Showing papers in "Journal of Chromatography A in 1977"

TL;DR: Although many of the C-3 substituted indoles such as indole-3-acetic acid and tryptamine had colors in the reddish-violet-blue color region, most exhibited sufficient color differentiation to allow their identification by thin-layer chromatography.

TL;DR: Several technical problems such as the following have been solved in order to perform micro-high-performance liquid chromatography (MHPLC): (1) a method for packing a narrow column with stationary phase and selection of suitable column material; (2) preparation of micro-flow cells suitable for a micro-column; (3) improvement of the detector system; (4) methods for the pressurized passage of mobile phase at low flow-rates and for injection of a micro amount of sample solution; and (5) gradient elution methods suitable for microcolumns as mentioned in this paper.

TL;DR: The efficiency of the method is superior to that obtained on the conventionally used ion-exchanger columns, except for hydrophilic amino acids and peptides that are poorly retarded, Nevertheless, with a suitable ionic surfactant in the mobile phase, non-polar stationary phases can be used for the separation of these species.

TL;DR: In this paper, five commercially available reversed phases are examined, and the effects of chain length, carbon content and extent of derivatization on wettability, retention and selectivity are investigated.

TL;DR: The retention behaviour of amino acids in phase systems consisting of a hydrophobic solid support as the stationary phase and water-organic solvent mixtures containing a small amount of an anionic detergent as the mobile phase was investigated and shows a greater selectivity than conventional ion-exchange systems towards amino acids.

TL;DR: Specific methods have been devised for the simultaneous determination of the guanidino-type antihypertensive agent debrisoquine and its 4-hydroxy metabolite in human urine, involving in situ derivatisation with acetylacetone, extraction of the resulting pyrimidines, and gas chromatography using a flame-ionisation detector or a nitrogen-specific detector.

TL;DR: In this article, some factors affecting the efficiency of packing microparticulate liquid chromatography columns are discussed with some experimental evidence on the most critical factors and upward packing of a dilute slurry is considered to have some advantages.

TL;DR: In this paper, the main characteristics of the bonded reversed-phase chromatography (BRPC) are described and some of the advantages of this technique and a few typical applications are reported.

TL;DR: In this paper, the polarity and selectivity of several mobile phases used with reversed-phase high-pressure liquid chromatography columns were studied, including water, methanol, acetonitrile and tetrahydrofuran.

TL;DR: In this paper, a new method of direct sampling for capillary columns is presented and compared with the known techniques with respect to resolution, reproducibility of retention, decomposition of sensitive sample components and discrimination of high-boiling components in quantitative analysis.

TL;DR: In this paper, a method for the quantitative conversion of traces of aldehydes and ketones to their 2,4-dinitrophenylhydrazones at room temperature is presented.

TL;DR: In this paper, the preparation of chemically bonded stationary phases based on a silica support for aqueous exclusion chromatography is discussed, where a defined amount of functional groups can be bonded on the silica surface only if the appropriate silane is prepared prior to binding it to the surface.

TL;DR: A rapid and efficient method for the separation of (phospho)lipids by high-performance liquid chromatography using n-hexane-2-propanol-water mixtures as the solvent system is described and separation of molecular species can also be achieved, as is shown for phosphatidylcholines and sphingomyelins.

TL;DR: The conformational changes observed with sodium bromide and thiocyanate were accompanied by decreasing protein-adsorbent interaction, except for ovalbumin in 3 M sodium thiOCyanate.

TL;DR: The separation properties of five nonapeptides on commercial reversed-phase materials have been investigated and the effects of pH, salt concentration and solvent composition have been studied.

TL;DR: In this paper, column chromatographic data reported by Scott and Kucera for systems of the type pentane + polar solvent (S)-silica result in linear plots of log V′ versus log Cs and are thus in agreement with adsorption models based on the law of mass action.

TL;DR: The method is rapid and easy to use and is therefore suitable for checking the purity of derivatives during the preparation of chlorophylls and their derivatives.

TL;DR: A micro-method for the identification of most acidic mucopolysaccharides by agarose gel electrophoresis with three different buffer systems with mixed results for barbital, diamine and diaminopropane buffers is described.

TL;DR: Selenium can be determined quantitatively in biological samples after nitric acid-magnesium nitrate digestion and formation of 5-nitropiazselenole, by extraction into toluene for gas-liquid chromatography with electron-capture detection.

TL;DR: Mass spectrometric analysis (high and low resolution) has confirmed the identity of M and identified one of the additional metabolites as methoxyparacetamol and one of these metabolites may be associated with liver damage.

TL;DR: In this article, a method for the analysis of phenolic compounds in plant tissue is described for extraction of the phenols with aqueous alcohol is followed by analysis by high-performance liquid chromatography.

TL;DR: A quantitative high-pressure liquid chromatographic assay of warfarin and its diastereoisomeric alcohols and 4'-, 6, 7, 8- and benzylic hydroxylated metabolites was accomplished using a reversed-phase, microparticle column (muBondapak/C18) employing 1.5% acetic acid (pH 4.7)-acetonitrile (69:31) as solvent.

TL;DR: In this article, high performance liquid chromatographic separations of chelates at nanogram levels by adsorption chromatography on silica gel are reported. 1,2-Diketobisthiobenzhydrazones, dialkyldithiocarbamates and 1, 2-diketabisthiosemicarbazones were used as chelate-forming ligands.

TL;DR: The complete mass spectra of the trimethylsilyl derivatives of 46 amino acids are presented in this paper in terms of the common fragmentation pathways and factors controlling the fragment formation.

TL;DR: The correlation between results obtained by bioassay and by the proposed HPLC method is highly significant and suggests the use of HPLC as an alternative technique for stability and content-uniformity tests on dosage forms and concentrates.

TL;DR: In this article, the use of a new carbonaceous adsorbent, Ambersorb XE-340 (Rohm and Haas, Philadelphia, Pa., U.S.A.), was investigated.

TL;DR: The analytical system described in this paper consists of a gas chromatograph, an atmospheric pressure ionization mass spectrometer designed for operation in the negative ion mode, and a computer.