Gas chromatography and silver-ion high-performance liquid chromatography analysis of conjugated linoleic acid isomers in free fatty acid form using sulphuric acid in methanol as catalyst. 2008

Pilar Luna, and Manuela Juárez, and Miguel Angel de la Fuente
Instituto del Frío, Consejo Superior de Investigaciones, José Antonio Novais 10, Madrid, Spain.

This study used GC and silver-ion HPLC to examine the effects of temperature and time on methylation of individual and mixtures of conjugated linoleic acid (CLA) isomers in free fatty acid form using sulphuric acid as catalyst. In the conditions tested (temperatures between 20 and 50 degrees C and times between 10 and 60 min) methylation was complete while avoiding isomerization of conjugated dienes and the formation of artefacts that could interfere with chromatographic determinations. An analytical method using solvent extraction of the lipids followed by selective elution of the free fatty acids from aminopropyl bonded phase columns and methylation with H(2)SO(4) in mild conditions was then applied to determine the CLA isomers in free fatty acid form in rumen fluid, and the results were evaluated.

UI MeSH Term Description Entries
D007536 Isomerism The phenomenon whereby certain chemical compounds have structures that are different although the compounds possess the same elemental composition. (From McGraw-Hill Dictionary of Scientific and Technical Terms, 5th ed) Isomerisms
D008745 Methylation Addition of methyl groups. In histo-chemistry methylation is used to esterify carboxyl groups and remove sulfate groups by treating tissue sections with hot methanol in the presence of hydrochloric acid. (From Stedman, 25th ed) Methylations
D002384 Catalysis The facilitation of a chemical reaction by material (catalyst) that is not consumed by the reaction. Catalyses
D002849 Chromatography, Gas Fractionation of a vaporized sample as a consequence of partition between a mobile gaseous phase and a stationary phase held in a column. Two types are gas-solid chromatography, where the fixed phase is a solid, and gas-liquid, in which the stationary phase is a nonvolatile liquid supported on an inert solid matrix. Chromatography, Gas-Liquid,Gas Chromatography,Chromatographies, Gas,Chromatographies, Gas-Liquid,Chromatography, Gas Liquid,Gas Chromatographies,Gas-Liquid Chromatographies,Gas-Liquid Chromatography
D002851 Chromatography, High Pressure Liquid Liquid chromatographic techniques which feature high inlet pressures, high sensitivity, and high speed. Chromatography, High Performance Liquid,Chromatography, High Speed Liquid,Chromatography, Liquid, High Pressure,HPLC,High Performance Liquid Chromatography,High-Performance Liquid Chromatography,UPLC,Ultra Performance Liquid Chromatography,Chromatography, High-Performance Liquid,High-Performance Liquid Chromatographies,Liquid Chromatography, High-Performance
D005230 Fatty Acids, Nonesterified FATTY ACIDS found in the plasma that are complexed with SERUM ALBUMIN for transport. These fatty acids are not in glycerol ester form. Fatty Acids, Free,Free Fatty Acid,Free Fatty Acids,NEFA,Acid, Free Fatty,Acids, Free Fatty,Acids, Nonesterified Fatty,Fatty Acid, Free,Nonesterified Fatty Acids
D000432 Methanol A colorless, flammable liquid used in the manufacture of FORMALDEHYDE and ACETIC ACID, in chemical synthesis, antifreeze, and as a solvent. Ingestion of methanol is toxic and may cause blindness. Alcohol, Methyl,Carbinol,Sodium Methoxide,Wood Alcohol,Alcohol, Wood,Methoxide, Sodium,Methyl Alcohol
D013464 Sulfuric Acids Inorganic and organic derivatives of sulfuric acid (H2SO4). The salts and esters of sulfuric acid are known as SULFATES and SULFURIC ACID ESTERS respectively. Acids, Sulfuric
D019787 Linoleic Acid A doubly unsaturated fatty acid, occurring widely in plant glycosides. It is an essential fatty acid in mammalian nutrition and is used in the biosynthesis of prostaglandins and cell membranes. (From Stedman, 26th ed) 9,12-Octadecadienoic Acid,Linoleate,9-trans,12-trans-Octadecadienoic Acid,Linoelaidic Acid,Linoelaidic Acid, (E,Z)-Isomer,Linoleic Acid, (E,E)-Isomer,Linoleic Acid, (Z,E)-Isomer,Linoleic Acid, (Z,Z)-Isomer,Linoleic Acid, (Z,Z)-Isomer, 14C-Labeled,Linoleic Acid, Ammonium Salt, (Z,Z)-Isomer,Linoleic Acid, Calcium Salt, (Z,Z)-Isomer,Linoleic Acid, Potassium Salt, (Z,Z)-Isomer,Linoleic Acid, Sodium Salt, (E,E)-Isomer,Linoleic Acid, Sodium Salt, (Z,Z)-Isomer,Linolelaidic Acid,cis,cis-9,12-Octadecadienoic Acid,trans,trans-9,12-Octadecadienoic Acid,9 trans,12 trans Octadecadienoic Acid,9,12 Octadecadienoic Acid,Acid, 9,12-Octadecadienoic

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