclopropane Derivatives Obtained from 1,2:5,6-Di-O-Isopropylidene-α-D-Glucofuranose

Abstract

3,3-Spirocyclopropane derivatives (5 and 7) were prepared by three different methods of cyclopropanation starting from 1,2:5,6-di-O-isopropylidene-α-D-glucofuranose (2). Subsequent radical induced cyclopropane ring opening reaction stereo-specifically provided the 3-C-allyl derivative (9). However, activation of the cyclopropyl ring through the aldehyde (10) followed by hydrogenation gave a quaternary chiral derivative (11) which was elaborated to the versatile intermediate (1) by using Bamford-Stevens reaction.

     

High Resolution Separation of Urinary Organic Acids by High Performance Liquid Chromatography

Abstract

Reverse phase, anion exchange, and two-dimensional HPLC techniques were studied in order to increase resolution of organic urinary acids for eventual quantitative measurements. Reverse phase HPLC with a phosphate buffer/acetonitrile gradient yielded a separation of over 85 components in forty minutes and a peak area reproducibility of better than 5%. Connecting two reverse phase columns together resulted in the separation of 110 components. Anion exchange chromatography was determined to be of little use in resolving urinary acids in a resonable time except as the first stage in two-dimensional chromatography where fractions from the anion exchange column were injected into a reverse phase column. Over 139 components were separated by this two-dimensional method.     

Separation of Hydroxylated Metabolites of Fatty Acids (C10-C18) on a μPorasil Silica Column Using an Isocratic HPLC System

Abstract

A simple, versatile, and rapid normal-phase isocratic HLPC system is described for the analysis of the major (omega and omega-1) metabolites of C₁₀-C₁₈ chain length fatty acids formed upon incubation with rat liver microsomes and NADPH. Quantitation was achieved by radiometric detection. Chromatographic separation was performed by elution of the fatty acids and their omega and omega-1 metabolites from a 10μ silica column (μPorasil) with hexane:2-propanol:acetic acid (96.5:2.5:1.0). Retention times for these metabolites ranged from 10 to 13 minutes for stearic acid and from 16 to 21 minutes for capric acid. Recovery of the fatty acids and their metabolites from the column was greater than 95 percent. Relative quantitative conversion of the fatty acid substrates to omega and omega-1 metabolites was in the following order: myristic acid > capric acid=lauric acid=palmitic acid ? stearic acid. The omega products were formed preferentially over the omega-1 products of all the fatty acids except lauric acid. The method proved suitable for routine determination of NADPH-dependent fatty acid hydroxylase activities in rat liver microsomes.     

Cellular Fatty Acid Composition of Vibrio parahaemolyticus by Reversed-Phase High-Performance Liquid Chromatography

Abstract

High-performance liquid chromatography was used to separate and identify cellular fatty acids isolated from Vibrio parahaemolyticus, a gram-negative estuarine microorganism associated with seafood-borne enteritis in man. Fatty acids were isolated from statically grown bacterial cultures, saponified, and derivatized with an ultraviolet tag. Aliquots of derivatized fatty acids were injected onto a reversed-phase column with water:acetonitrile gradient as the mobile phase and ultraviolet detection at 254 nm. The predominant fatty acids found for the V. parahaemolyticus strains studied were C12, C14, C16:1, C16, C18:1, and C18. In addition, previously unreported fatty acids C13, C17, C19, and C21 were identified. Comparison of HPLC with GLC fatty acid separations showed good agreement with the exception that HPLC was able to resolve previously unidentified fatty acid constituents.     

On-line hydrogenation of fatty acid methyl esters in capillary gas chromatography

An injection splitter in front of a glass capillary column was used for the hydrogenation of fatty acid methyl esters (FAME) mixtures. Hydrogenation followed by gas chromatographic analysis on capillary columns permitted detection and identification in complicated natural mixtures of branched fatty acids, showing minor structural differences, in quantities down to 10^?8g. The technique described, apart from its suitability for FAME analysis, shows promise for structure determination studies of other classes of compounds.     

Über die Reaktion des (5α,9α,13β,14β)-3-Methoxy-17-methyl-9-sulfooxy-4,5-epoxyhasubanan-6-ons mit Alkalien

Treatment of the 9-sulfooxy-4,5-epoxy-hasubananone1 with alkali leads not only to the cyclopropane derivative3 but also to the new compounds4, 6 a, 9 and10. Structural assignments are based on IR and NMR spectral data and on chemical conversions. Some considerations on the mechanism of this reaction are described.

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Herrn Prof. Dr.M. Pailer mit den besten Wünschen zum 65. Geburtstag gewidmet.     

Enantiospecific synthesis of α-amino acid semialdehydes: a key step for the synthesis of unnatural unsaturated and saturated α-amino acids

The enantiospecific synthesis of unnatural unsaturated and saturated α-amino acids based on a Wittig type reaction is described. The versatile synthetic intermediates, l-glutamic and l-aspartic acid semialdehydes, are obtained from the corresponding N,N-di-Boc-diesters, by the selective reduction of the ω-ester with DIBAL^® under controlled conditions. The semialdehydes are chemically stable for a prolonged time and react with various phosphorous ylides, under controlled conditions, to produce the enantiomerically pure unsaturated α-amino acids in high yields. The method is equally applicable to homologated diesters obtained by the presented methodology providing unsaturated amino acids with variable unsaturated positions and geometries. The corresponding saturated products can be obtained by simple hydrogenation.