Thin layer chromatographic procedure for class separation of plant neutral lipids

A thin layer chromatographic method has been developed for the class separation of plant neutral lipids. Utilizing a two-step development in one dimension, lipid mixtures are separated into hydrocarbon waxes, steryl esters, methyl esters, triglycerides, fatty acids, diglycerides, sterols, and monoglycerides. The method may be employed for either qualitative or preparative purposes.     

Conditions and techniques for thin layer chromatography of aflatoxins

Satisfactory resolution of the four common aflatoxins, B₁, B₂, G₁ and G₂, on thin layer chromatograms has been a recurring problem. The most frequently observed cause of poor resolution and tailing of spots in the chromatograms was the variable properties of the commercial silica gel-calcium sulfate adsorbent preparations. Variations in quality were observed even from one container to the next within single lots produced by individual manufacturers. Other variables which affected the chromatography to some degree included adsorbent particle size, concentration and nature of the calcium sulfate binder, silica gel layer thickness and moisture content, vapor phase composition in the developing chamber and the solvent used for development.     

Gas liquid and thin layer chromatographic analysis of 12-aminostearic acid

Products from the reductive amination of 12-ketostearic acid to 12-aminostearic acid have been monitored by gas liquid chromatography (GLC) and thin layer chromatography (TLC). The nonvolatile amino acid was analyzed by TLC, but its trifluoroacetylated methyl ester was analyzed by TLC and GLC. Conditions for obtaining high conversions of the amino acid to this derivative are described. The derivative was quantitated by GLC using methyl 12-ketostearate as an internal standard. Various developing solvents, types of TLC plates, and visualization spray reagents were examined and compared for efficiency and convenience regarding the TLC separations. Satisfactory TLC systems were developed for crude reaction mixtures containing 12-aminostearic acid and these same mixtures, which were trifluoroacetylated. The influence of water in the developing solvent on the ionic forms of the amino acid is discussed. Presented at AOCS-AACC Joint Meeting, Washington, D.C., April 1968.     

Application of silica gel-sintered plate to thin layer lipid chromatographic analysis

The merits and disadvantages of using the silica gel-sintered plate for lipid chromatographic analysis were investigated in detail. The commercially available sintered plate could be used repeatedly, employing the reconditioning procedure which involved chromic-sulfuric acid treatment and subsequent activation. The reconditioned sintered plate has now been used successfully 20 times, for lipid analysis without any deterioration of the excellent resolution power for complex lipid mixtures for all the solvent systems. Since the sintered plate is sturdy, the chromatogplate could be immersed directly in the liquid reaction mixture, so that spots on the chromatogram could be seen and impregnated plates prepared simply. The sintered plate was found to be much more economical than the silica gel-coated plate. Presented in part at the Japan Oil Chemists' Society 20th Annual Meeting, Tokyo, November 1972 The following abbreviations are used in this paper: TLC, thin layer chromatography; PA, phosphatidic acid; PS, phosphatidylserine; PC, phosphatidylcholine; LPC, lysophosphatidylcholine; PI, phosphatidylinositol; SPM, sphingomyelin; PE, phosphatidylethanolamine; PG, phosphatidylglycerol; CL, cardiolipin; CMH, ceramide-monohexoside; CDH, ceramide-dihexoside; CTH, ceramide-trihexoside; NL, neutral lipid.     

Thin layer chromatography/flame ionization analysis of transesterified vegetable oils

A quantitative method was developed for analyzing mixtures containing fatty esters and tri- (TG), di- (DG) and monoglycerides (MG) obtained by the transesterification of vegetable oils. Analyses were performed by thin layer chromatography (TLC)/flame ionization detection (FID) with an Iatroscan TH-10 instrument. Stearyl alcohol served as an internal standard. From plots of area and weight ratios of methyl linoleate and tri-, di- and monolinolein, linear equations were developed from which response factors were calculated. Hydrogen flow rate and developing solvent strongly influenced resolution and baseline stability. Variations in scan speed affected completeness of burning and response factors, but not measured composition. Sample weight also affected response factors but not measured composition. A computerized procedure for data analysis was developed so that 30 samples can be completed in 2–3 hr. Relative standard deviations were 1–2% for major components in the 90–100% range and 6–83% for minor components in the 1–2% range. Presented at the AOCS meeting, Chicago, May 1983. Biometrician, North Central Region, Agricultural Research Service, U.S. Department of Agriculture, stationed at the Northern Regional Research Center, Peoria, Illinois 61604.     

Thin layer chromatography and image analysis to detect glycerol in biodiesel

Glycerol is a by-product of biodiesel production and is also considered a contaminant in the final product. Current US and EU standards place limits on the permissible levels of free glycerol and bound (unconverted) mono, di and triglycerides in biodiesel, which can be quantified using gas or high pressure liquid chromatography.We report a method based on thin layer chromatography that can be effectively used to determine the presence of glycerol in biodiesel. Visual and machine (image analysis) detection limits of 0.1% and 0.2% v/v of free glycerol, respectively, were established using this procedure. In conjunction with a suitable sample enrichment procedure, this procedure could provide a cost effective alternative to glycerol detection.     

Extraction partition and column chromatographic separation of aflatoxins B1 and M1

Extraction, partition and chromatographic elution characteristics of aflatoxin were studied. The novel use of aqueous dimethylsulfoxide or aqueous dimethylformamide for extraction from agricultural products was tested and found effective. Partition studies suggest advantages in analytical work of using solvent pairs in which benzene rather than (the usually employed) chloroform is used to transfer aflatoxin B₁ from primary extracts (aqueous phases). Tests of elution characteristics of aflatoxins B₁ and M₁ on silica gel columns with different developing solvents provided a basis for a procedure in which aflatoxins B₁ and M₁ of a test sample are recovered in separate eluates in which substances which interfere with TLC separation are minimized. Presented at the AOCS Spring Meeting, San Francisco, April 1969. W. Utiliz. Res. Dev. Div., ARS, USDA.     

Densitometric equipment for rapid quantitation of aflatoxins on thin layer chromatograms 1

A densitometric instrument (Spotmeter) has been designed for rapid measurement of aflatoxin on thin layer chromatographic plates. The Spotmeter measures the total amount of fluorescence of the aflatoxin spot and thus eliminates the need for scanning mecha-nisms, plotters and integrators incorporated into most commercially available densitometers used for aflatoxin analyses. In comparison with a Schoeffel SD 3000 Spectrodensitometer, the Spotmeter was more accurate in one test and at least equally accurate in another test. The Spotmeter made measurements in 1/4 the time required for the Spectrodensitometer and would cost about 1/6 as much as commercially available densitometers suitable for aflatoxin analyses. 1 Paper Number 6203 of the Journal Series of the North Carolina Agricultural Research Service, Raleigh, NC.     

Thin layer solar drying characteristics of silkworm pupae

Thin layer solar drying experiments of silkworm pupae using a solar tunnel dryer were conducted under the tropical weather conditions of Mahasarakham, Thailand. The dryer consisted of a transparent glass covered flat-plate collector and a drying tunnel connected in series to supply hot air directly into the drying tunnel using a blower. During the experiments, silkworm pupae were dried to the final moisture content of 0.15 kg water kg^?1 dry matter from 4.37 kg water kg^?1 dry matter in 373 min at the corresponding air flow rate of 0.32 kg s^?1. Ten different thin layer drying models were compared according to their coefficient of determination to estimate drying curves. The Midilli–Kucuk model precisely represents the solar tunnel drying behavior with the coefficient of determination (R²) of 0.9982. The maximum drying rate and effective moisture diffusivity were 0.6723 kg water kg^?1 dry matter h^?1 and 2.7696 × 10^?10 m² s^?1, respectively, on the drying air flow rate of 0.32 kg s^?1. A quality assessment shows that the lipid content of the dried silkworm pupae was not affected by the solar tunnel dryer. A slight decrease of polyunsaturated fatty acid (PUFA) was observed.     

无患子皂甙在不同展开体系中的薄层色谱行为

以三氯化锑为显色剂,在不同展开体系中,对无患子假种皮的不同溶剂提取物进行薄层色谱分析,建立快速有效的无患子皂甙薄层色谱分析方法。结果显示,三氯甲烷展开体系的展开效果不太理想;正丁醇展开体系有利于大极性的皂甙的展开、分离,但是不适合于小极性的皂甙的分离;苯展开体系对小极性皂甙具有良好的分离效果,但不适合于大极性皂甙的展开。薄层色谱分析操作简便,适合于不同极性的无患子皂甙的快速分析检测。     

Thin layer and anion exchange chromatography of soybean saponins

Twenty-two solvent systems were evaluated for TLC of soybean saponins on silica gel. A maximum of four fractions separated by single development with the different solvents. Six successive developments with chloroformmethanol-water (65:25:4) separated soybean saponins into 10 or more fractions. Column chromatography of soybean saponins on an anion exchange resin with a linear gradient of acetic acid yielded seven fractions. Multiple development TLC of the saponins separated by column chromatography showed that a definite fractionation occurred. Several column chromatographic fractions contained components with identical TLC R_f values, but the components were clearly different on the basis of colors detected with sulfuric acid and on the basis of their elution positions from the ion exchange resin. Soybean saponins are more complex mixtures than previously recognized but can be fractionated by chromatography on thin layer plates and anion exchange resins. No. Utiliz. Res. Dev. Div., ARS, USDA.     

Thin layer drying kinetics of Gundelia tournefortii L.

The literature surveyed revealed that the drying kinetics of Gundelia tournefortii has not been investigated. In this study, mathematical modeling of the thin layer drying kinetics of G. tournefortii is investigated for both the microwave and open sun drying conditions. Five different microwave power levels ranging from 90 to 800 W were used for the microwave drying. Solar radiation for the open sun drying varied from 350 to 1100 W/m². Drying took place in the falling rate period. Increasing the microwave power caused a significant decrease in drying time. The experimental moisture loss data were fitted to the 14 thin layer drying models. Among the models proposed, the Midilli model precisely represented the microwave drying behavior of G. tournefortii with the coefficient of determination higher than 0.996 and mean square of deviation (χ²), root mean square error (RMSE) and mean bias error (MBE) lower than 1.82 × 10^?4, 12 × 10^?3 and 1.4 × 10^?4, respectively for all the microwave drying conditions studied. Values of drying constant (k) were in the range of 0.0098–0.2943 min^?1 and the effective moisture diffusivities (D_eff) of G. tournefortii ranged from 5.5 × 10^?8 to 3.5 × 10^?7 m²/s. The values of k and D_eff increased with the increase of microwave power level. The logarithmic model was found to best describe the open sun drying kinetics of G. tournefortii. The effective diffusivity of G. tournefortii under the sun drying condition was determined as 2.48 × 10^?10 m²/s.     

Two dimensional thin layer chromatographic separation of polar lipids and determination of phospholipids by phosphorus analysis of spots

Separation of polar lipids by two-dimensional thin layer chromatography providing resolution of all the lipid classes commonly encountered in animal cells and a sensitive, rapid, reproducible procedure for determination of phospholipids by phosphorus analysis of spots are described. Values obtained for brain and mitochondrial inner membrane phospholipids are presented.     

Thin layer drying kinetics of by-products from olive oil processing

The thin-layer behavior of by-products from olive oil production was determined in a solar dryer in passive and active operation modes for a temperature range of 20-50 °C. The increase in the air temperature reduced the drying time of olive pomace, sludge and olive mill wastewater. Moisture ratio was analyzed to obtain effective diffusivity values, varying in the oil mill by-products from 9.136 × 10(-11) to 1.406 × 10(-9) m(2)/s in forced convection (m(a) = 0.22 kg/s), and from 9.296 × 10(-11) to 6.277 × 10(-10) m(2)/s in natural convection (m(a) = 0.042 kg/s). Diffusivity values at each temperature were obtained using the Fick's diffusion model and, regardless of the convection, they increased with the air temperature. The temperature dependence on the effective diffusivity was determined by an Arrhenius type relationship. The activation energies were found to be 38.64 kJ/mol, 30.44 kJ/mol and 47.64 kJ/mol for the olive pomace, the sludge and the olive mill wastewater in active mode, respectively, and 91.35 kJ/mol, 14.04 kJ/mol and 77.15 kJ/mol in natural mode, in that order.     

Changes in physicochemical properties of active carbon within a grain

Commercial active carbons were subjected to abrasion in a spouted bed and as a result, active carbons, with external layers removed to different degrees, were obtained. For active carbons so obtained, physicochemical properties were determined from densimetric and adsorption investigation.It was found that radial changes in the properties of active carbons resulted from the nature of the activation reaction.It seems that the method of working by abrasion in spouted beds can also be used for investigating other processes taking place in fluid—solid system.     

Gas-liquid chromatographic analysis of mono-and diglycerides

A method is described for the quantitative analysis of mono- and diglycerides by GLC as their trimethylsilyl derivatives. Glyceryl mono and di-esters of myristic, palmitic, stearic, and oleic acids are separated by GLC on stainless steel columns, packed with 3% JXR on Gas Chrom Q. Relative response factors for monoglycerides and diglycerides have been calculated. Analyses of control and commercial mixtures with recoveries of 96 to 101% are reported.     

Pyrolysis gas chromatographic analysis of polyacrylonitrile

Pyrolysis gas chromatographic analysis of polyacrylonitrile under an inert atmosphere was made in a temperature region of 500–900°C. It was confirmed that the main degradation products are various kinds of lower nitriles that include CH₂CHCN, CH₃CN, and HCN. In addition, lower hydrocarbons such as CH₄ and C₂H₄, which are related to secondary decomposition, were detected. Various thermo‐analytical data were obtained, including those concerning the relation between retention time and the polarity of nitriles, and the dependence of the products' limiting yield on pyrolysis temperature. Based on the above results, specific applications of the pyrolysis gas chromatographic analysis and the utility of this procedure in the study of thermal degradation of polyacrylonitrile are described. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 79: 473–478, 2001     

Gas-liquid chromatographic analysis of lactoylated monoglycerides

This paper describes a method for analyzing gas-liquid chromatograms of silylated monoglycerides (1) and lactoylated monoglycerides. A simple method for lactoylating a monoglyceride for the determination of the products formed is also revealed. Resolution of glycerides containing as many as five lactoyl groups is obtained. Presented at the AOCS Meeting, Philadelphia, Pa., October 1966.     

Thin layer drying kinetics,characteristics and modeling of plaster of paris

Drying behavior of thin slabs of plaster of paris was investigated in microwave, convective and microwave assisted convective drier. The process parameters involved in the study include the microwave output power, air temperature used for drying, the initial moisture content of the sample, thickness and geometry of the sample. A typical drying profile, with no constant rate period followed by a falling rate period was obtained for all the three methodologies used. The mechanism of moisture movement within the sample during the falling period, as expressed by effective moisture diffusivity, was between 1.166 × 10⁻⁸ and 2.6927 × 10⁻⁸ (m² s⁻¹) for the least microwave output power of 180 W. The specific energy consumption and the drying efficiency involved in the microwave process, estimated from the energy supplied to the drier and the total time was found to be 0.4557 MJ kg⁻¹ and 82.56% for a sample thickness of 0.013 m. The microstructure of the fractured surfaces and qualitative phase analysis of microwave activated plaster of paris were extensively investigated by Scanning Electron Microscopy, Fourier Transform Infra-Red spectroscopy and X-Ray Diffraction techniques. The experimental moisture loss data with time was fitted to nine semiempirical thin layer equations. The suitability of the models was validated by comparing it with the predicted moisture ratio for any given set of operating conditions. The statistical analyses of the available literature correlations, for their applicability to the data of the present study showed greater deviation attributing their restricted range of applicability of individual correlations. As a result, a third order polynomial equation was developed from this study.     

Influence of trichloracetic acid-phosphotungstic acid on the thin layer chromatographic mobility of gangliosides

Trichloroacetic acid (TCA)-phosphotungstic acid (PTA) precipitation has been used as a faster procedure than dialysis for the isolation of gangliosides, but the TCA-PTA treatment causes striking abnormalities in the thin layer chromatographic mobilities of the gangliosides. However, a normal chromatographic pattern can be restored by treating the precipitated gangliosides with the tetrasodium salt of ethylenediamine tetraacetic acid followed by dialysis. Hence, TCA-PTA treatment does not appear to cause artifacts or hydrolysis of the gangliosides.