Zum täglichen Verzehr trans-isomerer Fettsäuren Eine Kalkulation unter Zugrundelegung der Zusammensetzung handelsüblicher Fette und verschiedener menschlicher Depotfette

Daily Consumption of trans-Isomeric Fatty Acids - A Calculation Based on Composition of Commercial Fats and of Various Human Depot Fats When highly efficient and selective packed columns (Silar 10C, SP 2340) are used in the gas chromatographic analysis of cis/trans-isomeric fatty acids present in partially hydrogenated fats for human consumption, the measurements of the relative trans-octadecenate content are regularly too low by several percent in favor of the respective cis-octadecenate fraction. This methodological error is due to the fact that the heterogeneity of the trans-component is greater than that of the cis-fraction with regard to the positional isomers present. It is assumed that the ingestion of trans-octadecenate with food averages 4.5 g to 6.4 g per capita and day in Western Germany. This assumption is based on individual fatty acid analyses performed on a total of 110 different brands of fat purchased in 1973/74 and again in 1976, on the individual market share of these fats, and on the average consumption of fat including ruminant products. Approximately 35% to 45% of the above amount are taken up with ruminant products, the main part results from the ingestion of partially hardened fats. The value determined for the ingestion of trans-fatty acids correlates relatively well with a mean trans-octadecenate content of 2% (1.0-4.3%) measured post mortem in the subcutaneous, mesenterial, perirenal and subepicardial adipose tissue of 16 males of normal weight.     

The OV 275-packed stainless steel column intrans-fatty acid research: A note of caution

Gas chromatographic analysis of fatty acid methyl esters in a 6.1 m stainless steel column packed with 15% OV 275 and operated at 220 C resulted in poor recovery of polyunsaturated esters relative to their saturated or monoenoic counterparts. Relative responses of the esters declined with increasing unsaturation, were concentration-dependent at low concentrations and changed as the column aged. Decomposition of polyunsaturated compounds in the hot stainless steel column appeared to be the major reason for their poor recovery and renders this particular column of doubtful value in analysis of complex ester mixtures.     

Gas chromatographic equivalent chain lengths of fatty acid methyl esters on a silar 10C glass capillary column

Gas chromatographic equivalent chain lengths have been determined for a number of fatty acid methyl ester isomers on a Silar 10C glass capillary column at 170 C. The results are comparable with others published for polycyanopropylsiloxane columns.     

Quantitation of fatty acids from flue-cured tobacco by combined preparative thin layer chromatography-gas chromatography

Flue-cured tobacco was subjected to alkaline hydrolysis, and, after acidification, the fatty acids and nonsaponifiables were extracted into hexane. Treatment of the hexane extract with diazomethane yielded fatty acid methyl esters. The methyl esters were separated from interfering hydrocarbons and sterols by preparative thin layer chromatography (PTLC). After addition of an internal standard, the esters were quantitated by gas chromatography on the column packing, Silar 10C. Quantitation of the C₁₄-C₃₂ fatty acid esters was possible by means of temperature programming.     

Einfluß von Licht und Tocopherolgehalt auf die Oxidationsstabilität von Fettsäuremethylestern

Influence of light and contents of tocopherols on the oxidative stability of fatty acid methyl esters The oxidative stability of different plant oil based fatty acid methyl esters can be estimated by determining the induction period with the active oxygen method. Measuring the volatile and oil soluble acids for a long period preceding the induction period shows that the values are approaching a certain limit. Even if the esters do not differ dramatically in the composition of fatty acids it is a fact that the different production processes influence the amount of tocopherols significantly. The exclusion of light is more crucial than the exclusion of air when storing plant oil based fatty acid esters.     

Column types for the chromatographic analysis of oleochemicals

Chromatography has developed into one of the principle methods of analysis of oleochemicals. Gas chromatography has been used extensively for the analysis of long-chain fatty acids as well as for the analysis of triglycerides and plant sterols. In recent years, high pressure liquid chromatography (HPLC) has been used for the analysis of triglycerides as well as for other related materials. Specialized gas chromatography columns have been developed for the separation of long-chain fatty acids such as the methyl esters. These columns have generally used high polarity stationary phases which separate fatty acids by degree of unsaturation. A specialized use of these high polarity stationary phases is separation ofcis-trans isomers as well ascis-cis andtrans-trans isomers. In this paper, packed and capillary columns are compared for the separation of thecis-trans isomers of fatty acid methyl esters prepared from a hydrogenated vegetable oil. For HPLC separations, the presence of a double bond is approximately equivalent chromatographically to shortening the alkyl chain by two carbons. The long-chain polyenic acids or ethyl esters thus elute near but are resolved from the short-chain saturated fatty acids or esters. HPLC is the method of choice for relatively complex, high molecular weight, or labile esters, such as those of retinyl or cholesterol. Glyceryl esters are particularly well resolved by HPLC in terms of both total chain length and degree of unsaturation. This technique is also useful for lipid class separations and for the analysis of modified fatty acid products, such as prostaglandins and related materials. In general, these analyses are conducted with octadecyl bonded phase column packings.     

Gaschromatographische und dünnschichtchromatographische Untersuchung von Fettsäuren: Die Anwendung von gepackten Glaskapillarsäulen zur Trennung von cis- und trans-ungesättigten Fettsäuren

Gas Chromatographic and Thin-Layer Chromatographic Studies on Fatty Acids: The Application of Packed Glass Capillary Columns for Separation of cis- and trans-Unsaturated Fatty Acids from Saturated Fatty Acids Packed glass capillary columns were used for the quantitative determination of trans- and cis-unsaturated fatty acids in the presence of saturated fatty acids by gas chromatography. The fatty acids were analyzed as methyl esters after interesterification of the triglyceride samples. The conversion of glyceryl esters of fatty acids into methyl esters could be followed using short GC columns and by thin-layer chromatography.     

Open tubular columns for gas liquid chromatography: Cleaning and recoating procedures

Procedures have been developed that permit the routine reuse of open tubular columns for the analysis of fatty acid methyl esters. Cleaning techniques are given that permit essentially endless recycling of the expensive capillary tubing with nearly 100% success in obtaining excellent columns upon recoating when using polyester liquid phases. Cost, including preparation of column, is equal to or less than the usual conventional packed column. These procedures make it both practical and economical to take advantage of the improved resolution and the reduced time for an analysis obtained with the open tubular column.     

Analysis of processed soy oil by gas chromatography

Two basic gas chromatographic approaches are currently used for the analysis and characterization of processed soy oil and other lipid materials. One approach separates the intact glycerides after silylation whereas the complementary approach determines the fatty acid composition of the glycerides by the formation and subsequent separation of the corresponding fatty acid methyl esters. A brief history of the development of these gas chromatographic procedures and a more detailed discussion of current packed and capillary column technology used for the separation of both intact glycerides and fatty acid methyl esters is presented. Emphasis is placed on the advantages of the newly emerging capillary techniques over the more conventional packed column separations. High resolution chromatograms are shown for the separation of mixed glyceride isomers and also for the separation of unsaturated methyl esters with respect to the number, geometry and position of the double bonds. The separation of the methyl esters can provide information equivalent to classicalcis,cis-lipoxygenase, iodine monochloride titration and infraredrans analyses. Finally, the use of short capillary columns to achieve rapid low cost separations (with resolution equivalent to packed column separations), ideal for quality control, also are discussed.     

The use of SP2340 glass capillary columns for the estimation of thetrans fatty acid content of foods

Glass capillary gas chromatography (GCGC) on 100-m and 60-m SP2340 columns was used for quantitation of thetrans unsaturated fatty acids in shortenings and fast foods. The separation of thecis andtrans octadecenoates on GCGC was evaluated by preparatory argentation thin layer chromatography. In addition, thetrans content of shortening samples obtained by GCGC was compared totrans content determined by infrared analysis. This research conducted by the Science and Education Administration, USDA, on the commercial foods as reported in this paper was limited to analysis of their lipid compositions. The data are reported solely as factual information and are limited to the samples analyzed. No warranty or guarantee is made or implied that other samples of these products will have the same or similar composition. It is the policy of the USDA not to endorse those commercial products used in research over those that were not included in the research.     

Cyclopropenoid Fatty Acids in Malagasy baobab: Adansonia grandidieri (Bombacaceae) Seed Oil

Adansonia grandidieri (bombacaceae family) seed oil gives a positive Halphen test. Composition analysis of derivatized fatty acid methyl esters, in presence of silver nitrate in anhydrous methanol, after chromatography fractionation on silicagel column, were made by gas-liquid chromatography (GLC) using a packed DEGS column. Presence of malvalic and sterculic acids were detected. GLC analysis using glass capillary columns coated with Carbowax 20 M and BDS shows that A. grandidieri seed oil contains mainly palmitic (41%), oleic (22%) and linoleic (12%) acids. Cyclopropenic fatty acid concentration was 14% with 6% for malvalic and 8% for sterculic acids. A slight proportion of dihydrosterculic acid (1.5%) was observed. GLC fatty acid methyl esters analysis, without derivatization, on the two glass capillary columns coated with Carbowax 20 M and BDS gave the same results for cyclopropenic acids content.     

Determination of cholesteryl esters and of cholesteryl and epicholesteryl silyl ethers by capillary gas chromatography

The capillary gas chromatography of cholesteryl esters after splitless injection into a 25-m, OV-1-coated, fused silica WCOT column and a 7-m Silar 10C-coated glass WCOT column is reported. The nonpolar OV-1 column separated the cholesteryl esters principally on the basis of carbon number, but separation of the saturated esters from the unsaturated esters was also achieved. The polar Silar 10C column separated the esters mainly according to the degree of unsaturation. Thus, the 2 column types complement each other in the analysis of nanogram quantities of cholesteryl esters from small samples, such as those from plasma or single arterial atherosclerosis lesions. This technique therefore obviates some of the difficulties of analyzing such cholesteryl ester samples in the form of methyl esters (incomplete transmethylation, and contamination by solvent impurities and/or plasticizer esters). Both columns were also found to be useful for the separation and quantitaiton of thet-BDMS ethers of cholesterol and epicholesterol in mixtures containing various proportions of these epimers.     

Vergleichende Untersuchungen über die gas-chromatographischen Trenneigenschaften der Polyester aus Äthylenglykol und aliphatischen Dicarbonsäuren

Comparative Studies on the Gas Chromatographic Resolving Properties of Polyesters from Ethylene Glycol and Aliphatic Dicarboxylic Acids Ethylene glycol polyesters of aliphatic dicarboxylic acids (C₄-C₁₀) were synthesized. In the gas chromatographic analysis, the relative retention values for n-paraffins, α-n-olefins, fatty acid methyl esters, fatty alcohol acetates and dicarboxylic acid methyl esters are independent of the molecular weights and the end group distribution of the said liquid phases. With the help of the closely agreeing t_R-values GLC-Spectra were drawn, which enable a rapid identification of the compounds mentioned above with the aid of a few test substances. Mixed polyesters behave in the same way.     

Massenspektrometrische Identifizierung von verzweigtkettigen Fettsäuren und Alkoholen aus Bürzellipiden

Mass Spectrometric Identification of Branched Chain Fatty Acids and Alcohols from Preen Gland Lipids The preen gland lipids of some birds were isolated, the waxes separated and resolved into fatty acid and alcohol fractions. The alcohols were oxidised with chromic acid to form the corresponding fatty acids. After methylation with methanolic HCl, the fatty acid methyl esters were investigated by capillary gas chromatography-mass spectrometry. The fatty acids possess mainly mono-, di- and trimethyl branched structures, the branching positions being located preferentially on C–2/–3/–4/–6, C–2,4/–2,6/–2,8/–3,7 C–2,4,6/–2,6,10 and C–6/C–10 or C–14. The mass spectrometric fragmentations which are significant for the structure elucidation of these fatty acid methyl esters are discussed in detail. The investigations indicate a correlation between the composition of the birds to defined orders of the natural system (chemotaxonomy).     

GLC and TLC analysis of isopropylidene derivatives of isomeric polyhydroxy acids derived from positional and geometrical isomers of unsaturated fatty acids

Gas-liquid chromatography (GLC) and thin-layer chromatography (TLC) were used to investigate the isomeric positional geometrical isopropylidene derivatives of nine isomeric dihydroxy esters, four isomeric methyl 9,10-12-trihydroxystearates, and eight isomeric methyl 9,10-12,13-tetrahydroxystearates prepared from unsaturated fatty acids. The isopropylidenes derived fromcis andtrans monounsaturated fatty acids were easily separated on both polar and nonpolar columns. Positional isopropylidenes derived from positional isomers of monounsaturated fatty acids were not separated on either liquid phase but were resolved by TLC. Four of the eight isomeric isopropylidenes derived from the four geometrical isomers of linoleic acid were resolved on the polar column; the other four isomers eluted as a single peak. The four isomeric isopropylidene-trifluoroacetate derivatives derived from ricinoleic and ricinelaidic acids were also resolved on the polar column. GLC analyses were carried out with liquid phases of ethylene glycol succinate methyl silicone polymer (EGSS-X) and methyl silicone polymer (SE-30) packed columns. Isopropylidenes, in addition to their applicability for the resolution of polyhydroxy acid mixtures, are particularly useful for the determination of double bond positions and geometrical configurations of fatty acids without cleavage. Under contract with the U. S. Atomic Energy Commission.     

Strukturaufklärung cyclischer Fettsäuremethylester IV: Über das Auftreten von ω-Phenylalkancarbonsäure-methylestern in cyclisiertem Holz- und Leinöl

Structure Elucidation of Methyl Esters of Cyclic Fatty Acids IV: Occurrence of Methyl Esters of ω-Phenyl Alkanoic Acids in Cyclised Tung and Linseed Oil Methyl esters of cyclic fatty acids (CFA-Me) obtained from alkali cyclised tung and linseed oil were oxidized by performic acid. A series of fractions containing methyl esters of various aromatic fatty acids were obtained by column chromatographic separation of the oxidation products. Whereas the initial fractions consisted of methyl esters of ω-(o-alkylphenyl)alkanoic acids (AFA-Me), the later fractions were found to contain a homologous series of unsubstituted ω-phenyl alkanoic esters. The main component in cyclised tung and linseed oil is the methyl ester of 9-phenyl nonanoic acid. The formation of methyl esters of aromatic fatty acids is discussed.     

Fatty Acid Composition of Danish Margarines

Three groups, including a total of 30 Danish margarines containing at least 10 %, 20 %, or 40 % of linoleic acid, respectively, were analyzed by gas-liquid chromatography using both a 50 m Sil 88 capillary column and two packed columns, SP 2330 and OV-275. The total contents of trans fatty acids ranged as follows: 3.1 %-29.0, 2.9 %-18.3 %, and 2.6 %-8.3 %, respectively, for the three groups. Only in low linoleic acid margarines significant levels of C 20- and C 22-monoenes were found, indicating that these margarines contained partially hydrogenated marine oils. In all samples, the content of trans, trans linoleic acid was less than 1 %.     

An improved method for rapid analysis of the fatty acids of glycerolipids

An improved rapid procedure to determine the fatty acid composition of glycerolipids is described. The procedure includes KOH-catalyzed transesterification and high-speed gas chromatography. Glycerolipids (20–40 mg) were mixed with 2 mL of hexane and 0.2 mL of 2 M methanolic KOH at room temperature for 1–2 min. The fatty acid methyl esters in the hexane layer were analyzed by gas chromatography on 10% SP-2340 at 240°C. Methyl linolenate and docosahexaenoate eluted within 2 and 5 min, respectively. Analysis was thus completed with 5 min for common vegetable oils and 8 min for fish oils. An erratum to this article is available at .     

Application of Methoxy-Bromomercuric-Adduct Fractionation to the Study of Cyclic Fatty Acid Monomers from a Heated Linseed Oil

A linseed oil was heated at 275° C for 12 hr under nitrogen. The triglycerides were isolated from the polymers by gel permeation chromatography on 2μ-styragel columns using tetrahydrofuran (THF) as solvent. One part of the isolated triglyceride fraction was submitted to HPLC on a C₁₈ reverse phase column. The resulting 8 fractions were transformed into methyl esters and hydrogenated on PtO₂ The content of cyclic fatty acid monomers (CFAM) in the different hydrogenated fractions was determined by gasliquid chromatography (GLC) on a Silar-10 C column. The other part of the isolated triglyceride fraction was submitted to the action of BF₃/MeOH. The resulting methyl esters were fractionated by thin-layer chromatography of the corresponding methoxybromomercuric adducts. Five bands were obtained using a mixture of hexane: dioxane (60:40) as the solvent system. A band between the diene and the triene bands contained 40.6% of the total cyclic fatty acid monomers (CFAM) while the diene and the monoene band contained respectively 38.9 and 11.2% of these cyclic components. The diene band and the band between the diene and the triene bands were hydrogenated on PtO₂ The structures of the resulting hydrogenated cyclic fatty acid monomers were studied using a gas-liquid chromatograph coupled with a mass spectrometer (GC-MS).     

Beiträge zur Analytik von Estersulfonaten

Contributions to the Analysis of Sulfonated Esters Several methods for the characterization and determination of α-Sulfo fatty acid methyl esters are described. The sulfonated ester is detected by thin layer chromatography on silica gel plates with tetrahydrofuran + acetone (1+9 v/v) as solvent and with pinacryptol yellow/UV-light for the visualization. Pyrolysis-gas liquid chromatogrphy with heating a sample/P₂O₅-mixture at 400°C yields the chain length distribution of the fatty acids initially used. The amount of an α-sulfo fatty acid ester is determined by extraction with i-propanol and by two-phase titration (Epton). the saponification product of the sulfonated ester is in the i-propanol insoluble part. For a quantitative determination of the α-sulfo fatty acid methyl ester by thin layer chromatography the sample solution is directly applied to the thin layer plate. A range of defined volumes, with increasing amounts of the sample are applied to the plate by means of an applicator. The chromatograms are visually compared. Ion chromatogrphy with the mobile phase, NH₃/Acetonitrile separates the α-sulfo fatty acid esters by chain-length. Determination is achieved by standards with defined chain-length.