Showing papers on "Thin-layer chromatography published in 1991"

Phosphopeptide mapping and phosphoamino acid analysis by two-dimensional separation on thin-layer cellulose plates.

Abstract: Publisher Summary This chapter discusses the phosphopeptide mapping and phosphoamino acid analysis by two-dimensional separation on thin-layer cellulose plates. Peptide mapping is a powerful technique used to help determine peptide structure and composition of proteins. Peptide maps or fingerprints of proteolyzed proteins are usually obtained by resolution on either one-dimensional sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), reversed-phase high-performance liquid chromatography (HPLC), or by two-dimensional separation on thin-layer cellulose (TLC) plates. The most common applications of peptide mapping are (1) to compare proteins encoded by the same or related genes, (2) to prepare individual peptides for determining amino acid composition and sequence, and (3) to determine the precise location of amino acid residues that are posttranslationally modified by fatty acid acylation, glycosylation, methylation, acetylation, or phosphorylation.

Lifetime of neutral-carrier-based liquid membranes in aqueous samples and blood and the lipophilicity of membrane components.

Abstract: On the basis of previously reported correlations between the lipophilicity of membrane components, their partition coefficient between the membrane and the sample, and the lifetime of corresponding neutral-carrier-based sensors, the lipophilicities of ionophores and plasticizers in analytically relevant ion-selective electrodes, ISFETs, and optodes are analyzed and reported. Equations for the estimation of the lifetimes of liquid membranes in continuous-flow systems are presented, and the experimental determination of the lipophilicity values by thin-layer chromatography (TLC) is described. The required lipophilicities for the lifetimes of liquid membranes over 30 24-h days for different applications in aqueous solutions as well as in blood are presented. A comparison of the experimental results of lifetime measurements with calculated theoretical values is given. The experimental results of the determination of the lipophilicity by TLC are compared with the lipophilicities estimated on the basis of Hansch parameters.

Quantification of Three Cholesterol Oxidation Products in Raw Meat and Chicken

Abstract: Raw veal, beef, pork, and chicken muscle tissues were extracted by a modified dry column procedure in which silicic acid was incorporated in the trap of the column. This method separated cholesterol derivatives from the bulk of neutral lipids, phospholipids and cholesterol. Isolation of sterols by preparative thin layer chromatography followed by quantification by direct on-column capillary gas chromatography permitted measurement of 7-ketocholesterol, cholesterol 5α, 6α-epoxide, and cholesterol 5β 6β-epoxide at concentrations less than 1 ppm. All muscle tissues contained the three cholesterol products in measurable quantities. 7-Ketocholesterol constituted more than 50% of the oxidation products in all samples.

Separation of cholesterol, and fatty acylglycerols, acids and amides by thin-layer chromatography

Abstract: A rapid unidimensional thin-layer chromatographic (TLC) method for the separation of neutral lipids is described, using two sequential solvent systems of different polarity. Excellent separations of mono-, di- and triglycerides, fatty acids, fatty amides, and cholesterol are thereby achieved. Separation is accomplished at room temperature and requires 25 min.

Silica subsurface amine effect on the chemical stability and chromatographic properties of end-capped immobilized artificial membrane surfaces.

Abstract: The silica surface of immobilized artificial membranes containing phosphatidylcholine (IAM.PC) has approximately two aminopropyl groups per immobilized phosphatidylcholine molecule. Primary amines near the silica subsurface adsorb biomolecules and also decrease the chemical stability of IAM.PC surfaces. Consequently, subsurface amines were end-capped by several methods including silylating reagents, acetyl analogues, glycidol, methyl glycolate, short-chain anhydrides (3-6 carbons/anhydride chain), and long-chain anhydrides (10-12 carbons/anhydride chain). All end-capping reactions resulted in loss of the initially immobilized phosphatidylcholine molecule. However, the amount of PC loss during end capping was very low (for alkyl anhydride end-capping reactions) to very high (for silylation end-capping reactions). After end capping, IAM.PC showed increased chemical stability compared to non end-capped IAM.PC surfaces. The chemical stability of IAM packing material was monitored by phospholipid leaching from IAM surfaces exposed to organic and aqueous solvents using thin-layer chromatography, 1H NMR spectroscopy, infrared spectroscopy, and mass spectrometry. IAM.PC packing material end capped with long-chain anhydrides exhibited the greatest chemical stability, i.e., little or no detectable phospholipid leaching when challenged with aqueous and/or organic solvents. The chromatography of acidic and basic compounds on end-capped and non-end-capped IAM.PC surfaces was studied. Compared to non-end-capped IAM.PC HPLC columns, the chromatographic retention times of acidic compounds (deoxynucleotides) decreased after end capping. In contrast, the retention times of basic compounds (amphetamine analogues) increased on end-capped IAM.PC HPLC columns relative to non-end-capped IAM.PC HPLC columns. This indicates that these solutes have access to the silica subsurface amines during chromatography.

Isolation and purification of cell wall polysaccharide of Bacillus anthracis (Δ Sterne)

Abstract: A polysaccharide fraction was isolated form sodium-dodecyl-sulfate (SDS) treated cell walls of Bacillus anthracis (delta Sterne) by hydrofluoric acid (HF) hydrolysis and ethanolic precipitation. The polysaccharide fraction was subsequently purified by several washings with absolute ethanol. Purity of the isolated polysaccharide was tested using the anthrone assay and amino acid analyzer. The molecular mass of the polysaccharide fraction as determined by gel filtration chromatography was about 12000 Da. Preliminary analyses of the polysaccharide was done using thin layer chromatography and amino acid analyzer, and results obtained from these analyses were further confirmed by gas liquid chromatography and 13C-NMR spectroscopy. Results showed that the polysaccharide moiety contained galactose, N-acetylglucosamine, and N-acetylmannosamine in an approximate molar ratio of 3:2:1. This moiety was devoid of muramic acid, alanine, diaminopimelic acid, glutamic acid, and lipid, thus indicating that the isolated polysaccharide was of pure quality.

Some Separations of Black and Red Water-Soluble Fiber-Tip Pen Inks by Capillary Zone Electrophoresis and Thin-Layer Chromatography

Abstract: Capillary zone electrophoresis was tried for analyzing water-soluble fiber-tip pen inks from documents. The separation process for the compounds—most of them move as anions—is usually less than 10 min. Some examples of possible applications, also combined with thin-layer chromatography, are given.

Structural studies of gangliosides from the YAC-1 mouse lymphoma cell line by immunological detection and fast atom bombardment mass spectrometry.

Abstract: YAC-1 cells were propagated in bioreactors in 11 and 7.51 volumes. The cells were metabolically labelled withd-[1-14C]galactose andd-[1-14C]glucosamine. The ganglioside fraction, purified by DEAE-Sepharose and silica gel column chromatography, showed on thin layer chromatography four major bands with mobilities between GM1 and GD1a. Gangliosides, obtained by further purification steps including high performance liquid chromatography on silica gel 60 columns with a gradient system of isopropanol:hexane:water, and preparative high performance TLC were characterized by (1) immunostaining of corresponding asialogangliosides obtained by mild acid hydrolysis and neuraminidase treatment and (2) fast atom bombardment mass spectrometry of native and permethylated samples and methylation analysis of GM1b ganglioside. As well as small amounts of GM2 and GM1, the major gangliosides found in the complex mixture were GM1b and GalNAc-GM1b. The structural heterogeneity of these gangliosides was cased by (a) substitution of the ceramide moiety by fatty acids of different chain length and degree of unsaturation (C16:0, C24:0, C24:1) and (b) N-substitution of the sialic acid moieties with either acetyl or glycolyl groups. Disialogangliosides were detected only in low amounts and will be the subject of further investigation. A polyclonal chicken antiserum was raised against IVNeuAc-GgOse5Cer. The antiserum was highly specific for gangliosides (IVNeuAc and IVNeuGc) and asialogangliosides with a GgOse5Cer backbone. No cross-reaction with GM1b or GgOse4Cer was observed.

Modified ninhydrin spray reagent for the identification of amino acids on thin-layer chromatography plates

Abstract: Identification of amino acids is essential for the evaluation of protein structure and also for the determination of the presence of amino acids in natural products. D-Camphor-10-sulphonic acid–ninhydrin can produce various distinguishable colours when it reacts with amino acids, whereas ninhydrin itself produces the same purple colour with most of them. The detection limits for amino acids for the proposed spray reagent range between 0.4 and 2.0 µg, under cold conditions, and 0.2 and 1.0 µg, after heating.

High Performance Liquid Chromatography Determination of Chemical Preservatives in Yogurt

Abstract: Reverse phase HPLC was used to determine the preservatives methyl-, ethyl- and propyl-p-hydroxybenzoate and sorbic acid in aqueous solutions, using n-butyl-p-aminobenzoate as the internal standard. This method was applied to the analysis of preservatives in yogurt. the preservatives were previously identified by thin layer chromatography, and revealed at 254 nm.

Hydrogenation of soybean oil: a thin-layer chromatography and gas chromatography/matrix isolation/Fourier transform infrared study

Abstract: By use of GC/MI/FT-IR spectroscopy, the double-bond configurations of fatty acid methyl esters derived from hydrogenated soybean oil and margarine were determined from the positions of observed IR bands.

HPTLC separation of aromatic α-amino acid enantiomers on a new histidine-based stationary phase using ligand exchange

Abstract: A new chiral ligand exchange selector for hydrophobic stationary phase modification has been synthesized by selective alkylation of L-histidine at the pyrrolic nitrogen atom in its imidazolic ring. Its performance was then tested on RP-HPTLC plates treated with copper acetate. Significant selectivity towards aromatic amino acid enantiomers, was observed. Chromatographic retention data were compared to available thermodynamic complex formation parameters for the relevant model systems in aqueous solution. Stationary and mobile phase effects on retention were studied by using different RP-HPTLC plates and various binary aqueous solvent mixtures. Optimized separation conditions for aromatic amino acid sample class are given.

Detection, Isolation, and Identification of Truxillines in Illicit Cocaine by Means of Thin-Layer Chromatography and Mass Spectrometry

Abstract: By means of thin-layer chromatography, an unidentified alkaloidal fraction was observed in illicit cocaine. Because of its persisting presence, efforts were undertaken to isolate and identify this fraction. Various analytical techniques showed complex results, finally pointing to the possibility of isomerization of constituents of the fraction. A direct-probe mass spectrum showed a fragmentation pattern which could only fit a truxilline. When using thin-layer chromatography, at least five isomers could be observed. This is the first time truxillines have been observed, isolated, and identified by thin-layer chromatography.

Copper(II)-Phthalocyanine Sulfonyl-Aminopropyl Silica Gel for Separation of π-Electron Rich Compounds by High-Performance Liquid Chromatography

Abstract: 2c-Electron rich compounds such as polycyclic aromatic hydrocarbons have been of interest as medical drugs, mutagens, and pollutants. To separate such compounds from one another by HPLC, m-electron interaction between stationary phase and samples (ic-interaction) could be effective. Stationary phases have thus been investigated by use of the ic-interaction.3-5 In this research, our attentions have been fixed on Cu(II)phthalocyanine derivatives, one of which has been known to adsorb mutagens6 by the 2r-interaction. We tried to develop a new stationary phase: silica gel bound with Cu(II)-phthalocyanine derivatives (CuPCSs).

The Synthesis of New Xylosyloligosaccharides by Transxylosylation with Aspergillus niger β-Xylosidase

Abstract: The synthesis of xylosyloligosaccharides from β-(1→4)-xylobiose in the presence of d-mannose by transxylosylation with β-xylosidase from Aspergillus niger IFO 6662 was studied. At first, the transxylosylation products were separated by charcoal column chromatography in 5% ethanol elution into three peaks, P-1, P-2, and P-3. They were further separated on thin layer chromatography, and their three products, saccharides O-4, O-5, and O-N were purified by preparative paper chromatography. Saccharides O-4 and O-5 were identified as O-β-d-xylopyranosyl-(1→4)-d-mannopyranose and O-β-d-xylopyranosyl-(1→6)-d-mannopyranose, respectively, by measurement of the degree of polymerization, specific rotation, acid hydrolysis, and methylation analysis. By 1H-NMR spectroscopy in addition to these analyses, saccharide O-N was identified as O-β-d-xylopyranosyl-(1→1 )-β-d-xylopyranose, a new nonreducing xylobiose.

Determination of tricyclic antidepressant drugs in the presence of interfering substances

Abstract: Method and reagents for determining a compound of interest present in a test sample also containing one or more interfering compounds having substantially similar chemical structures, and otherwise analytically indistinguishable from each other, employing a pretreatment reagent capable of selectively modifying the chemical structure of one of the compounds without significantly modifying or altering the chemical structure of the other one of the compounds. The selective modification results in the modified compound having a chemical structure which is substantially dissimilar to the chemical structure of the other one of said compounds wherein the compounds are substantially distinguishable from each other to permit the analytical determination of one or the other of such compounds by immunoassay, high pressure liquid chromatography, and thin layer chromatography techniques, especially for the fluorescent polarization immunoassay determination of tricyclic antidepressant drugs in the presence of phenothiazines.

Studies on curcumin and curcuminoids. XIX: Evaluation of thin-layer chromatography as a method for quantitation of curcumin and curcuminoids

Abstract: ZusammenfassungVerschiedene Systeme zur dünnschichtchromatographischen Quantifizierung von Curcumin und Curcuminoiden werden diskutiert. Die stationäre Phase basierte auf Silicagel und einer mit Aminogruppen versehenen Phase. Dünnschichtchromatographie als alternative Methode zur Hochdruckflüssigchromatographie (HPLC) für die quantiative Bestimmung von Curcumaproben wird diskutiert.SummaryThe present paper evaluates TLC systems based on silica gel on amino-bonded stationary phases for quantification of curcumin und curcuminoids. TLC as an alternative method to HPLC for quantitation of Curcuma samples is discussed.

Quantitative analysis by thin-layer chromatography with secondary ion mass spectrometry

Abstract: A direct combination of thin-layer chromatography with secondary ion mass spectrometry (TLC/SIMS) provides a method for the quantitative analysis of thermally unstable compounds or compounds of low volatility such as nicergoline. The method is very simple and has excellent precision.

Combined use of normal and reversed phase thin layer chromatography in the screening for basic and quaternary drugs

Abstract: The combined use of normal and reversed phase thin layer chromatography in drug screening is evaluated by the mean list length method. A reversed phase system, involving RP-18 plates and aqueous hydrochloric acid - methanol as a mobile phase, is shown to be an effective complementary pair to basic medium-polar normal phase systems. With a set of 140 basic and quaternary drugs, a mean list length of 1.8 is obtained for a TLC/RPTLC pair. The combination is also applicable to hydrophilic drugs extracted as bis(2-ethyl-hexyl)phosphate ion-pairs.