Verbesserung und automatische Detektion des Dünnschicht-Chromatogramms

1. Thin-Film Chromatography (TFC). In this new type of solid-liquid chromatography the mobile phase consists of a thin film of liquid moving along the surface of a vacuum-evaporated layer of metal oxides (thickness about 1 μ). The method has been tested by separating eosin from other dyes. Separations were obtained ten times faster than by thin-layer chromatography (TLC). A number of theoretical plates up to 4000/cm was achieved. Nanograms can be detected.
2. Thin-Layer Conductivity Detector (TCD). The chromatogram is recorded during its formation by measuring the electrical conductivity of the moist thin-layer. Chromatograms obtained from indicators and aminoacids are shown. The response is proportional to the amount of sample (measured in the range of 25 to 500 ng). At the present stage of investigations amounts of 10^?8 g (e.g. phenylalanine) are detectable.

     

Chromatographic retention data of N-alkylamides of benzomorpholine-2-carboxylic acid in the study of structure-activity relationships

Summary The adrenolytic activity of N-alkylamides of benzomorpholine-2-carboxylic acid was correlated to their log k and R_M values determined by reversed-phase liquid chromatography and thin-layer chromatography. Mixtures of water with several organic modifiers were used as the mobile phase.     

Influence of gamma-radiation on the behavior of humic acids from peat and tropical soil

HA samples obtained from sedimentary soil and peat in aqueous media were irradiated with -rays, in the dose range from 10 to 100 kGy, with the aim to study the chemical differences in the material before and after irradiation. The materials were analyzed by elemental analysis, UV/Vis spectroscopy (E₄/E₆ ratio), functional groups content, gel permeation chromatography (GPC) and IR spectroscopy. Gas chromatography was utilized to analyze the generated gases. Humic acids from peat and from soil are quite different. After irradiation an increasing in the average molecular weight was observed which depends on the material characteristics. There was observed also a release of CO₂ upon irradiation. By infrared spectroscopy, with the help of computer simulations, the characteristic bands of ester C=O and C–O stretchings reinforces the contribution of carboxylic groups in the condensation process.     

Photolysis of <Emphasis Type="Italic">meta</Emphasis>-azidophenol in solutions

The photolysis of meta-azidophenol in various organic solvents and aqueous solutions is studied by IR spectroscopy, electronic absorption spectroscopy, thin-layer chromatography (TLC), and analytical spot-test reactions. The polymeric derivatives of hydroxylamine are formed in organic solvents (benzene, chloroform, acetonitrile) via the interaction of nitrene with the phenol group of a neighboring m-azidophenol molecule. N-(meta-Hydroxyphenyl)hydroxylamine,—the product of the nitrene reaction with water, is formed in ethanol and aqueous solutions.     

Chromatography with a two-dimensional column

Summary A chromatographic method using a flat, square column developed along one direction and then eluted along the perpendicular direction, using a second retention mechanism widely different from the first one is described. Such a method would offer a potential peak capacity of several thousands, at least ten times more than either conventional column chromatography or two-dimensional thin-layer chromatography. Equipment capable of satisfying the requirements derived from a theoretical study of the operation of a two-dimensional column is also described. Results are satisfactory.Presented at the 14th International Symposium on Chromatography London, September, 1982 as a plenary lecture.     

Moving-window two-dimensional correlation infrared spectroscopy study on structural variations of partially hydrolyzed poly(vinyl alcohol)

In the present study, the molecular chain changes and structural transitions of partially hydrolyzed poly(vinyl alcohol) (PVA) having a 12 mol% acetate unit were analyzed by moving-window two-dimensional (MW2D) correlation infrared spectroscopy combined with differential scanning calorimetry and thermogravimetric analysis. The results show the glass-transition temperature (T _g ) of PVA is clearly distinguished by MW2D correlation infrared spectroscopy, and the acetate groups start to be eliminated around the melting temperature, whereas the free water molecules in PVA are eliminated above T _g. The correlation movements of the O–H stretching modes, including the free hydroxyl groups and the hydrogen bonds, are clearly determined using MW2D correlation infrared spectroscopy. The spectral variations in the C=O stretching region caused by the elimination of the acetate unit from polymer chains are also discussed on the basis of the results of the MW2D correlation analysis. Such results cannot be obtained by traditional infrared spectroscopy owing to the complex overlapping peaks.

A Combined Thin-Layer Chromatography/Micro Infrared Method

Abstract

A method is described for the automatic elution of chromatographed compounds on thin-layer chromatography plates and their subsequent identification by micro infrared spectroscopy.

The method is simple, easy to perform in a few minutes, and requires 5 μg of material, 3 mg of KBr powder, and 150 μl of solvent.     

Nitrosation and bromination of 6-(2'-furyl)imidazo[2,1-b]thiazole and its derivatives

The action of nitrosating agents and bromine on 6-(2-furyl)imidazo[2,1-b]thiazole and its 3-methyl, 5-bromo, and 5-nitro derivatives was studied. The structures of the products were proved by UV, IR, and PMR spectroscopy and thin-layer chromatography.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1353–1358, October, 1972.     

Production and Characterization of Violacein by Locally Isolated Chromobacterium violaceum Grown in Agricultural Wastes

The present work highlighted the production of violacein by the locally isolated Chromobacterium violaceum (GenBank accession no. HM132057) in various agricultural waste materials (sugarcane bagasse, solid pineapple waste, molasses, brown sugar), as an alternative to the conventional rich medium. The highest yield for pigment production (0.82?g?L^?1) was obtained using free cells when grown in 3?g of sugarcane bagasse supplemented with 10% (v/v) of l-tryptophan. A much lower yield (0.15?g?L^?1) was obtained when the cells were grown either in rich medium (nutrient broth) or immobilized onto sugarcane bagasse. Violacein showed similar chemical properties as other natural pigments based on the UV?CVis, Fourier transform infrared spectroscopy, thin-layer chromatography, nuclear magnetic resonance, and mass spectrometry analysis. The pigment is highly soluble in acetone and methanol, insoluble in water or non-polar organic solvents, and showed good stability between pH?5?C9, 25?C100?°C, in the presence of light metal ions and oxidant such as H₂O₂. However, violacein would be slowly degraded upon exposure to light. This is the first report on the use of cheap and easily available agricultural wastes as growth medium for violacein-producing C. violaceum.