Showing papers on "Thin-layer chromatography published in 1984"
TL;DR: In this article, the authors attempted to synthesize carbohydrate esters of fatty acids enzymatically in order to overcome the problems associated with the chemical processes for the synthesis of commercial sucrose esters.
Abstract: The authors attempted to synthesize carbohydrate esters of fatty acids enzymatically in order to overcome the problems associated with the chemical processes for the synthesis of commercial sucrose esters. The enzymes used were lipases from microorganisms belonging toRhyzopus, Enterbacterium, Aspergillus, Pseudomonas, Chromobacterium, Candida, Mucor andPenicillium. Fatty acids (stearic, oleic and linoleic) and carbohydrates (sucrose, glucose, fructose and sorbitol) used for the reaction were obtained from commercial sources. The enzyme reaction was performed by mixing the enzyme and the substrates in the buffer solution and incubating at 40 C; after freeze-drying the mixture, the products were extracted and subjected to thin layer chromatography (TLC) and high performance liquid chromatography (HPLC). It was observed by TLC and HPLC that carbohydrate esters of fatty acid were produced by the enzyme reaction, and their structures were confirmed by infra red (IR) and nuclear magnetic resonance (NMR) spectrometries. The lipase fromCandida cylindracea was the most enzyme active on the synthesis of carbohydrate esters. The optimum conditions for its activity were as follows: molar ratio of carbohydrate to fatty acid: 0.05mol/l : 0.2mol/l; amount of lipase: 4g/l; pH of the reaction mixture: 5.4 in phosphate buffer; reaction period: 72 hr.
132 citations
TL;DR: A sensitive enzyme-immunochemical staining method was developed for detection of N-glycolylneuraminic acid (NeuGc)-containing glycosphingolipids (GSLs) on silica gel thin-layer chromatography and can be applied easily to other glycolipid antigen systems.
Abstract: A sensitive enzyme-immunochemical staining method was developed for detection of N-glycolylneuraminic acid (NeuGc)-containing glycosphingolipids (GSLs) on silica gel thin-layer chromatography. The procedure consists of immune reaction among NeuGc-containing GSLs, affinity-purified chicken anti-NeuGc-LacCer and horseradish peroxidase-conjugated rabbit anti-chicken IgG, and the peroxidase reaction using 4-chloro-1-naphthol as a chromogenic substrate. Quantitative determination was achieved by direct densitometric scanning of the enzyme-immunostained spots on the chromatogram. As little as 0.5 pmol of NeuGc-LacCer, NeuGc-nLcOse4Cer, and NeuGc-nLcOse6Cer (0.64-1.0 ng) could be detected with a good signal-to-noise ratio. A semi-linear detector response was observed up to 50 pmol of each GSL. This procedure can be applied easily to other glycolipid antigen systems.
110 citations
TL;DR: A rapid method for the separation and quantitation of the major lipids of tissues and lipoproteins by automated high-performance thin-layer chromatography is presented and is particularly suitable for the rapid quantification of small amounts of lipid.
96 citations
TL;DR: In this paper, the effects and interaction of PL and TOC on soybean-oil stability were evaluated using the time in days of oil samples incubated at 110C to reach a peroxide value of 100 meq/kg, and the effect of the PL was not simply a matter of pro-oxidant metal inactivation, but rather appeared to extend the effectiveness of TOC in free-radical termination.
Abstract: The phospholipids (PL), phosphatidylcholine (PC) and phosphatidylethanolamine (PE) were purified from commercial soybean lecithin by silicic acid chromatography and preparative silica gel thin layer chromatography (TLC). Purified phosphatidylinositol (PI) was obtained commercially. Phosphatidic acid (PA) was made from PC by phospholipase D action and purified by preparative TLC. Commercial soybean tocopherols (TOC) were further purified in a florisil column. Combinations of PL and TOC were added to commercially refined, unhydrogenated soybean oil to determine the effects and interaction of PL and TOC on soybean-oil stability. Oil stability was determined by measuring the time in days of oil samples incubated at 110C to reach a peroxide value of 100 meq/kg. Additions of TOC and all PL except PA increased the stability of the oil. PI and PE appear to be more effective than PC in increasing oil stability. The effect of the PL was not simply a matter of pro-oxidant metal inactivation, but rather appeared to extend the effectiveness of the TOC in free-radical termination.
96 citations
Patent•
27 Jul 1984
TL;DR: In this paper, a highly selective bonded phase material useful to separate a wide variety of organic and inorganic substances by thin layer chromatography (TLC), liquid chromatography, or high performance Liquid Chromatography (HPLC) is produced by bonding a cyclodextrin to a silica gel.
Abstract: A highly selective bonded phase material useful to separate a wide variety of organic and inorganic substances by thin layer chromatography (TLC), liquid chromatography (LC) or high performance liquid chromatography (HPLC) is produced by bonding a cyclodextrin to a silica gel by means of a specific silane linkage. The preparation of such materials and their uses are described.
89 citations
75 citations
TL;DR: A method for the quantitation of small amounts of phospholipids derived from biological sources is described, determined by mineralization followed by the estimation of liberated phosphate by means of malachite green.
61 citations
TL;DR: The data show that at the molar concentration usually employed in biological studies with these compounds, one can assume that they will be present as monomolecular species, and it seems unlikely that the widely diverse biological activities of these compounds can be explained by this physical parameter.
55 citations
TL;DR: A process for the separation of enantiomers by TLC was described in this article, where reversed-phase plates, pre-treated with a copper II complex of N,N-di-n-propyl-L-alanine, were used to separate all the dansyl protein amino acids, except proline, each to its D and L enantiomer.
53 citations
TL;DR: In this article, aqueous solutions N,N-dialkyl-N′-benzoylthioureas form neutral chelates with a great number of metal ions; these chelated can be extracted with CHCl3 and separated by chromatography.
Abstract: SummaryIn aqueous solutions N,N-dialkyl-N′-benzoylthioureas form neutral chelates with a great number of metal ions; these chelates can be extracted with CHCl3 and separated by chromatography. The lower-valent platinum-group metal ions as pronounced class (b)-acceptors form very stable chelates. Silicagel 60 as stationary phase and pure solvents of medium polarity like CHCl3, benzene, toluene or xylene as mobile phase are used for separation by TLC. In this way 3 to 4 metals can be determined on a distance of 3 to 4 cm in one step. The limits of detection of the metals are 0.5 to 10 ng (UV-remission measurement using HPTLC-plates).ZusammenfassungN,N-Dialkyl-N′-benzoylthioharnstoffe bilden in wäßriger Lösung mit einer größeren Zahl von Metallionen Neutralchelate, die sich in CHCl3 extrahieren und chromatographisch trennen lassen. Einen besonderen Schwerpunkt stellen dabei die Platinmetalle dar, deren niederwertige Metallionen als typische (b)-Akzeptoren besonders stabile Chelate bilden. Für die dünnschicht-chromatographische Trennung der Chelate wird Kieselgel 60 verwendet. Als mobile Phase dienen Einkomponentenlaufmittel mittlerer Polarität wie CHCl3, Benzol, Toluol oder Xylol. Auf diese Weise lassen sich auf 3–4 cm Laufstrecke in einem Arbeitsschritt 3 bis 4 Metalle bestimmen. Die Nachweisgrenzen der Metalle liegen zwischen 0,5 und 10 ng (UV-Remissionsmessung auf HPTLC-Platten).
52 citations
TL;DR: A simple, rapid, and solvent-efficient method for determining aflatoxins in corn and peanut butter is described and aflatoxin B1 from corn was 82%, and the limit of determination was 2 ng/g.
Abstract: A simple, rapid, and solvent-efficient method for determining aflatoxins in corn and peanut butter is described. Aflatoxins B1, B2, G1, and G2 were extracted from 50 g sample with 200 mL methanol-water (85 + 15). A portion of the extract was diluted with 10% NaCl solution to a final concentration of 50% methanol, and then defatted with hexane. The aflatoxins were partitioned into chloroform. The chloroform solution was evaporated, and the residue was placed on a 0.5 g disposable silica gel column. The column was washed with 3 mL each of hexane, ethyl ether, and methylene chloride. Aflatoxins were eluted with 6 mL chloroform-acetone (9 + 1). The solvent was removed by evaporation on a steam bath, and the aflatoxins were determined using thin layer chromatography (TLC) with silica gel plates and a chloroform-acetone (9 + 1) developing solvent. Overall average recovery of aflatoxin B1 from corn was 82%, and the limit of determination was 2 ng/g. For mass spectrometric (MS) confirmation, aflatoxin B1 in the extract from 3 g sample (20 ng/g) was purified by TLC and applied by direct on-column injection at 40 degrees C into a 6 m fused silica capillary gas chromatographic column. The column was connected directly to the ion source. After injection, the temperature was rapidly raised to 250 degrees C, and the purified extract was analyzed by negative ion chemical ionization MS.
TL;DR: In this article, three analytical methods were used to determine the concentration of ditallow dimethyl ammonium chloride (DTDMAC), a cationic surfactant in river water, sewage influent and sewage effluent.
TL;DR: In this article, the lipophilicity of aniline derivatives was determined by reversed-phase thin-layer chromatography using methanol, acetone and acetonitrile as the organic phase.
Abstract: The lipophilicity of aniline and 36 ring-substituted aniline derivatives was determined by reversed-phase thin-layer chromatography using methanol, acetone and acetonitrile as the organic phase. The RM value of each compound linearly decreased with increasing concentration of the organic solvent, Acetonitrile showed the highest and methanol the lowest solvent strength, however, the difference between the solvent strength of methanol and acetone was negligible. The site of the substitution considerably influenced the lipophilicity particularly in the case of −NO2 groups. Good correlation was found between the RM value extrapolated to zero organic phase concentration and the partition coefficient between n-octanol:water. The change in the RM value caused by a 1% increase of the organic phase concentration also correlated with the partition coefficient, however, it was of secondary importance. The lipophilicity parameters determined by reversed-phase thin-layer chromatography correlated to a lesser extent with the calculated lipophilicity values of aniline derivatives.
TL;DR: In this paper, a radioimmunoassay for abscisic acid (ABA) in the 004 pmole to 48 pmoles range was developed, which utilizes an iodinated derivative of (+) ABA-Gly Tyr as a tracer.
TL;DR: In this paper, the authors used both indirect and direct methods for the detection of epsilon(gamma-glutamyl) lysine crosslinks, which is not only necessary for establishing the importance of the dipeptide as a post-translational modification of proteins, but also provides information as to the importance the transglutaminase enzyme in a biological system.
Abstract: Detection of epsilon(gamma-glutamyl) lysine crosslinks is not only necessary for establishing the importance of the dipeptide as a post-translational modification of proteins, but provides information as to the importance of the transglutaminase enzyme in a biological system. The crosslink may be detected using both indirect and direct methodology. Indirect methods for its detection include measurement of 'masked lysines' within a protein, detection of polymer formation by gel-electrophoresis and the inhibition of crosslinking by the incorporation of small molecular weight amines into the substrate protein. Direct methods for the detection of epsilon(gamma-glutamyl) lysine require the actual isolation of the dipeptide following its release from the sample protein by exhaustive proteolytic digestion. Separation of the dipeptide from other components of the digest may be achieved by either ion-exchange chromatography or gel filtration and its qualitative identification achieved by techniques such as paper-electrophoresis or thin layer chromatography. Quantitative estimation of epsilon(gamma-glutamyl) lysine normally involves its further separation by ion-exchange chromatography and its post-column detection following derivatisation with ninhydrin. More recent techniques include pre-column derivatisation of the dipeptide with fluorogenic reagents such as sigma-pthalaldehyde and separation by reverse phase HPLC. With the recent advances in liquid chromatography resulting in the improved resolution of amino acids, increased sensitivity, rapid analysis times, and small sample sizes, it appears likely that direct quantitation of epsilon(gamma-glutamyl) lysine will be the preferred method for the future.
TL;DR: A combination of thin-layer and gas chromatography has been shown to be suitable for the analysis, characterisation and discrimination of the small quantities of lipsticks which may be encountered in forensic casework.
TL;DR: In this paper, unimpregnated cellulose layers proved to be suitable for the determination of the lipophilic character of 14 3,5-dinitro benzoic acid esters under reversed phase, thin-layer chromatographic conditions.
Abstract: Unimpregnated cellulose layers proved to be suitable for the determination of the lipophilic character of 14 3,5-dinitro benzoic acid esters under reversed-phase, thin-layer chromatographic conditions. Lipophilic characters measured on unimpregnated cellulose layers correlated well with similar values determined on impregnated silica and on impregnated alumina. Minor differences in retention of the three types of layers were observed.
TL;DR: Nine phorbol diesters and monoesters were isolated from a commercial sample of croton oil and characterized spectroscopically, showing short-chain ester functionalities, with 4-deoxy-4α-phorbol-13-acetate being new compounds.
Abstract: Five phorbol diesters, three 4-deoxy-4α-phorbol diesters, two phorbol monoesters, and one 4-deoxy-4α-phorbol monoester were isolated from a commercial sample of croton oil and characterized spectroscopically. Their purification was achieved using combinations of droplet countercurrent chromatography, low-pressure column chromatography over phase-bonded silica gel, and preparative thin layer chromatography. All of these isolates were shown to possess short-chain ester functionalities, with 12-O-tiglylphorbol-13-isobutyrate, 12-O-(2-methyl)butyrylphorbol-13-isobutyrate, 12-O-(2-methyl)butyrylphorbol-13-acetate, 12-O-tiglyl-4-deoxy-4α-phorbol-13-isobutyrate, 12-O-tiglyl-4-deoxy-4α-phorbol-13-acetate, 12-O-(2-methyl)butyryl-4-deoxy-4α-phorbol-13-acetate, phorbol-12-tiglate and 4-deoxy-4α-phorbol-13-acetate being new compounds.
TL;DR: In this paper, the authors show that the insufficient resolution in discrete regions of the HPLC profile of such mixtures is caused by both intrinsic structural properties within each phospholipid class ( e.g., heterogeneity in aliphatic residues), which cause severe expansion of the eluted peaks, and by changes related to column performance.
TL;DR: In this article, thin-layer chromatography (TLC) was applied to the chemical class fractionation of shale oil and the principal compound types resolved included n-alkanes, alkenes, mono-, hydro-, di-, and polyaromatics, nitriles and ketones, hydroxyl aromatic hydrocarbons, and nitrogen heterocyctes.
Abstract: Thin-layer chromatography (TLC) has been applied to the chemical class fractionation of shale oil. The chromatographic procedure gives rapid and reproducible separation of the oil into 14 fractions, without requiring prior extraction of asphaltenes, acids, or bases. The oil was adsorbed on silica-coated TLC plates and eluted with n-pentane and n-pentane/diethyl ether to separate the nonpolar and polar components, respectively. The principal compound types resolved included n-alkanes, alkenes, mono-, hydro-, di-, and polyaromatics, nitriles and ketones, hydroxyl aromatic hydrocarbons, and nitrogen heterocyctes. Compound identification was by gas chromatography/mass spectroscopy supplemented by ir spectrometry. The method significantly decreases the analysis time required for chemical class fractionation. 33 references, 4 figures, 1 table.
TL;DR: In this paper, the detectable luminescence of twelve dansy1 amino acids and four polycyclic aromatic hydrocarbons (PAH's) spotted on five common TLC stationary phases was evaluated.
Abstract: The detectable luminescence of twelve dansy1 amino acids and four polycyclic aromatic hydrocarbons (PAH's) spotted on five common TLC stationary phases was evaluated. The detectable luminescence varied appreciable for compounds associated with different stationary phases. The use of surfactant and cyclodextrin spray reagents caused luminescence enhancements on some stationary phases but not others. The reagents did not affect all compounds to the same degree indicating that qualitative information could be obtained in some cases. The largest luminescence increase for a compound spotted on silica gel was for pyrene (i.e., 47-fold) sprayed with sodium cholate. The degree to which the plates were dried also affected the luminescence intensity. Possible reasons for the observed effects are discussed.
TL;DR: Inspection of the TLC pattern of the neutral lipid fraction of bovine thyroid reveals, in addition to cholesteryl esters and dolichyl fatty acid esters, the presence of a not yet identified compound in the most apolar lipid region.
TL;DR: In this paper, two-dimensional thin-layer chromatography was used to analyze methanolysates for the presence of the methyl esters of mycolic acids which are characteristic high molecular weight 3-hydroxy-2-alkyl fatty acids.
TL;DR: In this article, the use of over-pressurized thin-layer chromatography in ion-pair TLC has been studied and the most important aspect when a reversed-phase TLC system is to be used is to apply a suitable procedure for pre-treatment of the sorbent.
TL;DR: The metabolism of norgestimate (ORF-10131; 14C-d-13-ethyl-17-acetoxy-18,19-dinor-17 alpha-pregn-4-en-20- yn -3-oxime) was studied in humans and five urinary metabolites were identified by combined gas-liquid chromatography/mass spectrometry.
TL;DR: Thin-layer chromatography on silica gel 60 plates in the solvent N,N-dimethylformamide/methanol/ethylene glycol/glacial acetic acid/1-chlorobutane/chloroform separates porphyrin carboxylic acids by the number of free carboxyl groups.
TL;DR: The described procedures are satisfactory for confirming mycotoxins present in standards, artificially contaminated grain samples (barley, corn, oat, rye, and wheat), and extracts from both fungal cultures and naturally contaminatedgrain samples.
Abstract: Published tests have been improved and a new procedure is described for chemical confirmation of mycotoxins directly on thin layer plates. After extraction and preliminary cleanup chromatography with n-hexane or chloroform, the mycotoxins ochratoxin A, citrinin, penicillic acid, sterigmatocystin, and zearalenone were easily separated by thin layer chromatography (TLC) using toluene-ethyl acetate-90% formic acid (6 + 3 + 1) developing solvent. In chemical confirmatory methods, the developed chromatogram was exposed to vapors of pyridine, acetic anhydride, or a mixture, or the mycotoxins were over-spotted. With this treatment, ochratoxin A, citrinin, penicillic acid, and zearalenone were converted to new fluorescent compounds, and observed under 365 nm light after re-chromatography with the same developing solvent. Sterigmatocystin was confirmed chemically using TLC plates impregnated with 0.6N H2SO4 or 10% oxalic acid in methanol. The described procedures are satisfactory for confirming mycotoxins present in standards, artificially contaminated grain samples (barley, corn, oat, rye, and wheat), and extracts from both fungal cultures and naturally contaminated grain samples.