Showing papers on "Silica gel published in 1976"
TL;DR: In this article, a detergent (cetyltrimethylammonium bromide) is added at around the 1% level to a propanol-water eluent.
279 citations
TL;DR: The phospholipid class composition of various rat tissues and a Morris 7777 hepatoma has been determined and compared with values from the literature.
213 citations
TL;DR: In this paper, a summary of spherulitic crystallization mechanisms is presented, and emphasis is placed on impurity and viscosity requirements, and a viscous colloidal origin is postulated for cherts and other siliceous sedimentary rocks that contain abundant silica microspheres.
Abstract: Under hydrothermal conditions (3 kb, 100/sup 0/ to 300/sup 0/C, 25 to 5,200 hr), freshly solidified silica gel crystallized to quartz, predominantly in the form of chalcedonic spherulites. No intermediate crystalline phases in the transition from amorphous silica to quartz were detected. Chalcedony that made up the synthetic spherulites was either length-slow, length-fast, or both, depending on the experimental conditions. These findings contrast with the hypothesis that chalcedony derived from silica gel should be length-fast. In experiments in which blue-green algae had been embedded in the silica gel, spherulite nucleation occurred preferentially on surfaces of particulate organic matter, and the chalcedony generally was length-slow. A summary of spherulitic crystallization mechanisms is presented, and emphasis is placed on impurity and viscosity requirements. Considering these requirements and the experimental results, a viscous colloidal origin is postulated for cherts and other siliceous sedimentary rocks that contain abundant silica microspheres. The seemingly biological attributes of quartz microspheres in Precambrian iron formation cherts can be explained by strictly inorganic processes related to spherulitic crystallization of colloidal precursors.
133 citations
TL;DR: In this article, the effect of the exclusion properties of silica gel on retention data is considered and a modified retention volume equation that takes into account these exclusion properties is given, tested against retention data determined for three different solutes chromatographed on three silica gels of widely different porosities.
125 citations
TL;DR: In this paper, the separation of a number of carbohydrates on Partisil-10 PAC, a 10-μm silica gel with a permanently bonded polar phase, is described.
99 citations
LGC1
TL;DR: In this article, the preparation of high-efficiency ion exchange column packings based on silica gel of 5-μm particle size was investigated, and the effects of the variation of operating parameters on the separation of nucleosides using the strong cation exchanger and the use of the ion exchange materials in a number of chromatographic applications was described.
60 citations
TL;DR: In this paper, a semiquantitative model for the surface of a silica-alumina catalyst is proposed, based on a previous model for surface of silica gel.
56 citations
TL;DR: One combination, viz., watersaturated ethylacetate: n -propanol on silica gel thin layers was found to be particularly useful in separating thymine dimers from thymine by one-dimensional chromatography.
54 citations
TL;DR: In this paper, the authors used 3-aminopropyltriethriethoxysilane or N-methyl derivative of the same reagent to produce a material with an amino silyl functional group.
Abstract: Silica gel was reacted with 3-aminopropyltriethoxysilane or with the N-methyl derivative of the same reagent to produce a material with an amino silyl functional group. If a water sample in the pH range of 5.0 to 7.5 is passed through a short column of this material, iron(II) and copper(II) are completely retained, while calcium(II) and magnesium(II) pass through. This permits an accurate water hardness titration withoug adding any cyanide. (auth)
43 citations
TL;DR: A rapid, sensitive and selective method for the determination of carbamazepine and its major metabolite in plasma has been developed and other commonly used anticonvulsants can be determined in the same procedure without interference.
43 citations
TL;DR: The effect of heat treatment on the properties of silica gel has been studied by means of dilatometry, thermogravimetry, surface area by BET method, optical and electron-scanning microscopy, and infrared spectroscopy as discussed by the authors.
TL;DR: In this paper, it was shown that gypsum grown in silica gel in the presence of inorganic compounds were needle-shaped, while the addition of organic compounds may alter the habit into a more stubby modification.
TL;DR: The methyl phosphotriester of thymidylyl(3'-5')thymidine, Tp(Me)T, was obtained as a product of enzymic digestion of N-[14C]methyl-N-nitrosourea-methylated DNA or of N-methyl- N-nitrogen- methylated [ 14C]thymine-labelled DNA.
TL;DR: Reasonable cost, simplicity of preparation and usage, and good chemical and physical stability render the silver halide phases applicable in routine analysis and quite competitive with many commercially available chemically bonded stationary phases.
Abstract: The use of silver halide impregnated supports for high-pressure liquid chromatographic (HPLC) and thin-layer chromatographic (TLC) analysis of drug substances has been studied. Successful separations of xanthines and mixtures containing barbiturates, xanthines, ergot alkaloids, and tropane alkaloids have been achieved with isocratic conditions or by using simple gradients. The Ag-supports show a similar behavior as many chemically bonded stationary phases, such as modification fo adsorption sites on silica gel to give lower retention but better specificity; rapid reconditioning in connection with gradient elution (3-5 minutes). Reasonable cost, simplicity of preparation and usage, and good chemical and physical stability render the silver halide phases applicable in routine analysis and quite competitive with many commercially available chemically bonded stationary phases.
TL;DR: Active supported nickel clusters were prepared by pyrolysis of di-and tri-nickel cyclopentadienyl carbonyl cluster compounds dispersed on silica gel and Vycor glass; they exhibited specific H2 and CO adsorption and catalytic activity for olefin hydrogenation and the "oxo" reaction as discussed by the authors.
Abstract: Active supported nickel clusters were prepared by pyrolysis of di- and tri-nickel cyclopentadienyl carbonyl cluster compounds dispersed on silica gel and Vycor glass; they exhibited specific H2 and CO adsorption and catalytic activity for olefin hydrogenation and the ‘oxo’ reaction.
TL;DR: High-speed liquid chromatography in the system silica gel/dry n-hexane and ultraviolet spectrometry have been used to study the composition of various types of commercially available mixtures of chlorinated biphenyls, with special attention to highly chlorinated products.
TL;DR: In this article, selective adsorption of trace arsenite and arsenate anions in an aqueous solution by ferric hydroxyde supported on silica gel particles was investigated.
Abstract: Selective adsorption of trace arsenite- and arsenate anions in an aqueous solution by ferric hydroxyde supported on silica gel particles was investigated. Silica gel particles were loaded with ferric hydroxide of the range of 1 – 3 wt. % in terms of Fe based on the dry gel, and the extent of adsorption of arsenite or arsenate ion measured by batch- and column processes, being the highest at pH 6 in the presence of diverse foreign ions. With the use of silica gel containing 3.3 wt. % Fe, as much as 0.07 m mol of arsenic per gram of dry gel was adsorbed.
TL;DR: In this paper, the reaction rate was zero order in the partial pressure of CO and CO2; whereas, the rate was first order with respect to the N2O partial pressure, depending upon the pressure and temperature.
TL;DR: In this paper, gas chromatography of monoterpene hydrocarbon mixtures from essential oils using silica gel as adsorbent alterations in the composition of the mixtures were observed by means of gas chromography.
Abstract: During LSC of naturally occurring monoterpene hydrocarbon mixtures from essential oils using silica gel as adsorbent alterations in the composition of the mixtures were observed by means of gas chromatography. Impurities (metals) and active sites on dried silica gels were found to be responsible for a series of isomerizations of a number of the constituents. After purification by washing the silica gel with acid and base and after deactivation of the dried silica gel by adding water (5%) the isomerization processes could be avoided. This was tested by means of the monoterpene hydrocarbon mixtures of three essential oils and a number of pure monoterpene hydrocarbons.
TL;DR: Phosphatidylserines have been prepared from bovine brain using DEAE column chromatography using a method involving AgNO 3 -impragnated silica gel H thin-layer chromatography and a detailed analysis was made of the fatty acid composition of the various fractions using gas chromatography.
TL;DR: A variety of protected synthetic peptides were purified by high-performance liquid chromatography on pre-packed silica gel columns, varied in protecting groups, amino acid composition and molecular weight.
TL;DR: Two deactivation modes for silica gels commonly used in high-performance liquid chromatography are compared as discussed by the authors : deactivation of silica by introducing a known amount of water and deactivation by thermal treatment.
Patent•
20 Jul 1976
TL;DR: Gels are formed from silica powders and hydrochloric acid and then impregnated into a polymeric foam and the resultant sheet material can then be used in applications where the transport of chloride ions is desired as mentioned in this paper.
Abstract: Gels are formed from silica powders and hydrochloric acid. The gels can then be impregnated into a polymeric foam and the resultant sheet material can then be used in applications where the transport of chloride ions is desired. Specifically disclosed is the utilization of the sheet in electrically rechargable redox flow cells which find application in bulk power storage systems.
TL;DR: In this paper, the authors proposed a method to measure the effect of a single person's actions on the overall performance of the entire team. But, the results showed that 50% of the players were negatively affected.
Abstract: アミノ酸およびアマイドをシリカゲル薄層クロマトグラフィにより分離し, その重窒素濃度を発光分光分析法により測定する方法についていくつかの検討を行った。その結果シリカゲルからの窒素の汚染が大きいために, シリカゲルをそのまま封電管内に封入する従来法による測定では, かなりの誤差を生じることが明らかになった。この汚染を回避するために, シリカゲルを560℃で30分焼き, さらに分離, 採取されたシリカゲル中のアミノ酸およびアマイドを50%エタノールで溶出し, 封電管中にはシリカゲルを含まない方法を考案した。これにより窒素の汚染量は従来法の1/5程度まで減少した。この方法を植物より分離されたアミノ酸およびアマイドの重窒素濃度の測定に適用した結果, 従来法よりもすぐれていることが明らかにされた。
TL;DR: In this article, the vibrational spectra of species adsorbed on thin layer chromatography (TLC) plates have been studied by Fourier transform infrared (FT-ir) and Raman spectrometry.
Abstract: Methods of measuring the vibrational spectra of species adsorbed on thin layer chromatography (TLC) plates have been studied by Fourier transform infrared (FT-ir) and Raman spectrometry. Previous measurements of the transmittance spectra of species separated by TLC (with the adsorbent deposited on AgCl plates) showed poor signal/noise ratio at high frequency due to scattering by the adsorbent. Scattering has been minimized in these experiments by treating the TLC plate with Fluorolube, an infrared mulling oil whose refractive index closely matches that of the adsorbent. Spectra of chlorinated hydrocarbon pesticides on silica gel and alumina adsorbents measured in this way show differences which can be correlated with the mechanism of adsorption. FT-ir spectra of compounds on TLC plates can be obtained from microgram quantities of sample but Raman spectrometry is not as sensitive, requiring at least 200 μg of sample. The Raman bands of adsorbed pesticides are weak and considerably broadened with respect to the corresponding bands in the spectra of the pure samples.
TL;DR: The technique described, is rapid, less costly than conventional methods and provides an accurate assessment of sphingolipid hydrolase activity and should be of considerable value in those areas which require the rapid analysis of large numbers of samples, such as in screening for the sphingo-lipidoses or for enzyme purification studies.
TL;DR: In this article, a series of alkyl and (mono-, di- and poly-) oxaalkyl-dimethylsilanols are described and the stability of these compounds on storage is considerably increased by previous filtration through a silica gel column.
Abstract: The preparation of a series of alkyl- and (mono-, di- and poly-) oxaalkyl-dimethylsilanols is described. The stability of these compounds on storage is considerably increased by previous filtration through a silica gel column.
TL;DR: Several pesticides have been investigated for their fluorigenic properties on acidic and basic aluminium oxide layers and the results are compared with those already reported for silica gel layers.