Separation of polyunsaturated fatty acids by argentation thin layer chromatography

A single step, silver nitrate thin layer chromatographic procedure which separates a methyl ester mixture containing 0–6 double bonds is described. Purity of each ester recovered from the silver nitrate plate was 98–99%. Recovery of the esters ranged from 100% for saturates to 77% for pentaenes.     

Separation and identification of amino acids from lignite humic acids by thin layer chromatography

Thin layer chromatography with and without temperature gradient was used to identify ten amino acids in the humic acid hydrolysate of Rovinari lignite, using cellulose and volcanic tuff as stationary phases. The acids found were L-leucine, isoleucine, phenylalanine, L-valine, tyrosine, proline, L-alanine, glutamic acid, threonine and L-lysine.     

Separation of conjugated bile acids by reverse phase thin layer chromatography

Seven conjugated bile acids were separated by 1-dimensional reverse phase thin layer chromatography using ethanol/0.3 M calcium chloride/dimethylsulfoxide (25∶25∶2) as mobile phase.     

Identification of nylons by thin layer chromatography

The composition of nylons by ω-amino-carboxylic acid monomers, dicarboxylic acids, and diamines is identified by thin layer chromatography, using their acid hydrolysates and determining the corresponding R_f values.     

Determination of cyclic fatty acids by gas-liquid chromatography

A method is described to determine cyclic fatty acids in cyclic monomers by gas-liquid chromatography (GLC), which separates saturated straight-chain esters from cyclic esters. The content of cyclic esters can be determined by integration of the area on the chromatograph under the cyclic peaks. GLC was applied to cyclic monomers made from linseed oil and from linolenic acid. Samples of both hydrogenated and nonhydrogenated cyclic monomers were analyzed; however, more reliable results were obtained on the hydrogenated samples. The results show a standard deviation of 0.25 for linseed oil and 0.36 for linolenic acid. Accuracy of the analysis was established by comparing data with that obtained by crystallization. The GLC method is approximately three times faster. Presented at the AOCS meeting, New Orleans, La., 1962. A laboratory of the No. Utiliz. Res. & Dev. Div., ARS, U.S.D.A.     

Characterization of unsaturated fatty acids by gas-liquid chromatography

The equivalent chain length (ECL) has been determined on 79 methyl esters of unsaturated fatty acids and on 7 ethyl esters by gas chromatography. Ethylene glycol succinate (EGS), diethylene glycol succinate, β-cyclodextrin acetate and Apiezon L were chosen as the liquid phases to be used. For methyl esters of mono- and polyenoic acids, the differences between ECL on EGS and ECL on Apiezon L approximate 0.84 per double bond. For positional isomers, the ECL on both EGS and Apiezon L are usually greater for the isomer having the longer proximal end of the molecule (smallest ω value). In these terms a triple bond is approximately equal to three double bonds. Esters of nonconjugated dienoic and trienoic acids of the same chain length are not separable on Apiezon L if their proximal structures are the same. This also applies to tetraenoic and pentaenoic acids of the same chain length and the same proximal structure. Conjugation of double bonds, either with the ester carbonyl group or with themselves, yields ECL values on Apiezon L greater than the number of carbon atoms in the acid. Monounsaturated and nonconjugated polyunsaturated esters have ECL values on Apiezon L lower than the number of carbon atoms of the acid. The ECL values of ethyl esters of 18 and 20 carbon acids are greater than the corresponding methyl esters on Apiezon L. Presented at the Chicago meeting of the American Oil Chemists’ Society, Oct. 13, 1964.     

Simultaneous detoxification and preparative separation of chlorogenic acid from Eupatorium adenophorum by combined column chromatography

An efficient method for simultaneous detoxification and preparative separation of chlorogenic acid from Eupatorium adenophorum was developed. The entire procedure consisted of two separation steps. The first step was enrichment of chlorogenic acid from the crude extract by NKA-II macroporous resin. The purity of chlorogenic acid increased from 5.3% to 20.9% with a recovery of 88.7%. Subsequently, polyamide resin was used to achieve a higher purity. After the polyamide resin treatment, the main toxin 9-oxo-10,11-dehydroageraphorone was removed and the purity of chlorogenic acid reached 86.5% with a recovery of 84.8%. It provided a new way for the utilization of E. adenophorum.     

离子液体作薄层色谱添加剂对氨基酸分离的研究

将1-丁基-3-甲基咪唑基四氟硼酸盐([Bmim]BF4)离子液体作为薄层色谱展开剂添加剂,讨论了[Bmim]BF4浓度对精氨酸和赖氨酸两种碱性氨基酸分离的影响.结果表明:添加离子液体能有效改善碱性氨基酸的展开效果,而且分析物的Rf值随离子液体浓度的增加而增加,浓度增加到一定后Rf保持不变.另外,比较了[Bmim]PF...     

Analysis of long chain sultones by thin layer chromatography

The separation and semiquantitative estimation of nine C₁₄ sultones by thin layer chromatography (TLC) on silica gel is reported. Vapor phase charring gives detection limits of several ppm in olefin sulfonate, ethoxylated alcohol sulfates, and formulated products. Isopropyl ether is the solvent of choice, and two-dimensional TLC with this and a chlorinated solvent mixture gives an exclusive sultone area, as well as added sensitivity. Simplified preparative TLC on plates with preadsorbent is described for confirmation by independent analytical methods.     

Determination of available lysine in pulses by thin layer chromatography

Estimation of available lysine in five pulse samples was carried out by a thin layer chromatographic technique. Results revealed that the available lysine values in all the cases were to some extent lower than the total lysine values.     

Detection of palm oil in vanaspati by thin layer chromatography

Palm oil (raw or refined), as such, or the unsaponifiable matter of palm oil and vanaspati (mostly hydrogenated soybean oil containing 5% sesame oil), when separated on a silver nitrate impregnated Silica Gel G plate or a Silica Gel G plate using (a) hexane/ether/acetic acid (80:20:1.5) or (b) chloroform, respectively, for development showed distinct differences. On the basis of this, two systems have been suggested for the detection of palm oil in vanaspati. About 5% adulteration can be detected by the first method and 10% by the second.     

A complete separation of lipids by three-directional thin layer chromatography

A novel three-directional thin layer chromatography (TLC) method is reported by which all the polar and neutral lipids are isolated on a single TLC plate. Following resolution of the phospholipids by two-directional TLC, lipids are visualized by ultraviolet light after spraying with 2′,7′-dichloro-fluorescein. A line is drawn across the plate, parallel to the second direction of development, separating the resolved phospholipids and the neutral lipids concentrated along the solvent front. The TLC plate is then chromatographed in the reverse direction of the second development to resolve the neutral lipids. By exposing the lipids to HCl fumes after the first development, the plasmalogen content of the lipids may also be determined. This new technique is rapid and lends itself to qualitative and quantitative analyses of total lipids. Contribution no. 1163 from the Animal Research Centre.     

Analytical fractionation of complex lipid mixtures: DEAE cellulose column chromatography combined with quantitative thin layer chromatography

A quantitative chromatographic procedure for the fractionation of complex lipid mixtures is described. The method utilizes diethylaminoethyl (DEAE) cellulose column chromatography followed by thin layer chromatography (TLC). Spots produced in TLC are charred with sulfuric acid-potassium dichromate and heat and are then measured by quantitative densitometry. Results obtained with beef brain and beef heart mitochondrial lipids are presented, and the close correspondence between column isolation procedures and the new procedure is demonstrated. Methods utilizing only column chromatography, column chromatography and TLC, and one- and two-dimensional TLC without column chromatography are compared.     

Quantitative determination of isomeric glycerides,free fatty acids and triglycerides by thin layer chromatography-flame ionization detector system

Partial glyceride mixtures, which include 1-monoglyceride, 2-monoglyceride, free fatty acid, 1,2-diglyceride, 1,3-diglyceride and triglyceride, could be separated from each other on a 3% boric-acid-impregnated Chromarod S-II (silica gel sintered quartz rod) with either chloroform/acetone (96∶4, v/v) or chloroform/acetone/acetic acid (100∶1∶1, v/v) as the developing solvent mixtures. The components separated on the boric-acid-impregnated rod were automatically quantitated in a hydrogen flame ionization detector (Iatroscan). The relative responses of 1,2-diglyceride, 1,3-diglyceride, free fatty acid and triglyceride were slightly lower than theoretical responses based on weight percentage, whereas 1-monoglyceride and 2-monoglyceride showed slightly higher responses. These responses were converged within a maximal error of 5–10% (SD). Boric-acid-impregnated rods could be used repeatedly, ca. 5 times without any reconditioning procedure. Part of this investigation was reported at the 2nd JOCS-AOCS joint meeting, San Francisco, May 1979.     

The thin layer chromatography of vat dyes

The identification and separation of vat dyes by thin layer chromatography has been investigated with reducing and non-reducing systems. The results showed that the chromatograms on silica gel plates obtained by non-reducing systems at 100 or 120°C were fast, reproducible and easy to control. Nine non-reducing eluents were developed, producing good migration and resolution of 21 vat dyes. Analyses of the chromatograms revealed that the R_f, values varied with the temperature of the system, the chemical structure of the vat dyes and the nature of adsorbent, as well as with the eluents used. The effects of molecular masses of the vat dyes on the R_f values were less significant. Despite the successful use of a novel reducing agent for vat dyes, the chromatography of reduced dye was largely unsatisfactory. The use of reversed-phase t.l.c. plates was examined and showed little benefit.     

薄层色谱分析在层析分离过程中的应用

介绍了薄层色谱分析方法对层析分离过程的控制性分析和优化作用。     

Quantitation and distribution of altered fatty acids in frying fats

The distribution and quantity of polar compounds and altered fatty acids in used frying oils, collected by Food Inspection Services of the Junta de Andalucía in Spain, was measured. Additional samples evaluated were sunflower oil, high-oleic sunflower oil, and palm olein that were subjected to thermoxidation and frying in laboratory experiments. A combination of adsorption and high-performance size-exclusion chromatography was applied to the oil samples both before and after transesterification. Through analysis of fatty acid methyl ester derivatives, differentiation of four groups of altered fatty acids (oxidized monomers, nonpolar dimers, oxidized dimers, and polymers) could be attained. Evaluation of real frying samples with polar compound levels around the limit for fat rejection (21.1–27.6% polar compounds) gave values of total altered fatty acids ranging from 8.1 to 11.3%, and levels higher than 20% were found in the most degradated samples. The results obtained clearly support the need for control and improvement of the quality of used fats in fried-food outlets.     

Detection of adulteration of olive oil by argentation thin layer chromatography

Minute amounts of adulterant seed oils in olive oil can be detected by GLC analysis of fatty acids of the polyunsaturated triglyceride fraction, obtained by TLC on silver nitrate impregnated silica gel. Every possible effort was made to avoid any critical or time consuming manipulation in this method in order to develop it as a routine testing procedure. A complete analysis is possible in less than 2 hr and the detection of as low as 2% adulteration by other seed oils is accurate and reliable.