Thermal induction of 9t12t linoleic acid: A new pathway for the formation of Conjugated Linoleic Acids

Thermal induction of 9t12t fatty acid leading to the formation of Conjugated Linoleic Acids (CLA) has been demonstrated by subjecting glyceride, and methyl ester of the acid to heat treatment. Fifteen micro liter portions of the glyceride sample containing 9t12t fatty acid (trilinoelaidin) were placed in micro glass ampoules and sealed under nitrogen and then subjected to thermal treatment at 250oC. The glass ampoules were taken out at regular time intervals, and the contents were subjected to composition analysis by gas chromatography. The samples from each ampoule were subjected to derivatisation into their methyl esters. The methyl esters of the isomerised fatty acids were analysed by gas chromatography. The same procedure was repeated with methyl ester samples containing 9t12t fatty acid (methyl linoelaidate). The gas chromatographic analysis was carried out after appropriate dilution in heptane. The results show that the thermal induction of 9t12t fatty acids from both glyceride molecules and methyl esters give identical Conjugated Linoleic Acid (CLA) profiles. These profiles are identical to the profile obtained by the thermal induction of 9c12c fatty acid

The Fate of Phthalates in Surface Waters During Humus Removal by Precipitation

Phthalates are esters of aromatic 1,2 di-carboxylic acids and are widely found in surface waters and their removal is necessary because of their effects on human health. Humic material in water can adsorb phthalates and may be precipitated along with phthalates. The fate of phthalates in surface waters during humus removal by precipitation has been investigated in the laboratory with well characterised humic substances from the ?NOM typing project? (Natural Organic Matter typing project from Norway). Water samples have been prepared with humus samples from the project to mimic natural surface waters and a mixture of phthalates containing di-methyl, di-ethyl, di-propyl, di-butyl and di- (2-ethyl) hexyl phthalates (DEHP) were added to the water samples. After a week standing the humic material in the samples was precipitated by alum flocculation. After filteration, the remaining water was analysed for phthalates using solid phase extraction and Gas Chromatography.The results show that all the phthalates except DEHP were removed together with humic material in water. The concentration of DEHP can still exceed the allowed limit for phthalates and alternative techniques are needed to remove DEHP before the water is free from phthalates for human consumption

Water Chemistry in the Confluence Zone Downstream a Limestone Treated Lake and an Acid Tributary: Principal Component Analyses Including Warm and Cold Winters and an Episode High in Sea-Salts

Extensive limestone treatment of lakes and watercourses has been carried out especially in Norway and Sweden to counteract effects of acidification. Lakes have been the most commonly treated part of the water systems. However, treatment of lakes upstream acid tributaries may introduce downstream toxic mixing zones for fish. To sort this out the outlet of a treated lake, a downstream acid tributary and two sites in the confluence zone were intensely monitored during a period of 28 months. The data accumulated come from a period (from February 1992) where significant climatic variations took place that provide a basis for studying intercorrelations between water chemistry and climatic change. The first two winters were warmer than normal and the catchments were hardly covered with snow and the lake was ice-covered only for a few days. The last winter was colder than normal, nival and the lake was ice-covered from December to April. During the second winter a low pressure over the north Atlantic gave strong south-westerly winds and large amounts of precipitation loaded with sea-salts. The principal component analysis (PCA) separates both the outlet and the tributary data into two groups while the data from the confluence zone are separated into three. Significant different water chemistry was observed in the outlet during the ice-covered period while effects of the sea-salt event splits the data from the tributary into two groups. The water chemistry in the confluence zone reflects both the ice-covered period, the sea-salt event and besides the more general situation. The PCA analysis indicates that the changing weather conditions mainly influenced on the water quality in the tributary. The water quality in the confluence zone was generally a conservative mixture of the outlet and the tributary waters except for alkalinity, H+ and inorganic aluminium (Ali). Generally, hydrolysing Ali in the confluence rendered the water quality highly toxic to fish. The potential toxicity increased during the sea-salt event and during the ice-covered period of the lake due to increased concentrations of Ali both in the outlet and the tributary waters. The results indicate that this may be a general problem in confluence zones downstream limestone treated lakes and acid tributaries

Near infrared spectroscopic characterisation of surface hydroxyl groups on hydrothermally treated silica gel

Published version of an article in the journal International Journal of Chemical and Environmental Engeineering, 2 (1), 27-32. Also available at: http://www.warponline.org/4.%20Near%20infrared%20spectroscopic%20characterisation%20of%20surface%20hydroxyl%20groups%20on%20hydrothermally%20treated%20silica%20gel.pdf OASurface hydroxyl groups on hydrothermally treated silica gel have been under discussion several decades back with contradictory conclusions. Some authors meant that the hydrothermally treated sila gel increases the concentration of hydrogen bonded silanol groups on the surface and some concluded that the hyrothermal treatment increases the concentration of internal hydrogen bonded silanol groups. The contradictory stand points arose because of the difficulty in finding a technique that could give evidence for the presence of surface hydrogen bonded silanol groups.Recent investigation into the surface functionalities and adsorption evolution of water on silica gel surface by second derivative near infrared spectroscopy has provided spectroscopic evidence for the presence of surface hydrogen bonded silanol groups. The technique was employed to probe the surface of the hydrothermally treated silica gel samples. Two silica gel samples of varying surface characteristics have been used in this study. The samples were hydrothermally treated and their surface functionalities were probed using near infrared spectroscopy with second derivative approach.The results clearly indicate that the hydrothermal treatment of silica gel primarily increases the concentration of hydrogen bonded silanol groups on the silica gel surface. This happens because of the chemical transformation of the siloxane groups into silanol groups. These new silanol groups increase the chance for hydrogen bondings with neighboring silanol groups. Therefore, the concentration of free silanol groups decreases with the hydrothermal treatment. The adsorption of water takes place at the vicinal OH groups first and spreads over the surface by forming hydrogen bondings and ends with bonding at free silanol OH groups.A balanced concentration proportionality between free silanol groups and vicinal OH groups (arising from the hydrogen bondings between two or more of the neighboring silanol groups) is necessary for effective adsorption of water molecules on silica gel surface. A high proportion of the hydrogen bondings on the silica gel surface increase the concentration of vicinal OH and therefore the adsorption effectiveness of the sample decreases markedly

Evidence in the formation of conjugated linoleic acids from thermally induced 9t12t linoleic acid: a study by gas chromatography and infrared spectroscopy

Accepted version of article published in the journal: Chemistry and Physics of Lipids. Published version available on Science Direct: http://dx.doi.org/10.1016/j.chemphyslip.2009.07.002Thermally induced isomerisation leading to the formation of conjugated linoleic acids (CLAs) has been observed for the first time during the thermal treatment of 9t12t fatty acid triacylglycerol, and methyl ester. Fifteen microlitre portions of the triacylglycerol sample containing 9t12t fatty acid (trilinoelaidin) were placed in micro glass ampoules and sealed under nitrogen, then subjected to thermal treatment at 250 degrees C. The glass ampoules were removed at regular time intervals, cut open, and the contents were analysed by infrared spectroscopy using a single reflectance attenuated total internal reflectance crystal accessory. The samples were then subjected to derivatisation into their methyl esters. The methyl esters of the isomerised fatty acids were analysed by gas chromatography. The same procedure was repeated with methyl ester samples containing 9t12t fatty acid (methyl linoelaidate). Each sample was subjected to infrared measurements and gas chromatographic analysis after appropriate dilution in heptane. The results show that the thermally induced isomerisation of 9t12t fatty acids from both triacylglycerol molecules and methyl esters give identical CIA profiles as those found for the thermally induced isomerisation of 9c12c fatty acids. The infrared spectrometry provides additional evidence confirming the formation of CIA acids during thermal treatment. A mechanism for the formation of the CLAs from 9t12t fatty acid molecules is also formulated for the first time. This mechanism complements the pathways of formation of CLAs from 9c12c fatty acids during thermal treatment. (C) 2009 Elsevier Ireland Ltd. All rights reserved

Thermally Induced Isomerisation Kinetics of the 9c11t and 10t12c Conjugated Linoleic Acids in Triacylglycerols as Studied by FT-IR Spectrometry Aided by Gas Chromatography

Published version of an article from the journal:The Open Spectroscopy Journa. Also available from the publisher:http://dx.doi.org/10.2174/1874383801004010041. Open AccessIsomerisation kinetics of the 9c11t and 10t12c Conjugated Linoleic Acids (CLA) in triaclglycerols at isothermal conditions (250, 280 and 325oC) has been studied by infrared spectroscopy. Fifteen micro liter portions of the glycerides were placed in micro glass ampoules and sealed under nitrogen. Several glass tubes containing the same triacylglycerols were then subjected to thermal treatment. The glass tubes were removed at regular time intervals, cut open, and a part of the contents in each glass tube analysed by infrared spectroscopy using a single reflectance attenuated total internal reflectance crystal accessory. Then the rest of the products in each of the glass tubes were analysed by gas chromatography after derivatisation. The gas chromatographic results show that the 9t11c and 10t12c CLA isomers undergo a quick [1,5] sigmatropic transformations and form 8c10t and 11c13t respectively. These then form more stable 8t10t, 9t11t and 10t12t, 11t13t isomers respectively. Formation of the other CLA isomers is in relatively small quantities for shorter thermal induction times. The chromatographic profiles also show that the thermal induction reaction can be considered as a reaction starting from the pair of isomers formed through the [1.5] sigmatropic rearrangements. The intensity of one of the characteristic absorptions at 944 cm-1 arising from the out-of-plane =C-H deformation in the CLAs was used as the quantitative measure of the remaining triaclglycerol in the heated samples. The activation energies determined for the isomerisation reactions are 25.500.30 and 25.250.70 kcal/mol for the triacylglycerols containing 9c11t (8t10c) and 10t12c (11c13t) fatty acid isomers respectively

The nature of rest silanol groups on the surfaces of silica based solid phase extraction materials

Author's version of an article in the journal: Advanced Materials Research. Also available from the publisher at: http://dx.doi.org/10.4028/www.scientific.net/AMR.650.66Chemically bonded solid phase materials are very important in separation chemistry. The chemically modified silica gel contains rest silanol groups that can affect the retention properties when they are used for separation of compounds. Some commercially available solid phase extraction (SPE) materials based on silica gel were analysed for rest silanol groups by near infrared spectroscopy. The combination frequency of the water molecules in the 5500- 5000 cm -1 region was used in identifying the nature of water molecules on the surface and the information was used to identify the types of silanol groups on the surface. Second derivative technique was employed in the detailed analysis. Nine different SPE materials including C18, C8, C6H5, NH2, OH, CN, SiOH, SA (SCX) and SB (SAX) were examined by near infrared spectroscopy for rest silanol groups. The results show that the non-polar and polar stationary phases contain vicinal silanol groups and the ion exchange solid phase materials contain free, vicinal and geminal silanol groups

Near infrared spectroscopic study on the adsorption of methanol on silica gel

Author's version of an article in the journal: Advanced Materials Research. Also available from the publisher at: http://dx.doi.org/10.4028/www.scientific.net/AMR.650.150The silanol groups on Silica gel surface are sites for adsorption of polar molecules. Alcohols and other polar molecules are easily adsorbed by forming hydrogen bondings with OH groups on silica gel surface. A study on the adsorption of methanol on silica gel was carried out by using NIR spectroscopy in combination with ssecond derivative techniques. Four of the well characterised silica gel samples were used in this study. Each of the silica gel (0.25g) samples with different surface areas and silanol number was pressed into a small disc, placed in a glass vial and the physically adsorbed water molecules from the surface of the silica gel particles were removed by heating the sample to 200 °C under vacuum. The near infrared spectra of the cooled sample was recorded by a Perkin Elmer spectrum one NIR spectrometer equipped with a transflectance accessory and a deuterated triglycine detector at a resolution of 16 cm-1. The glass vial was then opened and a tiny tube filled with methanol was inserted in the glass vial. Then the near infrared spectra of the sample during the adsorption of methanol were recorded at regular time intervals until there is no apparent change in the spectra. The second derivative profiles of the spectra were obtained using the instruments' software. The mass of the silica gel pellet was determined by an analytical balance and the methanol adsorbed on the surface was calculated. The number of methanol layers on the silica gel surface was calculated using the silica gel particle characteristics of the samples. The results show that the adsorption evolution of methanol progresses on the samples and the surface was covered by a mono layer within the first 60 minutes. Furthermore, it appears that the adsorption of multilayer on methanol starts after all the surface silanol groups are exhausted

Thermal induction of 9t12t linoleic acid: A new pathway for the formation of Conjugated Linoleic Acids

Accepted version of an article published in the journal: International Journal of Engineering and Technology Published version available at: http://www.ijetch.org/papers/066.pdfThermal induction of 9t12t fatty acid leading to the formation of Conjugated Linoleic Acids (CLA) has been demonstrated by subjecting glyceride, and methyl ester of the acid to heat treatment. Fifteen micro liter portions of the glyceride sample containing 9t12t fatty acid (trilinoelaidin) were placed in micro glass ampoules and sealed under nitrogen and then subjected to thermal treatment at 250oC. The glass ampoules were taken out at regular time intervals, and the contents were subjected to composition analysis by gas chromatography. The samples from each ampoule were subjected to derivatisation into their methyl esters. The methyl esters of the isomerised fatty acids were analysed by gas chromatography. The same procedure was repeated with methyl ester samples containing 9t12t fatty acid (methyl linoelaidate). The gas chromatographic analysis was carried out after appropriate dilution in heptane. The results show that the thermal induction of 9t12t fatty acids from both glyceride molecules and methyl esters give identical Conjugated Linoleic Acid (CLA) profiles. These profiles are identical to the profile obtained by the thermal induction of 9c12c fatty acid