The separation of glycerides by liquid-liquid column partition chromatography

A liquid-liquid partition chromatography method was developed to separate triglycerides. The solvent was a two phase mixture of acetone, heptane, and water supported on silane treated celite. A study was made of the best means for equilibrating the solvents and support, packing the column, and introducing the sample. The effect of various operating variables such as flow rate, sample size, column length, and solvent compositions was studied using trilaurin and trimyristin as model glycerides. Under the best conditions achieved, it was calculated that glycerides differing by two carbon atoms or one double bond would not separate completely, but glycerides differing by two double bonds or four carbon atoms would be separated. Cocoa butter, a relatively simple triglyceride, was fractionated, and the fatty acid composition of each fraction was determined by gas chromatography. The glyceride composition was calculated and compared with theoretical compositions. The results indicate that useful glyceride separation can be obtained with this system. Probably even more useful separations could be obtained if a more sensitive device were used to detect the triglycerides in the effluent. This would allow the use of solvent compositions which give larger retention volumes and more plate efficiency. Journal Paper No. J-4517 of the Iowa Agricultural and Home Economics Experiment Station, Ames, Iowa, Project No. 1517. Presented at the AOCS meeting in Toronto, Canada, 1962. Based on a thesis presented by B. C. Black in partial fulfillment of the requirements for a master’s degree.     

The estimation of lactic acid in lactylated monoglycerides and shortenings containing lactylated monoglycerides

A titrimetric method has been presented for the determination of lactic acid in lactylated monoglycerides and shortenings containing these products, when the only water soluble acid present is lactic acid. Analyses by this method: of knowns, samples from a material balance test, and commercial products, indicate that it is applicable to these types of product. Comparison of analyses of the material balance samples and commercial products by the titrimetric method and the colorimetric p-phenylphenol method indicated that the latter gave lower and more variable results.     

A method for the determination of the water-insoluble combined lactic acid content of shortenings containing lactylated emulsifiers

Shortenings containing glycerol lactopalmitates and glycerol lactostearates are analyzed for water-insoluble combined lactic acid content using a procedure adapted from that of Barker and Summerson (1). Water-soluble constituents are extracted from a chloroform solution of the shortening. The water-washed shortening is saponified and then acidified to release the lactic acid, which is degraded to acetaldehyde by heating with concentrated sulfuric acid. The acetaldehyde is reacted withp-phenyl phenol is concentrated acid solution to produce a purple colored reaction product. The intensity of the color is proportional to the concentration of the acetaldehyde. Absorption is read at 570 mμ using a lithium lactate solution as a standard. The method has been applied to the analysis of shortenings containing from 0.70 to 1.10% water-insoluble combined lactic acid.     

Determination of total and water-insoluble-combined lactic acid in lactic acid modified fatty glycerides

Analytical methods for the determination of total and water insoluble combined lactic acid in lactic acid modified fatty glycerides are described. The acids are liberated from their esters by saponification. Lactic acid is determined by simple acid-base titration after removal of fatty acids via liquid-liquid extraction. Water soluble constituents are extracted from a dichloro-methane solution of the esters with 5% aqueous sodium sulfate prior to determination of water insoluble lactic acid. Methods are rapid, simple, and suitable for use in a plant control laboratory. Extension of the procedure provides for the simultaneous determination of fatty acid and glycerine on a single sample.     

Preparation of highly purified fatty acids via liquid-liquid partition chromatography

The application of reversed-phase, liquid-liquid partition chromatography to the preparation of highly purified methyl esters of fatty acids is described. The parameters of fractionation of methyl esters by this method are demonstrated with model mixtures of these compounds. Model mixtures are also used to demonstrate the use of adsorption chromatography on columns of silicic acid, impregnated with silver nitrate, in conjunction with liquid-liquid partition chromatography to eliminate fractional distillation in the preparation of polyunsaturated methyl esters. The formation of artefacts of 4, 5 and 6 double bond methyl esters during fractional distillation and their fractionation is described. The use of liquid-liquid partition chromatography for preparative purposes on a large laboratory scale is demonstrated by the preparation of pure methyl linolenate from linseed oil esters. Methyl arachidonate, eicosapentaenoate, docosapentaenoate and docosahexaenoate are also prepared in high purity. Supported in part by the U. S. Public Health Service, NIH grant A-5018, and in part by a contract with the U. S. Dept. of Interior, Fish and Wildlife Service, Bureau of Commercial Fisheries. Presented at the AOCS Meeting in Toronto, Canada, 1962.     

Triglyceride analysis by consecutive liquid-liquid partition and gas-liquid chromatography.Ephedra nevadensis seed fat

The triglyceride composition ofEphedra nevadensis seed fat, which contains 16 different fatty acids, has been analyzed by a combination of liquid-liquid partition and gas-liquid chromatography. Triglycerides were first separated by liquid-liquid partition chromatography. The recovered fractions were then analyzed by gas-liquid chromatography to determine the molecular weights of the triglycerides present. Consecutive separation by these two techniques resolved this complex seed fat into 30 different triglyceride groups. A method for preparative liquid-liquid partition chromatography of triglycerides is described in detail. Highly unsaturated triglyceride mixtures are easily resolved on the basis of “partition number” by using a hexadecane/nitroethane partition system. Presented at the AOCS Meeting, Chicago, October, 1967.     

Monoglyceride content in glycerides by means of gas chromatography

The “Joint Committee for the Analysis of Fats, Oils, Fatty Products, Related Products and Raw Materials (GAFett)” has developed the following method for the determination of the monoglyceride content in fats and fat derivatives. It is intended to include this method in Section C, Chapter VI of the German Standard Methods.     

HPLC法测定苹果酒中苹果酸及乳酸含量

建立了HPLC测定苹果酒中苹果酸及乳酸含量的方法,即采用配紫外检测器及Symmetry C18（3.5μm×4.6mm×75mm）色谱柱的液相色谱仪,柱温25℃,流动相为含0.1%甲酸的甲醇水溶液,流速0.5mL/min,检测波长210nm,进样量20μL,通过外标法定量研究苹果酒中苹果酸及乳酸的含量。研究结果表明：该法定量线性关系良好（苹果酸标准曲线的线性相关系数R~2为0.9969,乳酸的R~2为0.9999）;日内进样保留时间相对标准偏差（RSD）在0.12%以内,峰面积RSD在2%以内,日间进样保留时间的RSD在0.12%以内,峰面积的RSD在1.82%以内;苹果酸的最低检出限（LOD）（S/N≥3）可达0.43mg/L,最小检测量（LOQ）（S/N≥10）可达1.30mg/L,乳酸的LOD可达1.12mg/L,LOQ为3.36mg/L。上述方法对于测定苹果酒中苹果酸及乳酸含量线性关系良好、重现性好、灵敏度高。     

Separation of lipids containing phytanic acid by thin-layer chromatography

Cholesteryl phytanate and triglycerides containing phytanic acid were separated from their normal fatty acid analogs by thin-layer chromatography. The presence of the branched-chain fatty acid makes the lipid less polar, and this effect becomes more pronounced as the number of phytanic acid residues in the triglycerides is increased. Phytanic acid was prepared from commercial phytol by catalytic hydrogenation, followed by catalytic oxidation. It contained 5% pristanic acid.     

Glyceride studies. Part IV. The component glycerides of ten seed oils containing linoleic acid

The component glycerides of ten seed oils (safflower, tobacco, sunflower,Argemone mexicana, maize, cotton, groundnut,Macadamia ternifolia, Gmelina asiatica, andMadhuca latifolia) have been estimated by chromatographic procedures. The results agree with those obtained by lipolysis or calculated directly from the component acids on the basis of the theory of positional distribution.     

液液萃取-液相色谱法测废水中的氯酚

建立液液萃取-液相色谱法测废水中2,4-二氯酚、2,4,6-三氯酚、五氯酚的方法。对废水样品用硫酸酸化至pH值为2³,用二氯甲烷20 mL分2次萃取,合并有机相,再用10 mL浓度为0.5 mol/L K2CO3分2次萃取,定容后,采用可变波长紫外检测器进行定量分析。结果表明,3种氯酚的最低检出质量浓度为2.63,用二氯甲烷20 mL分2次萃取,合并有机相,再用10 mL浓度为0.5 mol/L K2CO3分2次萃取,定容后,采用可变波长紫外检测器进行定量分析。结果表明,3种氯酚的最低检出质量浓度为2.6³.7μg/L,回收率为88.4%3.7μg/L,回收率为88.4%¹06%,测定结果的相对标准偏差为2.67%106%,测定结果的相对标准偏差为2.67%⁴.55%,R2为0.999 74.55%,R2为0.999 7⁰.999 9。该方法所需前处理设备少,操作简单,具有较好的准确度和精密度,适用于废水中2,4-二氯酚、2,4,6-三氯酚、五氯酚的检测。     

Glyceride studies. Part III. The component glycerides of five seed oils containing linolenic acid

The component glycerides of linseed, wild rose, candlenut, soya and stillingia oils have been estimated by chromatography on thin layers of silica impregnated with silver nitrate. The separated glycerides are identified, qualitatively and quantitatively, by gas-liquid chromatography (GLC) of their methyl esters in presence of added methyl heptadecanoate as an internal standard. The results agree with those obtained by lipolysis or calculated directly from the component acids on the basis of the theory of positional distribution.     

Analyses of lipids and oxidation products by partition chromatography. Fatty acid hydroperoxides

A liquid partition chromatographic method was developed to isolated and determine hydroperoxides in autoxidized fatty acids or their methyl esters. By the use of benzene containing 2 to 4% methanol as the mobile solvent, the hydroperoxides were separated from unoxidized fatty acids or methyl esters and from secondary and polymeric decomposition products. In the analyses of oxidized fatty acids, diethyl ether was necessary to elute the secondary decomposition products. Saponification of autoxidized fatty esters destroyed the peroxides as determined iodometrically, but the resulting acids contained a fraction which was eluted in the same position as hydroperoxide acids. Evidence showed that this fraction is a monomeric hydroxy fatty acid containing conjugated cis-traux and trans-trans unsaturation. Fatty ester hydroperoxides were isolated chromatographically in yields and purity comparable to those reported in the literature by countercurrent distribution. The concentrations of methyl linoleate hydroperoxide determined chromatographically were smaller than indicated by the peroxide value and diene conjugation of the autoxidized methyl linoleate. This is a laboratory of the Northern Utilization Research and Development Division, Agricultural Research Service, U.S. Department of Agriculture.     

分散液液微萃取高效液相色谱法测定环境水样中硝基苯

本文对分散液液微萃取（DLLME）技术萃取水样中痕量硝基苯进行了研究,建立了硝基苯的分散液液微萃取-高效液相色谱-紫外分析方法。在20μL氯苯萃取剂、1.00mL乙腈溶液、pH=6、离子强度为3%NaCl和10min萃取时间下,DLLME对硝基苯的萃取效果最佳。方法的线性范围为0.1～50.0μg/mL,线性较好,相关系数R2为0.9993,检出限和定量限分别为1.1ng/mL和2.9ng/mL。方法的加标回收率范围为92.66%～96.62%。所建方法能对实际水样中的硝基苯进行测定。     

柠檬酸甘油单,二酸酯合成过程中沉淀物的分析

对柠檬酸和单甘酯酯化反应制取柠檬酸甘油单、二酸酯过程中产生的沉淀进行了红外光谱分析,并对沉淀产物的原因提出了合理的解析。     

Unstructured mathematical model for biomass,lactic acid and bacteriocin production by lactic acid bacteria in batch fermentation

BACKGROUND: A simple macroscopical model was proposed to describe the fermentation kinetics of growth, bacteriocins and lactic acid production by Lactococcus lactis and Pediococcus acidilactici in a batch system. The equations used were: the logistic reparametrized for growth, the Luedeking–Piret model for bacteriocin production, the maintenance energy model for glucose consumption; and the homofermentative balance equation for lactic acid formation. RESULTS: In all the cultures, the mathematical models, consistents and robusts, adjusted, perfectly, the experimental kinetic profiles. Also, the corresponding kinetic parameters were significant, so much biological as statistically. CONCLUSIONS: The group of integrated equations used, besides showing high accuracy in predicting the studied bioproductions, established a useful tool for the control of lactic acid bacteria kinetics in bioreactors in terms of its statistical consistency. Copyright © 2007 Society of Chemical Industry     

Isolation and characterization of glycerides in human hair lipids by thin-layer and gas chromatography

Techniques for the quantitative analysis of hair lipids using thin-layer chromatography (TLC) together with a proximate analysis of components in one sample deduced by these criteria are presented. Mono-, di- and triglycerides were separated by TLC using Silica Gel G as adsorbent. The chromatoplates were developed with 98% acetone+2% petroleum ether. Glycerides moved with the solvent front. The requisite portions were scraped off the plates and extracted with acetone and ether. Further TLC, limiting the migration of triglycerides and diglycerides was afforded by use of 95% ethanol as solvent in one direction while monoglycerides moved with the solvent front. For the separation of monoglycerides, chloroform was used as solvent in a second direction. Reference standards and several mixtures were run simultaneously and the spots identified by charring with concentrated sulfuric acid containing dichromate. Additional checking was effected by IR spectra. For determination of glyceride composition, methyl esters of the component fatty acids were prepared by transesterification and submitted to gas chromatography. Comparison of the levels of each of the constituent fatty acids showed no remarkable differences between the three classes of glycerides in one hair lipid pool. Although certain discrepancies in the amounts of a few fatty acid components might be construed for one pool of lipids from hair of white full-headed men (WF-9A) in contrast to findings with two Negro pools, no unequivocal conclusions can be drawn presently.