Pyrolysis-gass chromatography-mass spectrometry of soil humic fractions: II. The high boiling point compounds

4 pages, 1 figure, 1 table, 16 references.-- Publicado en el apartado: Division S-3-Soil Microbiology and Biochemistry.Pyrolysis-gas chromatography-mass spectrometry studies of soil fulvic and humic acids were made. The high boiling point compounds produced by pyrolysis were separated in a column packed with Chromosorb AW DMCS 80-100 mesh coated with 10% FFAP. Humic acids with a high nitrogen content yielded a complex variety of protein derivatives, such as alkylpyridines, alkylpyrroles, alkylbenzonitriles, indoles, piperidines, pyrazines, and pyrrolidones. Humic acids with low N content yielded a smaller number of heterocyclic nitrogen compounds. Lignin derivatives were also identified, but the amount varied in different samples. Furanes were not as prominent as protein and lignin fragments. Acid hydrolysis released proteins, polysaccharides, and lignins, which could be considered as companion materials of a humic "core". The majority of the pyrolysis compounds from the residue after hydrolysis were identified as alkylbenzenes, alkylnaphthalenes, phenols, benzofuranes, indenes, and fluorenes. Alkanes and alkenes were noted in trace amounts. Pyrolysis behavior of fulvic acids differed from that of humic acids. They produced poorly resolved pyrograms with smaller number and a lower intensity of peaks, from which only furfurals, phenols, benzofuranes, and naphthalenes could be identified.Peer reviewe

Procedimiento para la preparación de ésteres de hidroxitirosol, ésteres obtenidos y utilización

Procedimiento para la preparación de ésteres de hidroxitirosol, ésteres obtenidos y utilización. El objeto de la presente invención es un procedimiento para la preparación de una amplia gama de ésteres de hidroxitirosol. La síntesis de los compuestos se lleva a cabo por reacción de hidroxitirosol sintético o de los compuestos naturales hidroxitirosol, oleuropeína o aglucones de la oleuropeína (que se encuentran en el aceite de oliva, alpechín, orujo de oliva u hojas de olivo) con un agente acilante que es un compuesto que contiene al menos un grupo acílico de resto R, donde R es H, un radical alquilo de entre 1 y 21 átomos de carbono, sea lineal ó ramificado, un radical alquenilo de hasta 21 átomos de carbono ó un grupo arilo. Los ésteres preparados mediante el procedimiento de la invención pueden utilizarse como aditivo en productos alimenticios y cosméticos, así como en preparaciones farmaceúticas.Españ

Low boiling-point compounds produced by pyrolysis of fungal melanins and model phenolic polymers

Pyrolysis-gas chromatography-mass spectrometry was used to characterize fungal melanins and model phenolic polymers. Samples were pyrolysed at 700°C for 10 s and the low boiling-point compounds were separated on a Chromosorb 102 column. Low boiling-point compounds identified with a mass spectrometer coupled to the gas Chromatograph were very similar for peptone, a model autoxidative phenolic polymer incorporating peptone, and some fungal melanins. The major low boiling-point components from fungal melanins were related to proteins and to polysaccharides. A nitrogen-free phenolic polymer yielded very small amounts of low boiling-point pyrolysis fragments. The compounds identified appeared to be derived largely from the peptide, carbohydrate, and possibly small amounts of other aliphatic materials in the polymer structures.Peer Reviewe

Método mejorado para la determinación de triglicéridos en aceites de oliva mediante cromatografía líquida de alta eficacia

The analysis of triacylglycerols has great importance as quality control and origin determination aid in olive oils analytical methodologies. New improvements in the analysis of triacylglycerols by high-performance liquid chromatography in olive oils are developed in order to increase the separation between LLL/OLLn and OLL/OOLn critical pairs used for detection of seed oils in olive oils. Elution with acetone/acetonitrile (55:45) using gradient temperature and isothermal elution with propionitrile were investigated, in comparison with the European Union official method. The best resolution was achieved using propionitrile at 20ºC. Although the HPLC profile was similar using propionitrile and acetone/acetonitrile, differences in minor triacylglycerols contributing to each HPLC peak were encountered. The precision of the method was good.El análisis de triacilgliceroles tiene gran importancia como herramienta en el control de calidad y en la determinación del origen de los aceites de oliva. Nuevas mejoras en el análisis de triacilgliceroles en aceite de oliva mediante cromatografía líquida de alta eficacia se han desarrollado para mejorar la separación entre las parejas críticas LLL/OLLn y OLL/OOLn usadas en la detección de aceites de semilla en aceite de oliva. Eluciones con acetona/acetonitrilo (55:45) usando gradiente de temperatura y elución con propionitrilo en condiciones isotérmicas han sido investigadas en comparación con el método oficial de la Unión Europea. La mejor resolución se consiguió usando propionitrilo como eluyente a 20ºC. Aunque el perfil cromatográfico obtenido usando propionitrilo fue similar al obtenido usando acetona/acetonitrilo, se encontraron diferencias en los triacilgliceroles minoritarios que contribuyen a cada pico cromatográfico. La precisión del método fue buena.The authors wish to thank the European Commission for the financial support of the project (GRD1-2000-25011; MEDEO).Peer reviewe

Suggestions for the application of some analytical methods included in the regulation EEC 2568/91 relative to the characteristics of the olive oils and olive pomace oils

7 páginas, 8 figuras, 1 tabla.[ES] Entre los métodos analíticos aceptados oficialmente por la Unión Europea para su aplicación a los aceites de oliva y los aceites de orujo de oliva, las determinaciones de esteroles, trilinoleína, isómeros trans de los ácidos grasos y ceras han mostrado algunas dificultades en su aplicación. El estudio de dichos problemas ha permitido establecer diversas modificaciones y recomendaciones que facilitan la práctica de los métodos y mejoran la fiabilidad de los resultados.[EN] Among the analytical methods officially adopted by the European Union to be applied to olive oils and olive pomace oils, some troubles have been found in the application of the procedures for the determination of sterols, trilinolein, trans isomers of fatty acids and waxes. The study of such difficulties suggests several modifications and recommendations facilitating the performance of methods and improving the reliability of results.Los autores de este trabajo quieren hacer constar su más sincero agradecimiento a la CICYT por la financiación del proyecto ALI-91-0492.Peer reviewe

The determination of stigmastadienes in vegetable oils (Technical Report)

The development by collaborative study of a standardised method for the deter-mination of the stigmastadienes content in vegetable oils is described. The procedureinvolves the isolation of the unsaponifiable matter in the oil ands its fractioning on a silicagel column. The fraction containing the steroidal hydrocarbons is then analysed by capillarygas chromatography and the quantitative assessment made by the use of an internal standard/cholestan-3,5-stadiene. The procedure is very sensitive allowing determination at levels of0.01–4.0 mg/kg

Comparison between free radical scavenging capacity and oxidative stability of nut oils

Several works have measured free radical scavenging capacity of nut oils, since they may become a significant source of dietary fat. However, they have not considered kinetic parameters, what was the first aim of this work. Also, it was studied the possible relation between values of free radical scavenging capacity DPPH{radical dot} and oxidative stability (Rancimat method) in different nut (hazelnut, peanut, pistachio, walnut and almond) oils. The ranking of antioxidant capacity of nut oils, by both assays, was: pistachio > hazelnut > walnut > almond > peanut. A significant correlation was found between DPPH and Rancimat methods assays. Tocopherols appear to be the responsible compounds of this antioxidant capacity being neglictible the contribution of polyphenols. An interference effect of phospholipids, present in methanolic fraction of nut oils, was observed in the determination of polyphenols in nut oils by Folin and ortho-diphenols assays. © 2008 Elsevier Ltd. All rights reserved.The present research was performed under the financial support of the Spanish Ministry of Education and Science (Project AGL 2004-07579-C04-01/ALI)Peer Reviewe

Determinación de esteroles y dialcoholes triterpénicos en aceite de oliva mediante separación de la fracción por cromatografía líquida de alta eficacia y análisis por cromatografía de gases. Estandarización del método analítico.

A method is developed for the analysis of sterols together with triterpenic alcohols (erythrodiol and uvaol) in vegetable oils. The method involves obtention of the unsaponifiable matter, isocratic HPLC separation with refractive index detector, preparation of silylderivatives, and analysis by capillary GC. Four procedures involving GC analysis of sterol and sterol+dialcohol fractions obtained by HPLC and CCF separations are compared. A collaborative trial comparing HPLC-sterols+dialcohols and CCF-sterols (official) methods is carried out. For Δ7-sterols, higher values and better repeatability and reproducibility were observed in the first method, but no differences for the remainder sterols were found. The erythrodiol+uvaol determinations by HPLC-sterols+dialcohols and CCF-sterols+dialcohols (official) methods resulted in similar precision.<br><br>Se presenta un método para la determinación conjunta de esteróles y dialcoholes triterpénicos (eritrodiol y uvaol) en aceites de oliva que consta de las etapas siguientes: obtención del insaponificable, fraccionamiento mediante cromatografía líquida de alta eficacia (CLAE) en régimen isocrático con detector de índice de refracción, preparación de derivados sililados y análisis por cromatografía de gases en columna capilar. Se comparan cuatro procedimientos que utilizan el análisis por cromatografía de gases de las fracciones de esteroles y de esteroles + dialcoholes obtenidas tanto por CLAE como por CCF. Se lleva a cabo un análisis colaborativo para la determinación de esteroles comparando los métodos CLAE-esteroles+dialcoholes y CCFesteroles (método oficial). Los resultados mostraron que por el primer procedimiento la determinación de Δ7-esteroles se realiza con mayor repetibilidad y reproducibilidad, aunque los valores resultantes son más altos. No se encontraron diferencias en los parámetros de precisión ni en los valores de los restantes esteroles. Las determinaciones de eritrodiol+uvaol por los métodos CLAE-esteroles+dialcoholes y CCF-esteroles +dialcoholes (método oficial) resultaron con similar precisión

Determination of phospholipid fatty acid and triacylglycerol composition of rat caecal mucosa

The lipid composition of rat caecal mucosa, including the fatty acid composition of phospholipids and triacylglycerols, has been examined by capillary gas chromatography. Thirty-seven peaks were resolved, ranging in chain length from 12 to 24 carbon atoms. Preliminary identification of fatty acids by comparison with authentic standards was confirmed by gas chromatography—mass spectrometry using electron-impact ionization. The neutral and polar components were examined. Fatty acid methyl esters were quantified in absolute amounts with respect to the percentage of total phospholipid and triacylglycerols. The results show significantly higher levels of 16:0, 18:0, 18:1(n − 9), 18:1(n − 7), 18:2(n − 6) and 20:4(n − 6) in phospholipids, and higher levels of 16:0, 18:1(n − 9) and 18:2(n − 6) in triacylglycerols. On the other hand, analysis of caecal triacylglycerols revealed sn-glycerol-palmitate-oleate-palmitate, sn-glycerol-palmitate-linoleate-palmitate and sn-glycerol-palmitate-linoleate-oleate as major components