β-Cyclodextrin-Bonded Chiral Stationary Phase for Thin-Layer Chromatographic Separation of Enantiomers

JPC – Journal of Planar Chromatography – Modern TLC -     

TLC Separation of Amino Acids with a Green Mobile Phase

JPC – Journal of Planar Chromatography – Modern TLC - Thin-layer chromatography (TLC) of fifteen amino acids was performed using silica gel and alumina impregnated with micellar...     

Thin-Layer Chromatography with an Isolated Support and Forced Flow of the Mobile Phase

JPC – Journal of Planar Chromatography – Modern TLC -     

Direct Resolution of Aromatic Alcohols by Planar Chromatography on Tribenzoylcellulose as Chiral Stationary Phase

JPC – Journal of Planar Chromatography – Modern TLC -     

Bioanalysis of Naproxen by High Performance Reversed Phase Liquid Chromatography with Photometric and Fluorimetric Detection

Abstract

Methods for the quantitative determination of NAPROXEN and its main metabolite in plasma and urine are described. The separation is based on reversed phase liquid chromatography with LiChrosorb RP 8 (5 μm) as the support and methanol/phosphate buffer pH 7 as mobile phase, in some cases with addition of tetrabutyl ammonium ion as ion-pairing agent to improve the chromatographic selectivity. With UV-detector and a simple filter fluorometer an extraction-evaporation procedure is used for both plasma and urine determinations, while the high selectivity and sensitivity of a sophisticated fluorescence detector permits the direct injection of diluted samples on to the column. Use of an internal standard improves the within-run precision (s_rel%), which for plasma determinations of NAPROXEN are - with UV-detection, 0.2 – 1.7% (range 10 – 40 μg/ml), with filter fluorometer, 2.4 – 5.9% (range 12 – 58 μg/ml), and with fluorescence detector, 0.8 – 4.1% (range 5 – 20 μg/ml).     

Effect of Non-Aqueous Mobile Phase Composition on the Retention of Macrocyclic Antibiotics in RP-TLC

JPC – Journal of Planar Chromatography – Modern TLC - The retention behavior of five macrocyclic antibiotics (erythro-mycin, troleandomycin, tylosin, rifamycin B, and rifampicin) has...     

Gas Phase Formation of the Interstellar Molecule Methyltriacetylene

Methyltriacetylene – the largest methylated polyacetylene detected in deep space – has been synthesized in the gas phase via the bimolecular reaction of the 1-propynyl radical with diacetylene under single-collision conditions. The barrier-less route to methyltriacetylene represents a prototype of a polyyne chain extension through a radical substitution mechanism and provides a novel low temperature route, in which the propynyl radical piggybacks a methyl group to be incorporated into methylated polyynes. This mechanism overcomes a key obstacle in previously postulated reactions of methyl radicals with unsaturated hydrocarbon, which fail the inclusion of methyl groups into hydrocarbons due to insurmountable entrance barriers thus providing a fundamental understanding on the electronic structure, chemical bonding, and formation of methyl-capped polyacetylenes. These species are key reactive intermediates leading to carbonaceous nanostructures in molecular clouds like TMC-1.     

The Mobile Phase Motion in Ascending Micellar Thin-Layer Chromatography with Normal-Phase Plates

JPC – Journal of Planar Chromatography – Modern TLC - The physical-chemical characteristics (surface tension and viscosity) of micellar mobile phases based on the cationic surfactant...     

Enhancement of Mobile Phase Velocity in TLC by Means of an External Alternating Electric Field

JPC – Journal of Planar Chromatography – Modern TLC - In normal TLC practice, migration of the mobile phase through the layer is controlled by capillary forces. Under these conditions...     

Retention-Mobile Phase Relationships for Methylxanthines and Biogenic Amine Metabolites in Adsorption Thin-Layer Chromatographic Systems

JPC – Journal of Planar Chromatography – Modern TLC - Relationships between RF values and mobile-phase composition have been determined for six methylxanthines and acidic and neutral...     

Thin-Layer Chromatographic Enantioresolution of (RS)-Ketorolac Using L-Amino Acids as Chiral Additive in Stationary Phase

JPC – Journal of Planar Chromatography – Modern TLC - Direct resolution of enantiomers of (RS)-ketorolac was achieved by thin-layer chromatography on silica gel plates using...     

Effects of Addition of Ion-Pair Reagent to the Mobile Phase on Electroosmotic Flow Velocity in Pressurized Planar Electrochromatography

JPC – Journal of Planar Chromatography – Modern TLC - In the paper, the influence of the addition of different ion-pair reagents — sodium-1-heptane sulfonate (HS),...     

Phase Relationships in the U – Np – O System

U – Np – O phase equilibria was experimentally studied by X-ray diffraction in reducing and oxidizing conditions. Both (U1yNpy)O2 stoichiometric and hyper-stoichiometric compounds were characterized after a heating treatment and resulting lattice parameters were compared to that of previous studies. Synthesized stoichiometric compounds are monophasic and their lattice parameters as a function of Np content are in nice agreement with the Vegard's law between UO2 and NpO2 end-member. Resulting compounds after an oxidizing heat treatment of the stoichiometric samples confirm previous reported U – Np – O relationship. For low Np content, a biphasic hyper-stoichiometric compound is observed: a (U1-y’Npy’)O2+x phase (space group fm-3m) and a (U1-y”,Npy”)3O8 phase (space group C2 mm). For higher Np content (with starting material y = 0.7), only one monophasic hyper-stoichiometric phase (U1-y’Npy’)O2+x appears. Lattice parameters of the (U1-y”,Npy”)3O8 phase differ from the ones of pure U3O8, indicating some Np solubility in this compound. Although Np might remain tetravalent in the (U1y”,Npy”)3O8 phase, this result is in conflict with the assumption of Yamashita et al. (1994).     

Reversed-Phase Stepwise Gradient Thin-Layer Chromatography of 19 Test Dye Mixtures with a Single Void Volume of the Mobile Phase

JPC – Journal of Planar Chromatography – Modern TLC - Satisfactory separation of a test mixture of 19 dyes with a general elution problem was obtained by reversed-phase stepwise...     

Using Lanthanum Fluoride Fine Particles as Stationary Phase for Thin-Layer Chromatography/Fourier Transform Infrared Spectroscopy Analysis

JPC – Journal of Planar Chromatography – Modern TLC - While in situ TLC/FTIR technique has tremendous potential in the analysis of complex mixtures, the conventional stationary phase,...     

Synthesis and Characterization of Alumina R Chemically Modified with n-Octyl for Use as a Stationary Phase in TLC

JPC – Journal of Planar Chromatography – Modern TLC - A stationary phase for thin-layer chromatography has been prepared by attaching 1-octene to alumina R. This stationary phase has...     

Resolution of Beta Blocker Enantiomers by TLC with Vancomycin as Impregnating Agent or as Chiral Mobile Phase Additive

JPC – Journal of Planar Chromatography – Modern TLC - Resolution of the enantiomers of racemic atenolol, metoprolol, propranolol, and labetalol, commonly used β-blockers, has been...     

Use of a Water-in-Oil Microemulsion as Mobile Phase in Complexation TLC of Amino Acids on Silica Layers Impregnated with Metal Cations

JPC – Journal of Planar Chromatography – Modern TLC - A water-in-oil microemulsion has been used for the first time as a mobile phase in thin-layer chromatography of amino acids. A new...     

Thin-Layer Chromatography of Anions — Separation of Coexisting Hexacyanoferrate(II), Hexacyanoferrate(III) and Thiocyanate with a New Mobile Phase

JPC – Journal of Planar Chromatography – Modern TLC - The thin-layer chromatography of eighteen anions has been performed on silica layers with mixed aqueous–organic mobile...     

Study of Viscosity-temperature Properties of Oil and Gas-condensate Mixtures in Critical Temperature Ranges of Phase Transitions

Transport of oil and gas-condensate mixtures of various compositions is found to be accompanied by a slight increase in viscosity in the coldest period when ground temperatures at depth of a condensate pipeline reach 0 – minus 4°С. Fall in temperature of oil fluids under study to minus 10 – minus 30°С is accompanied by a sharp increase in all structural and rheological parameters of the mixture. Even a slight amount of oil added to a gas-condensate mixture causes a significant decrease in viscosity in the negative temperature range. As a result, cloud and pour point of a mixture falls, its amount decreases, the structure of paraffin deposits changes.