Two new compounds from <Emphasis Type="Italic">Phyllanthus niruri</Emphasis>

Three compounds were isolated from Phyllanthus niruri Linn. One effective method, improved dry column liquid chromatography for isolating these compounds, was applied on a silica gel column. It is a combination of conventional dry column chromatographic and flash chromatographic techniques. Structures of those obtained compounds were elucidated by means of spectral techniques including IR, MS, and 1D NMR and 2D NMR. Compound 1 was elucidated as 2,3,5,6-tetrahydroxybenzyl acetate. Compound 2 , 2,4,5-trihydroxy-3-(4,6,7-trihydroxy-3-oxo-1,3-dihydroisobenzofuran-5-yl)-benzoic acid methyl ester, was given the name phyllangin, and compound 3 was named corilagin. Compounds 1 and 2 are new compounds.Published in Khimiya Prirodnykh Soedinenii, No. 5, pp. 380–382, September–October, 2004.     

Demonstration of the Feasibility of Radially Compressed Microbore HPLC Columns

Abstract

This work involved the development of radially compressed, microbore high performance liquid chromatography (HPLC) columns. The design of the overall system and the column are described, and the problems associated with the design features are reported. Variables examined during the course of this work included the column material, column length, packing method, flow rate, radial compression pressure, and internal column pressure. Efficiencies (expressed as plates/meter) are shown for various combinations of those variables and are compared to those obtained using a commercial, steel microbore column.     

A New Spherical Hydroxyapatite for High Performance Liquid Chromatography of Proteins

Abstract

Basic properties of a newly developed hydroxyapatite column and results of its application to the separation of proteins are described. The hydroxyapatite was completely spherical and porous beads in appearance by scanning electron microscopy, and showed superior properties to other types of hydroxyapatite column. The column was mechanically strong enough to show the pressure limit of 140–150 kg/cm². The hydroxyapatite column showed excellent mechanical and chemical stability, and was applicable to high speed and high resolution separation of proteins. Proteins are recovered in high yield after the chromatography.     

Gel Chromatography Column Scanning (GCS) Method of Choice for Quality Control of 99mTc-Plasmin Preparations

Abstract

Gel chromatography column scanning (GCS) is useful for testing compounds labelled with gamma-emitting radionuclides. The elution volume used in this technique is so small that no components of the sample are eluted from the column. In the radioactivity distribution of the sealed column various species are recorded in characteristic zones of the column. Plasmin labelled with ^99mTc is used for scintigraphic detection of deep vein thrombosis. The quality of the ^99mTc-plasmin preparation has been tested by various methods. The GCS method employing small columns offers a very fast testing procedure and adequate resolution for quality control in routine radiopharmaceutical work.     

Evaluation of Column Efficiency by Several Methods

Abstract

Four ways of calculating column efficiency were studied. A moments and a half-height based method appear most sensitive to monitor column ‘lifetime’ and column damage, respectively.     

A benzothiazole-based receptor-immobilised silica nanoparticle as chemosensor for Hg2+

Fluorogenic benzothiazole-based receptor has been easily immobilised onto filter paper and silica nanoparticle by sol-gel reaction. The sensing ability of the benzothiazole-immobilised thin layer filter paper chromatography (TLC-1) was evaluated on the basis of fluorescent changes caused by metal ions that were dropped onto the TLC plate. The TLC-1 exhibited a high affinity and selectivity for Hg²⁺ over other competing metal ions. Therefore, the TLC-1 holds promise as a portable sensor for the detection of Hg²⁺ in aqueous solution. Furthermore, the adsorption capacity of a column packed with SiO₂-1 was evaluated by the application of metal ions under various experimental conditions, such as pH, flow rate and concentration. The SiO2-1 column removed 98% of Hg²⁺ from drinking water containing 10 ppb of Hg²⁺. The adsorption capacity of the SiO₂-1 column was not strongly affected by pH and flow rates.     

Immunochemical Determination of Mouse and Human IgG by Adsorption on C-8 and C-18 Columns

Abstract

Human and mouse IgG are adsorbed directly on a C-8 or C-18 column, followed by reaction on-column with horseradish tagged anti-IgG. Following washing, the enzyme label catalyzes the reaction of hydrogen peroxide with tetramethyl benzidine to produce a dye, which is eluted from the column for measurement.     

High Performance Liquid Chroma Tography of Cytokinins

Abstract

Details are presented of normal- and reversed-phase high performance liquid chromatographic systems suitable for the purification and the separation of a range of cytokinins. In the normal-phase mode an aminopropylsilyl column with volatile organic solvents as mobile phases was used while reversed-phase chromatography was carried out with a base deactivated octadecylsilyl column.     

A Simple Solvent Programmer for Liquid Chromatography. I

Abstract

Equations have been derived from which the dimensions of a solvent gradient generator, coupled to open tubular, micro-packed, semi-micro packed or conventional HPLC columns, may be calculated for a desired gradient volume. Packed and open-tubular generators have been considered. Calculations, using the derived equations, predict that a generator of particular dimensions is needed for each column type. These dimensions are practically feasible for all column types except the conventional column.     

Peak Reversals of Organics on Bentone-34 Modified Gas Chromatographic Columns

Abstract

Enthalpies of solution are reported for 22 different organics chromatographed on a 5% SP 200, 1.75% Bentone 34 gas chromatographic column. Reversal of retention order was observed for butanol and 2,2,5 trimethylhexane as the column temperature was increased. This was probably due to their similar boiling points with different enthalpy of solutions.     

The efficient synthesis of carbon–carbon double bonds via Knoevenagel condensation using red mud packed in a column

Abstract

Red mud (RM) is generated as a by-product during the production of alumina from bauxite ore. In this study, RM packing in a column is used as a catalyst for carbon–carbon double bond formation via Knoevenagel condensation. The reactants are added to the top of the column and then eluted with solvent. The products are collected in high yields and short time. RM packed in a column eliminates a catalyst separation step from the reaction mixture in this work.     

A Chemiluminescence Detector for Transition Metals Separated by Ion Exchange

Abstract

The means by which transition metals, separated as anionic complexes by ion exchange column, can be detected is described. The chemiluminescence of the luminol-H₂O₂ reaction catalyzed by these metals as they emerge from the column and are monitored continuously is used as the detector. Other studies have shown that the emission is proportional to the catalyst concentration; this fact is relied upon in this study.^1–9     

Immobilization of Amylases on Silica Support to Study Breakdown Products of Potato Starch by HPLC

Abstract

Immobilization of α- and β-amylases on epoxypropylsilanized PartiSphere-5 was achieved. Hydrolysis of 2% potato starch solution yielded limit dextrin on α-amylase bound column while a mixture of limit dextrin, maltose and glucose was obtained from β-amylase bound column. The β-amylase bound column converted limit dextrin from α-amylase column into glucose.     

Analysis of Multiring Aromatic Hydrocarbons by HPLC Using a Reverse-Phase Radial Compression Column Systemt

Abstract

The performance of a radially-compressed C₁₈ reverse-phase column system for analysis of multiring aromatics has been assessed in terms of efficiency, resolution and analysis time, and these parameters are compared with those reported for other column systems. The optimum conditions for analysis were established using nine standard aromatic compounds. These conditions are aslo shown to be suitable for analysis of complex mixtures of aromatic compounds obtained from petroleum refinery effluent waters, marine biota and combustion residues (soot).     

Review of Sub-Microliter (Nanoliter) Injection Techniques in Liquid Chromatography

Abstract

In liquid chromatography with “low-dispersion methods”, there is an increasing need to reproducibly inject nanoliter sample volumes. Low-dispersion methods produce very narrow peaks because of short column length, narrow column bore, small particle packing, low particle surface area, open tubular configuration, or combinations of these parameters.

This paper reviews methods used for sub-microliter injections for use with these low-dispersion liquid chromatography methods. Some nanoliter injection methods for open-tubular electrophoresis are also described.     

Determination of Water Soluble Vitamins in Pharmaceutical Preparations Using Liquid Chromatography

Abstract

A liquid chromatography procedure is described for the simultaneous separation of seven water soluble vitamins in pharmaceutical pteparations. The vitamins are separated on a CR bonded-phase column and eluted with a gradient solvent program. A microprocessor controlled variable wavelength ultraviolet detector is used to automatically change detection wavelength to optimize detection of each vitamin. Pharmaceutical preparations are briefly sonicated in a dimethyl sulfoxide-water mixture, centrifuged, and an aliquot injected directly onto the column.     

Determination of impurities in high-purity carbon tetrachloride by gas chromatography-mass spectrometry

The impurities in high-purity carbon tetrachloride (CCl ₄ ) were determined by gas chromatography-mass spectrometry (GC-MS). The use of chromatography of near-saturated vapors allowed the injection of samples up to 1 μL into a capillary column and to achieve specific column efficiency in an isothermal mode of 221,000 t.p./m. The detection limits for impurities were 1 × 10⁻¹ to 1 × 10⁻⁸ wt %.     

A Comparison Between a Micro and an Ultramicro Circle® Cell for on-Line Ft-Ir Detection in a Reverse Phase HPLC System

Abstract

Caffeine and theophylline peaks separated on a 300 × 7.8 mm C₁₈ column could be distinguished qualitatively by FT-IR detection using two types of cylindrical internal reflectance (CIRCLE^®) cells. Detection limits and limits of identification, on the order of 0.2%, are lower for the micro CIRCLE^® cell as compared to the ultramicro CIRCLE^® cell. Maximum sample capacity of the column used was 50uL of a 0.4% solution of caffeine (1.0 micromoles).     

A Multicolumn Ion Chromatographic Determination of Nitrate and Sulfate in Waters Containing Humic Substances

Abstract

A three-column ion chromatographic system for the removal of humic substances from natural waters, and subsequent on-line concentration and determination of nitrate and sulfate using non-suppressed ion chromatography is presented. Humic substances are removed using disposable adsorption columns packed with chemically bonded amine silica material. The sample is directly transfered to an ion exchange column where the anions are concentrated ca 10 times. After reversing the flow, the ions are transferred to a third column where they are separated and quantified. The detection limit is less than 1 mg L^?1 of nitrate or sulfate in water containing 45mgL^?1 of humic acid.     

Column Switching Technique for Group-Type Separation of Different Pah Classes by use of C18-Modified Silica and Polystyrene Packings

Abstract

A column switching technique was developed to realize a group-type separation of PAHs and nitrogen containing PAHs (N-PAHs) applying a C₁₈-immobilized polystyrene packing as well as a C₁₈-modified silica stationary phase. On the first column the group-type separation and also the separation of the N-PAH fraction in single compounds was performed. After backflush and transfer to a second column, the separation of the PAH fraction could be achieved.