Systematic protocol for the accumulation of fatty acid data from multiple tissue samples: Tissue handling,lipid extraction and class separation,and capillary gas chromatographic analysis

A systematic procedure was developed for detailed fatty acid profiling of both neutral and polar lipid fractions isolated from hundreds of related bovine muscle and adipose tissue samples. A regimen was established for a nonbiased handling of tissue samples, which included their handling in a predetermined random order. Lipid class separation was accomplished concomitantly during the extraction of the tissues by a selective dry column method, which allowed a detailed analysis of minor but important polyunsaturated fatty acids associated with the polar fraction. Neutral lipids were derivatized to fatty acid methyl esters (FAME) by a literature procedure. However, to protect against lysis of plasmalogens in the polar fraction, a modified nonacidic esterification procedure was developed. FAME profiles were obtained on a program-mable high resolution capillary gas chromatograph (GC). Run programs for unattended GC operation and data storage are described. By this overall procedure, the quantitation and peak identification were obtained for major and minor fatty acid constituents from bovine tissue in a manner that prepares for valid statistical interpretation of the resulting data.     

Isomerization and hydrogenolysis of trimethylbenzenes with platinum on acidic and nonacidic supports

For commercial high-pressure naphtha reforming conditions, platinum has a similar demethylation activity when supported on acidic or nonacidic alumina. Platinum on nonacidic alumina exhibits a low trimethylbenzene isomerization activity under conditions where platinum on an acidic support produces an equilibrium mixture. The xylene isomers produced by demethylation are consistent with a demethylation mechanism without isomerization. The relative rates of demethylation and isomerization of 1,3,5-trimethylbenzene should be a method of measuring the hydrogenation and acidic functions of bifunctional catalysts. The results also demonstrate that the aromatics formed by alkane dehydrocyclization under reforming conditions do not extensively isomerize when a nonacidic support is used.     

Extraction of Spent Bleaching Earth in the Production of Renewable Diesel

The extraction of oils based on animal fat and vegetable oil from two types of spent bleaching earths, namely from the acidic sepiolite and the nonacidic palygorskite, was investigated by the Soxhlet method with hexane as a solvent. The yields of oil were independent of the feedstock, whereas a much lower oil yield was obtained with palygorskite exhibiting also a smaller surface area as compared to sepiolite which provided a higher yield. The glyceride compositions were very similar in bleached and extracted oils, while slightly lower melting and crystallization energies were determined by differential scanning calorimetry for the extracted oils bleached with acidic clay indicating minor hydrolysis of triglycerides.     

Characterization of minor constituents in commercial oleic acid

Minor constituents were isolated from a mixture of commercial oleic acid manufactured from beef tallow by 10 different companies. Silicic acid was used as an adsorbent to isolate the minor constituents. They were first separated into acidic and nonacidic fractions. Each fraction was then separated into numerous subfractions by stepwise gradient elution liquid chromatography, using silicic acid as the adsorbent. The subfractions which had an adverse effect on the color stability of oleic acid during heating were characterized with functional group analysis, elemental analysis and IR spectrophotometry. The minor constituents amounted to ca. 1.18% of the commercial oleic acid. They were complex mixtures with multiple functional groups. Some of the subfractions contained 2\s-3 times as much oxygen in the molecule as oleic acid. They had molecular weights ranging from 308 to 830 which are from monomers to trimers of oxidized oleic acid. These minor components contained carbonyl, ester and hydroxyl groups and double bonds. Some of the nonacidic minor constituents may contain amide groups. Most of the acidic subfractions were dark red, viscous liquids and the nonacidic subfractions were dark green or greenish-brown, semisolid substances. A relationship was established that the greater the polarity of the minor constituents, the greater is its adverse effect on the color stability of oleic acid during heating. Paper of the Journal Series, New Jersey Agricultural Experiment Station, Cook College, Rutgers, The State University of New Jersey, New Brunswick, NJ 08903.     

Rapid Separation of Carrier-Free 95Zr from 95Nb Using MnO2 Column

Abstract

An efficient and simple method is presented for the radiochemical separation of ⁹⁵Zr from ⁹⁵Nb in a carrier-free state. ⁹⁵Zr is desorbed quantitatively from the MnO₂ column using a 3 M HNO₃ + 0.05 M HF solution. By following the recommended procedure, a decontamination factor higher than 10⁵ is achieved. The radionuclidic purity of the separated ⁹⁵Zr has been ascertained by gamma-ray energy measurements as well as by a radiochemical method. The entire procedure takes less than 20 min.     

一种改进的多元精馏塔动态模型

综合了精馏塔的物料及能量平衡、塔板水力学方程、塔板效率及再沸器动态特性,给出一种改进的非理想多元物系精馏塔通用动态数学模型.增加了汽液平衡计算,从而弥补了文献[1]所提出的动态模型的缺陷,提高了其精度和通用性.模型仿真算法采用Gear积分方法,稳定性好,对解刚性比很高的精馏塔微分方程组十分有效.通过对某丙烯腈萃取精馏塔的仿真表明,该动态模型能够较好地反映对象的动态形为.     

Fatty acid distribution of fats,oils and soaps by high-performance liquid chromatography without derivatization

A high-performance liquid chromatography (HPLC) procedure without derivatization was developed for quantitating fatty acid components of various soap-related fats and oils, as well as for the direct quantitation of fatty acids from soap. The fatty acids are detected by refractive index after isocratic reverse-phase chromatography. The method has been developed with radial compression and stainless-steel column technology. The triglycerides are saponified and acid-hydrolyzed into fatty acids, and they are dissolved in a solvent and injected. The soaps are dissolved in methanol and injected into the HPLC, where they are acid-hydrolyzed directly on the column by an acid-modified mobile phase. The total run time after injection is approximately 20 min, with quantitation performed on an NEC Powermate^® computer driven by PE/Nelson Analytical Software. The typical carbon chains analyzed are from C6 to C20.     

Separation of underivatized gangliosides by ion exchange high performance liquid chromatography

A procedure is described which separates neutral glycolipids from gangliosides, and which separates the gangliosides into classes, based on their number of sialic acid residues. In addition to separation into mono-, di- and trisialoganglioside classes, there is purification of individual disialoganglioside species. The procedure uses a commercially available—NH₂ high performance liquid chromatography (HPLC) column, which normally is used as an adsorption column. In this method the column is modified by protonation, to pH 5.4, so that it exhibits ion exchange as well as adsorption properties. Sensitive, nondestructive detection of eluent peaks is accomplished by monitoring continuously at 210 nm, a wavelength near which underivatized glycosphingolipids have absorbance maxima and which also will clearly detect most possible contaminants. An entire run, including re-equilibration of the column, takes two hours.     

Aromatization of heptanes,ethylcyclopentane, and cycloheptane over “nonacidic” platinum-alumina catalyst. Comparison of the mechanisms of aromatization over chromia-alumina and over platinum-alumina catalysts

n-Heptane, 2- and 3-methylhexane, ethylcyclopentane, and cycloheptane were passed in the presence of hydrogen at 500 °C over “nonacidic” platinum-alumina catalyst containing 3% by weight of platinum. The conversion ranged between 12 and 26%, depending on the interval of time the product was removed for analysis. In the case of cycloheptane, however, the conversion amounted to 98% during the first 30 min on stream and with time, during the approximate period between 2 and 3 h, it decreased to 69%. The products from the reaction contained besides toluene, also hydrocarbons resulting from a skeletal isomerization and dehydrocyclization of the original hydrocarbons, and to a smaller extent from a bond shift process, and a repetitive 1,5-ring closure followed by hydrogenolysis. Using 1,1-dimethylcyclohexane as a model compound, it was shown that the skeletal isomerization accompanying the aromatization of the seven-carbon hydrocarbons does not proceed through cationic intermediates. A survey of the literature relating to the mechanism of aromatization of hydrocarbon over “nonacidic” chromia-alumina and platinum-alumina catalysts is presented, and the differences between the two mechanisms are discussed.     

Characterization of the nonvolatile compounds formed during the thermal oxidation of 1-linoleyl-2,3 distearin: I. The nonacidic fraction

A compound isolated from the nonacidic fraction of thermally oxidized 1-linoleyl-2,3-distearin was shown to be 18-pentatriacontanone. A combination of schemical and instrumental analyses was used to determine the structure. This work represents a portion of a thesis presented by L. R. Wantland as partial fulfillment of the requirements for the Ph.D. degree at the University of Illinois.     

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.     

The second law optimal state of a diabatic binary tray distillation column

A new numerical procedure to minimize the entropy production in diabatic tray distillation columns has been developed. The method was based on a least square regression of the entropy production at each tray. A diabatic column is a column with heat exchangers on all trays. The method was demonstrated on a distillation column separating propylene from propane. The entropy production included contributions from the heat transfer in the heat exchangers and the mass and heat transfer between liquid and vapor inside the distillation column. It was minimized for a number of binary tray distillation columns with fixed heat transfer area, number of trays, and feed stream temperature and composition. For the first time, the areas of heat exchange were used as variables in the optimization. An analytical result is that the entropy production due to heat transfer is proportional to the area of each heat exchanger in the optimal state. For many distillation columns, this is equivalent to a constant driving force for heat transfer. The entropy production was reduced with up to 30% in the cases with large heat transfer area and many trays. In large process facilities, this reduction would ideally lead to 1-2 GWh of saved exergy per year. The most important variable in obtaining these reductions is the total heat transfer area. The investigation was done with a perspective to later include the column as a part in an optimization of a larger process. We found that the entropy production of the column behaved almost as a quadratic function when the composition of the feed stream changed. This means that the feed composition is a natural, easy variable for a second law optimization when the distillation column is a part of a process. The entropy production was insensitive to variations in the feed temperature.     

Ultramicro fatty acid analysis of polar lipids: Gas-liquid chromatography after column and thin-layer chromatographic separation

A procedure is described for the analysis of the fatty acid composition of polar lipid classes in the nanogram range. The lipids are first fractionated by column chromatography followed by further separation into pure lipid classes by thin-layer chromatography. Lipid spots scraped from the thin-layer plates are esterified directly (i.e., without prior elution) with 6% sulfuric acid in methanol. The methyl esters are then analyzed by gasliquid chromatography with a hydrogen flame ionization detector. Samples of 200 nanograms or less give accurate results with helium as carrier gas, oxygen rather than air to support combustion, careful adjustment of the recorder and general attention to optimum electrical connections, dissociation of the column oven from the recorder and electrometer, and careful preconditioning of columns. Under proper conditions the base line is stable and a 10% of full scale deflection of the recorder can be obtained from 1 nanogram of a methyl ester, allowing highly precise analyses of fatty acid composition from the amount of lipid obtainable from one spot on a thin-layer chromatogram. Control studies demonstrated that extraneous peaks did not arise from the procedure or from the sphingosine and dihydrosphingosine of sphingolipids. The thin-layer chromatographic procedure did not influence the fatty acid composition of a pure sample of glucocerebroside isolated by column chromatography and the method was applied to lecithin and sphingomyelin or normal and pathological human brain specimens.     

Machining high quality superconducting rings from top seeded melt grown samples

Abstract

A drilling procedure for obtaining superconducting rings from top seeded melt grown samples is reported. The method described is based on the use of a column drilling machine with a copper–diamond drill bit. Modifications have been made in order to avoid structural damage to the superconductor during drilling. The success of the technique was assessed by measuring the critical current of samples before and after machining, with similar values obtained in both cases.     

抗蚜威液相色谱分析

本文介绍以硅胶正相柱、石油醚和异丙醇为流动相的色谱系统，分离抗蚜威，经紫外检测器先定量的方法，并对方法的线性关系，精密度、准确度进行了评估。     

壁纸中残留氯乙烯单体的顶空气相色谱法分析

采用固上顶空气相色谱法,对壁纸中氯乙烯单体的残留量进行了测定。采用氯乙烯单体标准溶液作为标准物质,克服了使用气体标准物质操作过程繁琐的缺点,简化了测试过程。使用毛细管柱进行检测,克服了填充柱分辨率不高的缺点,提高了检测的分辨率。并且对气相顶空条件和色谱条件进行了优化,提高了该方法的可操作性、灵敏度和精密度。回归方程为y=22.4363x-0.2185,回归系数r=0.9997,加标回收率在88%～100%之间。通过测定壁纸产品取得了良好的效果。     

Rapid procedure for the determination of residual acetone and 2-propanol in oilseed meals and flours

A simple, rapid elution gas chromatographic method was used for quantitative determination of acetone or 2-propanol in finely ground, extracted oilseed meals and flours. In the procedure, a 0.05 g sample of oilseed meal or flour was placed between 2 small glass wool plugs in a liner of the injection port of a gas chromatograph. Water (250 μl) was added over the glass wool sandwich, and the liner was placed in the heated injection port and firmly secured. Acetone or 2-propanol and other volatiles were rapidly eluted from the sample onto the column by the combined action of heat, moisture, and carrier gas. The components then were resolved by temperature programmed gas chromatography (GC) on a 1 ft x 1/4 in. Porapak Q column. A second gas chromatographic method, a volatilization procedure, was included in the study for comparison as a measure of the concentrations of acetone or 2-propanol. Samples of oilseed meals and flours were analyzed by both methods. The rapid elution procedure proved to be a simple and effective means of detecting residual acetone or 2-propanol in the samples. The values were very similar to those obtained by the volatilization procedure.     

噻磺隆原药液相色谱分析

介绍以ｕｌｔｉａｓｐｈｅｒｓ－ＯＤＳ反相色谱柱,甲醇和醋酸钠－醋酸缓冲液为流动相的高效液相色谱系统,分析噻磺隆原药,经紫外检测器进行定量的方法。并对方法的线性关系、精密度、准确度进行了评估。     

Correction procedures for extra-column effects in dynamic column breakthrough experiments

Dynamic column breakthrough experiments, routinely used to complement adsorption and diffusion studies at the particle scale, constitute an important step in the development and verification of dynamic models for simulation of adsorption processes. Various parts of the experimental setup contribute to the retention time and band broadening of the experimental breakthrough curve. However, the effect of the extra-column contributions have to be properly accounted for in order to compare the experimental results with theoretical calculations. A common practice is to measure a blank response under the same flow rate, pressure and temperature conditions as the actual experiment by simply bypassing the adsorption column with a tube (or a connector) of negligible volume. This blank response is then subtracted point-by-point from the composite response (i.e., including the adsorption column) to account for extra-column contributions. The underlying assumption here is that blank and column responses are linearly additive, both in terms of mean residence time and band broadening. It is shown that this method of correction can, under certain operating conditions, lead to erroneous results. An alternative procedure based on linear regression is introduced and the improvements achieved by this method are illustrated using simulation examples.     

Isolation of sulphur heterocycles from petroleum- and coal-derived materials by ligand exchange chromatography

A rapid method for the isolation of sulphur heterocycles (PASH) from the aromatic fraction of complex mixtures is described, based on ligand exchange column chromatography using silica gel impregnated with palladium chloride. The application of the procedure to a coal liquid and petroleum heavy ends yielded sulphur fractions composed of PASH having two to six aromatic rings. The fractions were examined by capillary column gas chromatography with flame ionization and flame photometric detection, and by gas chromatography-mass spectrometry.