Showing papers on "Thin-layer chromatography published in 1999"
TL;DR: It is suggested that sterol composition may be more useful for the biochemical classification of these cnidarians than fatty acid composition.
Abstract: A survey of lipid composition was made for 15 cnidarians from Okinawa, Japan. Eleven zooxanthellate scleractinian corals, an azooxanthellate scleractinian coral Tubastrea sp., a soft coral Lobophytum crassum, a hydroid coral Millepora murrayi and a sea anemone Boloceroides sp. were examined to elucidate the total lipid content, fatty acid composition for each lipid class and sterol composition. All specimens contained monoalkyldiacylglycerol which migrated between the triacylglycerols and esters on thin layer chromatography (TLC). Analysis by high performance thin layer chromatography (HPTLC) and Gas chromatography-mass spectrometry (GC-MS) revealed that these cnidarians were rich in wax ester and triacylglycerol, and that palmitic acid (16:0) was the most abundant fatty acid component of these lipid classes, followed by stearic (18:0) and oleic (18:1, n-9) acid in order of concentration. Of 11 sterols separated, four sterols were identified. It is suggested that sterol composition may be more useful for the biochemical classification of these cnidarians than fatty acid composition.
138 citations
TL;DR: The assay combines the isolation and separation of curcuminoids on silica gel 60F254 high performance thin layer chromatographic plates, followed by scanning of the spots at 366 nm using a UV detection mode.
Abstract: A rapid and simple high performance thin layer chromatographic method has been developed for the simultaneous quantitation of pharmacologically important diaryl heptanoids curcumin, demethoxy curcumin, and bis-demethoxy curcumin in Curcuma longa and C. amada. The assay combines the isolation and separation of curcuminoids on silica gel 60F254 high performance thin layer chromatographic plates, followed by scanning of the spots at 366 nm using a UV detection mode.
133 citations
TL;DR: In this article, thin-layer chromatography and high-performance liquid chromatography were used for qualitative and quantitative analysis of phenolic acids in Ginkgo biloba leaves, and the amounts of both free and bound phenolic acid were determined within the whole vegetative period.
Abstract: In this paper, thin-layer chromatography and high-performance liquid chromatography for the qualitative and quantitative analysis of phenolic acids in Ginkgo biloba L. leaves are described. The amounts of both free and bound phenolic acids were determined within the whole vegetative period. For this purpose, a special extraction procedure, comprising acid and alkaline hydrolyses, was used. The described method allowed us to identify and estimate the concentration levels of eight phenolic acids: protocatechuic, para-hydroxybenzoic, vanillic, caffeic, isovanillic, para-coumaric, ferulic, and sinapic. Depending on the part of the plant vegetation, significant differences in the content of the compounds examined were observed and discussed. The elaborated method could be used in studies on the seasonal distribution of phenolic acids in plant material.
95 citations
75 citations
TL;DR: TLC based on MIPs could succeed the direct separation of enantiomers of adrenergic drugs as a method of separation and offers a rapid, sensitive and reliable method for quality control of optically active compounds.
59 citations
TL;DR: The proposed method enables rapid determination of enantiomers and screening of large numbers for optical purity of adrenergic drugs and indicates the stereoselectivity of the MIPs with the former isomers.
Abstract: Thin-layer chromatography (TLC) based on molecularly imprinted polymers (MIPs) of α-agonists as chiral stationary phases was applied to the determination of enantiomers of various adrenergic drugs including α- and β-agonists and β-antagonists (β-blockers). In this study, three MIPs imprinted with (+)-ephedrine, (+)-pseudoephedrine and (+)-norephedrine plus a non-imprinted polymer (non-MIP) were prepared, processed and coated on a glass support as thin layers. Then enantiomeric determination of adrenergic drugs was carried out by development of their racemates on the TLC plates, using established conditions. From the results, the racemates of the compounds used as print molecules were well separated into two isomers on the MIP-plates, except on the plate based on MIP of (+)-norephedrine. Most adrenergic drugs structurally related to print molecules were completely resolved into two spots with the MIP plates. In general, the retention of (+)-isomers (or 1S-isomers) was greater than that of (–)-isomers (or 1R-isomers), indicating the stereoselectivity of the MIPs with the former isomers. Moreover, the role between the chemical structures of the analytes with chiral recognition of the MIPs has been investigated. The proposed method enables rapid determination of enantiomers and screening of large numbers for optical purity of adrenergic drugs.
50 citations
TL;DR: In this article, the causes and factors involved in methyl mercury formation during analysis were investigated using a hyphenate HPLCUV-PCO-CVAFS and a HPLC-ICP-MS technique.
46 citations
TL;DR: In this article, a dichloromethane extract of triterpenoids from seeds of the Neem tree (Azadirachta indica) can be fractionated rapidly and with economic use of solvents using the Biotage™ flash chromatography system.
Abstract: A dichloromethane extract of the triterpenoids from seeds of the Neem tree (Azadirachta indica) can be fractionated rapidly and with economic use of solvents using the Biotage™ flash chromatography system. The fractions can be analysed by thin layer chromatography (TLC), or quantitatively, by supercritical fluid chromatography or high performance liquid chromatography (HPLC), for the determination of 11 tetranortriterpenoids, including the natural insecticide azadirachtin. After a second pass through the Biotage flash column, pure compounds, including azadirachtin and salannin can be obtained directly, although these compounds comprise less than 0.3% of the total mass of the seeds extracted and are present in a complex mixture of similar substances. Copyright © 1999 John Wiley & Sons, Ltd.
44 citations
TL;DR: In this paper, a method for the determination of the percentage of the arabica coffee in mixtures of roasted coffee is proposed, where the sterol content of roasting coffee blends is determined by extracting the coffee oil, saponifying the lipids and the sterols present in the unsaponifiable fraction were separated by thin layer chromatography.
Abstract: A method for the determination of the percentage of the arabica coffee in mixtures of roasted coffee is proposed. The sterol content of roasted coffee blends was determined by extracting the coffee oil, saponifying the lipids and the sterols present in the unsaponifiable fraction were separated by thin layer chromatography. Then, they were converted into trimethyl silyl derivatives and analysed by gas chromatography. Twelve sterols were determined in roasted coffee samples which were mixtures of the arabica and robusta classes. Considering the sterols as chemical descriptors, principal component regression was applied. Δ5avenasterol was found to be a very adequate variable to establish the arabica percentage in roasted coffee blends. The method was applied to the determination of the arabica–robusta composition of commercial roasted coffee samples.
43 citations
TL;DR: In this article, a planar electrochromatographic elution was applied to the separation of pirimicarb and a number of related compounds by planar Electrochromatography.
39 citations
Patent•
23 Mar 1999
TL;DR: An oxirane derivative and process for preparation of the same, having a high purity characterized in terms of gel permeation chromatography and thin layer chromatography, is described in this article.
Abstract: An oxirane derivative and process for preparation of the same, having a high purity characterized in terms of gel permeation chromatography and thin layer chromatography. The oxirane derivative is useful as a starting material for medical purposes, and mainly drug delivery systems.
TL;DR: In this paper, two methods of fractionation of coal tar pitch, one based on solvent solubility separation and the other on preparative thin layer chromatography were compared for effectiveness of the separation.
01 Nov 1999-Comparative Biochemistry and Physiology Part C: Pharmacology, Toxicology and Endocrinology
TL;DR: Six of the component oligosaccharides were separated and purified by gel filtration and preparative thin layer chromatography and all except lacto-N-novopentaose I have been previously found in human milk or colostrum.
TL;DR: In this paper, a coal tar pitch from the high temperature coking of coal has been fractionated by planar chromatography into fractions immobile in pyridine, mobile in pyrolysis-gas chromatography/mass spectrometry at 770 and 1300°C, and by nuclear magnetic resonance (NMR) methods (1H in solution and 13C (CPMAS TOSS) in the solid state).
Abstract: A coal tar pitch from the high temperature coking of coal has been fractionated by planar chromatography into fractions immobile in pyridine, mobile in pyridine but not mobile in acetonitrile, and mobile in both solvents. Fractions have been examined by pyrolysis-gas chromatography/mass spectrometry at 770 and 1300 °C, and by nuclear magnetic resonance (NMR) methods (1H in solution and 13C (CPMAS TOSS) in the solid state). The fraction mobile in both solvents resembled the whole pitch in that the pyrolysis products were all polycyclic aromatics. The fraction mobile only in pyridine and the immobile fraction both gave alkene fragments as the most abundant pyrolysis products with polycyclic aromatics of low intensity only. The pyridine mobile and immobile fractions were shown by size exclusion chromatography with ultraviolet (UV) absorbance detection and by UV fluorescence spectroscopy to consist of large aromatic clusters and of large molecules. It is likely that the large aromatic clusters did not pyrolyse into fragments able to pass through the GC column. NMR methods confirmed the apparent trend of increasing aliphatic content with increasing immobility in thin layer chromatography. Copyright © 1999 John Wiley & Sons, Ltd.
TL;DR: A semi-micro method has been developed using preparative thin-layer chromatography (TLC) to separate acylglycerols for the subsequent analysis by gas chromatography-mass spectrometry (GC-MS) to identify sn-1(3)- and sn-2-MAG isomers.
TL;DR: Direct enantioseparation of (+/-)-ibuprofen and (+/--flurbiprofen was achieved by two-dimensional thin-layer chromatography on silica gel plates impregnated with optically pure (-)-brucine as chiral selector.
Abstract: Direct enantioseparation of (+/-)-ibuprofen and (+/-)-flurbiprofen was achieved by two-dimensional thin-layer chromatography on silica gel plates impregnated with optically pure (-)-brucine as chiral selector. The solvent systems that were successful in resolving both the compounds were acetonitrile-methanol (16:3 v/v) for the first dimension and acetonitrile-methanol-water (16:3:0.4, v/v) for the second dimension. Iodine vapour was used for detection; the detection limit for both (+/-)-ibuprofen and (+/-)-flurbiprofen was 0.1 microgram.
TL;DR: The structural composition of sardine oil triacylglycerols (TAGs) has been studied in this paper, with the result of 65 chromatographic peaks resolved.
Abstract: The nutritional benefits attributed to fish oils have been the basis for the study of the structural composition of Sardine oil triacylglycerols (TAGs). TAGs were separated reversed-phase high performance liquid chromatography (RP-HPLC) with the result of 65 chromatographic peaks resolved. The problem of identification was avoided by the use of two more chromatographic techniques. Separation of the sardine oil TAGs into fractions by silver-ion thin layer chromatography (TLC) and its subsequent fatty acid analysis by gas chromatography allowed identification of 59 of the 65 chromatographic peaks. From those peaks, the major was trimyristin (MMM), with 8.22 % of the total. Dioleoyl-acyl-glycerol (OPO, OOE), dipalmitoyl-acyl-glycerol (PPO, PPPo), dipalmitoleoyl-acyl.glycerol (PoPoO) and dieicosapentaenoyl-acyl-glycerol (EEP) species were found in important amounts.
TL;DR: It is demonstrated for the first time unambiguously that NeuAc-Gal-Cer is the main ganglioside fraction in fish liver and that electrospray ionization-mass spectrometry (ESI-MS) can be used to elucidate the chemical composition of a gangliosiside fraction obtained by convenient extraction of a HPTLC band.
Abstract: Ganglioside patterns from crucian carp brain, muscle, and liver as well as liver gangliosides of roach, carp, the cichlid Oreochromis mossambicus , pigeon, dwarf hamster, and calf were comparatively analyzed by high performance thin layer chromatography (HPTLC). To achieve a rapid estimation on potentially interesting ganglioside compounds, electrospray-ionization mass spectrometry (MS) was directly applied to a chloroform/methanol extract of the major TLC band of crucian carp liver. The spectrum, obtained from a few micrograms of this crude biological sample, revealed a series of peaks corresponding to GM4-like monosialoganglioside species. GC-MS analysis revealed hydroxylated fatty acids ranging from 2 h 20 min:0 to 2 h 26 min:0 for the [M'H] − ions of m / z 1061–1145. Collision induced dissociation tandem MS/MS of the major peak with a [M'H] − ion of m / z 1117 demonstrated the presence of N -acetylneuraminic acid as sialic acid compound. The sugar composition was confirmed by GLC as galactose and sialic acid in a 1:1 molar ratio. Thus, the structure of the ion at m / z 1117 is N -acetylneuraminylgalactosylceramide (NeuAc-Gal-Cer) with the long chain base d18:1 and the hydroxylated fatty acid 2 h 24 min:0. The results demonstrate for the first time unambiguously that NeuAc-Gal-Cer is the main ganglioside fraction in fish liver and that electrospray ionization-mass spectrometry (ESI-MS) can be used to elucidate the chemical composition of a ganglioside fraction obtained by convenient extraction of a HPTLC band.
Journal Article•
TL;DR: Saponification has been employed in order to hydrolyze the carotenoid esters, remove fatty material and destroy chlorophyll, and this optional step facilitates subsequent carOTenoid separation, identification and quantification.
Abstract: The carotenoids are extremely reactive and consequently unstable due to their long system of conjugated double bonds. Several precautions, such as protection against light and oxygen, use of low temperature and antioxidants, analysis in the shortest possible time, should be taken during isolation and chromatography. The food samples, preferably fresh, are homogenized and immediately extracted with a suitable organic solvent. Saponification has been employed in order to hydrolyze the carotenoid esters, remove fatty material and destroy chlorophyll. This optional step facilitates subsequent carotenoid separation, identification and quantification. The separation of carotenoids is usually carried out by column chromatography, thin layer chromatography and high performance liquid chromatography, in analytical or preparative scale, on many stationary phases such as silica-gel, alumina, MgO, Ca(OH)2 and reversed-phase material (C18 and C30). The choice of the most suitable chromatographic method depends on the amount of sample, carotenoid composition, resolution, speed and purity required. Examples of carotenoid separation in different stationary phases will be shown and discussed.
TL;DR: The efficiency of silver ion and reversed-phase thin layer chromatography in the analysis of triacylglycerols is discussed in this paper and examples are presented that demonstrate the achievements of thin-layer Chromatography in elucidating the triplets structure of natural and modified lipid samples.
Abstract: The efficiency of silver ion and reversed-phase thin layer chromatography in the analysis of triacylglycerols is discussed in this paper. The experimental conditions that allowed for the conversion of these techniques into full-scale quantitative analytical methods are presented and details of the respective protocols are given. Examples are presented that demonstrate the achievements of thin-layer chromatography in elucidating the triacylglycerol structure of natural and modified lipid samples.
Journal Article•
TL;DR: Inhibitory compounds of angiotensin converting enzyme (ACE) were separated from Doenjang (traditional Korean fermented soybean paste) using gel permeation chromatography (GPC), in which two fractions with high ACE inhibitory activities were obtained.
Abstract: Inhibitory compounds of angiotensin converting enzyme (ACE) were separated from Doenjang (traditional Korean fermented soybean paste). Water extracts from Doenjang which showed ACE inhibitory activity were separated with gel permeation chromatography (GPC), in which two fractions with high ACE inhibitory activities were obtained. The first fraction from GPC was further isolated by semi-preparative reverse phase preparative-HPLC (high performance liquid chromatography) and 2-dimensional electrophoresis/thin layer chromatography (TLC). The purified spot had molecular weight of 759 daltons and ninhydrin-positive non-peptide. The second fraction from GPC was also further isolated by semi-preparative reverse phase HPLC and HPLC. One fraction with high ACE inhibitory activity was purified and characterized. Molecular weight of this fraction by LC-MS was 272.34 daltons. The active fraction was identified as Arg-Pro with ACE of .
TL;DR: Inhibition of conversion of l- arginine to l-citrulline by NG-monomethyl-l-arginine acetate, a specific inhibitor of NOS, confirmed the NOS assay described in this investigation.
TL;DR: Practical application of the HPTLC system is demonstrated by analysis of grain extracts from wild type and low-phytate mutant barley as well as phytate degradation products resulting from barley phytase activity.
TL;DR: The influence of temperature on retention and separation of cholesterol and bile acids, using reversed-phase thin-layer chromatography, was studied and the elution order of steroids under the conditions investigated was discussed.
TL;DR: The modification of silica gel with aluminium by a coating method was effective for the preparation of a silica-based stationary phase, which acted as a cation exchanger under strongly acidic conditions.
TL;DR: Advances in the applications of thin-layer chromatography and high-performance thin- layer chromatography for the separation, detection, and qualitative and quantitative determination of pesticides, other agrochemicals, and related compounds are reviewed for the period 1998-2000.
Abstract: Advances in the applications of thin-layer chromatography (TLC) and high-performance thin-layer chromatography (HPTLC) for the separation, detection, and qualitative and quantitative determination of pesticides, other agrochemicals, and related compounds are reviewed for the period 1998-2000. Analyses are covered for a variety of samples, such as food, biological, and environmental, and for residues of pesticides of various types, including insecticides, herbicides, and fungicides, belonging to different chemical classes. References on formulation analysis, hydrophobicity studies, and the use of TLC and thin-layer radiochromatography (TLRC) for studies of pesticide metabolism, degradation, uptake, and related studies are also included.
TL;DR: The successful application of tandem mass spectrometry to the analysis and identification of morphine following thin-layer chromatography suggests that this approach has practical utility for confirming the identity of abused drugs detected by thin- layer chromatography.
TL;DR: In this article, two overpressured layer chromatography (OPLC) systems were developed for the screening of toxicologically relevant basic drugs in forensic and clinical contexts, which were tested on high performance silica gel plates.
Abstract: Two overpressured layer chromatography (OPLC) systems were developed for the screening of toxicologically relevant basic drugs in forensic and clinical contexts. The OPLC1 system was trichloroethylene - methylethylketone - n-butanol - acetic acid - water 17+8+25+6+4 and the OPLC2 system was butyl acetate - ethanol - tripropylamine - water 85+9.25+5+0.75 with presaturation. Both systems were tested on high performance silica gel plates. The Rf values of the drugs were reproducible, the peak shapes were symmetrical, and the chromatographic systems showed low mutual correlation (r = 0.103). The separation numbers (SN) were 27.5 and 29.2 for OPLC1 and OPLC2, respectively, which are more than two times higher than those obtained with TLC systems in general. The combination of the systems was demonstrated to be feasible in the screening for drugs in autopsy urine samples, utilizing automated identification by hRf c/UV library search with combined dual-system reporting.