Showing papers on "Silica gel published in 1981"
TL;DR: In this paper, a dual retention mechanism that postulates solute retention as a result of both solvophobic (hydrophobic) and silanophilic interactions between the eluite and stationary phase was proposed.
405 citations
302 citations
TL;DR: In this article, the reaction between sodium hydroxide and various forms of silica has been studied and the volume change of solid silica immersed in solution has been measured, showing that if the silica is an absorbant and reactive form such as silica gel, there is an immediate drop in both sodium and hydroxyl concentrations.
278 citations
181 citations
TL;DR: The Salmonella mutation assay has been adapted to a number of experimental procedures used to characterize the chemical components and molecular mechanisms involved in the direct-acting mutagenicity of diesel particle extracts, and the mutagens were found to be unreactive towards purified DNA.
Abstract: The Salmonella mutation assay has been adapted to a number of experimental procedures used to characterize the chemical components and molecular mechanisms involved in the direct-acting mutagenicity of diesel particle extracts. The mutagens were found to be unreactive towards purified DNA. Mutagenic activity was decreased in nitroreductase-deficient bacteria and increased in the absence of oxygen, suggesting that bacterial enzymes active the mutagens. The extract was fractionated by thin layer chromatography using both normal and reverse phase silica gel plates. On normal silica plates, a separation was made between unsubstituted PAH, nitro-PAH and the more polar aromatic compounds. About a third of the mutagenic activity in the particle extract was recovered in fractions containing monosubstituted nitro-PAH compounds. The absorption spectra and reverse phase chromatographic properties indicate 1-nitropyrene is a predominant component but not the only mutagen in these fractions. The remaining activity was in the more polar fractions, and mutagenicity assays using anaerobic conditions and nitro-reductase-deficient bacteria suggest they contain other nitro-substituted compounds.
169 citations
TL;DR: The method was applied for preparative separation of highly complex glycolipids with blood group activity and the separation pattern was highly reproducible.
142 citations
TL;DR: The new metabolite showed less than 1% of the myotropic activity of leukotriene B4 on the guinea pig lung parenchymal strip.
139 citations
TL;DR: In this paper, reversed phase adsorption with octadecyl-modified silica gel was found to give quantitative recoveries of di-, tri-, tetra-and pentachlorophenol, tri- and tetrachloroguaiacol and tri-and tetrachelorocatechol from water.
123 citations
TL;DR: In this article, a reversed-phase high-performance liquid chromatography with octadecyl- or octylsilylated silica gel as the stationary phase provides a powerful tool in the analysis of chloroplast pigments from higher plants and green algae.
116 citations
TL;DR: A rapid solid phase method of oligonucleotide synthesis based on monomeric protected nucleosides has been developed and it is shown that this method can be applied to high-performance liquid chromatography of Na6(CO3)+.
Abstract: A rapid solid phase method of oligonucleotide synthesis based on monomeric protected nucleosides has been developed.
113 citations
TL;DR: In this article, the effect of different variables in triglyceride separation has been studied and it was found that a longer hydrocarbon chain bonded to silica gel as well as the percent coverage improved the separation.
Abstract: High performance reversed-phase chromatography (HPRC) is an efficient and powerful tool gaining momentum in the separation of triglycerides and other lipid components. In the present study the effect of different variables in triglyceride separation has been studied. It was found that a longer hydrocarbon chain bonded to silica gel as well as the percent coverage improved the separation. Smaller particle size packing increased triglyceride resolution. A decrease in mobile phase polarity by increasing the acetone content resulted in a decrease in the retention time and resolution of triglyceride.
TL;DR: Animated microparticulate silica gel was derivatized with the fluorescent tag, dansyl chloride, to produce a chemically modified silica surface that could be examined by fluorescence spectroscopy.
TL;DR: In this article, perchlorate crystals were grown in silica gel by reaction between perchloric acid in the gel and potassium chloride diffusing into the gel from a layer of solution on the gel surface.
TL;DR: In this paper, a number of synthetic aspects of silica-bound complexing agents are considered, and modifications of the procedure for amidization of bound amines and of the diazotizationcoupling sequence are discussed.
TL;DR: In this article, a chiral stationary phase is synthesized, suitable for ligand exchange chromatography, and L-proline is chemically bonded to silica gel via 3-glycidoxypropyltrimethoxysilane.
Abstract: A method for the direct separation of racemates by HPLC is described. A chiral stationary phase is synthesized, suitable for ligand exchange chromatography. L-proline is chemically bonded to silica gel via 3-glycidoxypropyltrimethoxysilane. The bonded support is loaded with Cu(II) ions as a complexing agent. Complete resolution of amino acid racemates can be obtained in less than ten minutes. α-values up to 3.5 are observed.
TL;DR: In this article, neutral oligosaccharides derived from dolichol-linked intermediates have been separated by liquid chromatography on silica gel modified by organic amines.
TL;DR: In this paper, it is shown that metal traces in high-performance liquid chromatographic bonded-phase silica gel interfere with some separations, and a test for such activity, based on the chromatography of beer bitter acids, is described.
TL;DR: In this paper, column switching techniques were applied to the isocratic analysis of gasolines, light and heavy gas oils and solvent refined coal using a microprocessor-based liquid chromatograph with time-programmable events.
TL;DR: In this article, a gaschromatographische bestimmung of 11 herbiciden Phenoxyalkancarbonsauren and deren Ester und Konjugate in Pflanzenmaterial beschrieben.
Abstract: Es wird eine Methode fur die gaschromatographische Bestimmung von 11 herbiciden Phenoxyalkancarbonsauren sowie deren Ester und Konjugate in Pflanzenmaterial beschrieben. Nach alkalischer Hydrolyse werden die Sauren aus dem angesauerten Hydrolysat durch Aceton/Wasser/Dichlormethan-Verteilung extrahiert. Der Extrakt wird uber Gel-Chromatographie an Bio Beads S-X3 und eine Saure/Base-Ausschuttelung gereinigt. Die Sauren werden mit Methanol/Schwefelsaure verestert. Die gaschromatographische Bestimmung erfolgt massenfragmentographisch als Methylester. 2,4-D, 2,4-DB, Dichlorprop, Diclofop-methyl, Fenoprop und 2,4,5-T konnen gas-chromatographisch auch mit dem Elektroneneinfangdetektor bestimmt werden, wenn die Methylesterlosungen an einer Mini-Kieselgel-Saule nachgereinigt werden.
TL;DR: In this paper, a reversed-phase liquid chromatogrphic approach using dynamically coated stationary phases has been investigated, with silica gel as the solid phase and a mobile phase consisting of a buffer in the pH range 5-9, with a long-chain quaternary ammonium compound added as the reversed phase-forming agent.
TL;DR: The study was carried out partly to assess the performance of the combined technique, and results obtained indicate that it is highly promising as a method to determined protein molecular weight both accurately and quickly.
Abstract: Molecular weight of Aspergillus oryzae alpha-amylase (Taka-amylase A) was estimated to be 51,000 +/- 500 by the combined use of high pressure silica gel (TSK-GEL G3000SW) chromatography and the low angle laser light scattering technique. The study was carried out partly to assess the performance of the combined technique, and results obtained indicate that it is highly promising as a method to determined protein molecular weight both accurately and quickly.
TL;DR: The surface properties of complex adsorbents prepared through the pyrolysis of dichloromethane on the surface of silica gel were investigated in this article, where the reaction was carried out in a specially constructed reactor at 400-500°C.
Abstract: The surface properties of complex adsorbents prepared through the pyrolysis of dichloromethane on the surface of silica gel were investigated. The reaction was carried out in a specially constructed reactor at 400–500°C. The construction and performance of the reactor are described. The modification of the silica gel surface by pyrogenic carbon results in its chemical but not energetical homogeneity. Such adsorbents usually show strong adsorptive properties which limits their use in chromatography. A simple method of homogenizing the porous structure and energetic properties of the adsorptive centers of such adsorbents is presented. The method consists of an additional pyrolysis of an alcohol or other substances on the surface of the carbon-silica adsorbent. Such reactions were carried out under both static and dynamic conditions. The properties of the modified adsorbent depend on the reaction conditions and on the type of the additionally pyrolysed substance.
TL;DR: In this article, photoacoustic spectroscopy and solid-solution distribution measurements are used to study complexation of copper(II) with N-2-aminoethyl-3-aminopropyltrimethoxysilane immobilized on silica gel.
Patent•
04 Sep 1981TL;DR: In this article, novel metal chelating agents which are bonded to inorganic substrates to immobilize them are disclosed. But the authors do not discuss the properties of these agents in detail.
Abstract: What is disclosed are novel metal chelating agents which are bonded to inorganic substrates to immobilize them. An example of such a metal chelating agent is (CH3 O)3 Si(CH2)3 NH(CH2 CH2 NH)2 (CH2)3 Si(OCH3). An example of an inorganic substrate is a silica gel.
TL;DR: Evidence is presented that, at least for HI-6, the addition of counter ions to the system does not lead to the formation of ion pairs to be retained by partition, but rather to a mechanism based on adsorption chromatography.
TL;DR: In this paper, a method for the rapid catalytic hydrolysis of phenylurea herbicides on silica gel at elevated temperatures is described, which has successfully been applied to residue analysis of water samples at the 1 ppb level.
Abstract: A method is described for the rapid catalytic hydrolysis of phenylurea herbicides on silica gel at elevated temperatures. After derivatisation of the anilines produced with heptafluorobutyric acid anhydride final analysis is done on a gas chromatograph equipped with an electroncapture detector. Detection limits are in the 1–5 picogram range. The method has successfully been applied to residue analysis of water samples at the 1 ppb level. The determination of free anilines present in water samples and the potential of various techniques to be used to discriminate between free anilines and parent herbicides are also discussed.
TL;DR: In this paper, the volatile components of apricot variety "Rouge du Roussillon" were isolated by vacuum distillation and fractionated on silica gel.
Abstract: The volatile components of apricot variety “Rouge du Roussillon” were isolated by vacuum distillation and fractionated on silica gel. Analysis by combined gas chromatography-mass spectrometry led to identification of several compounds identified for the first time from this product. These compounds included p-hydroxybenzaldehyde, p-methoxybenzaldehyde, (3-phenyl propyl)-propyl or isopropyl ketone, 3-nonene-2-one, damascenone, β-ionone, dihydroactinidiolide, 2-phenylethanol, cis rose oxide and nerol oxide. The formation mechanism of these compounds is envisaged. Fractions isolated by chromatography on silica gel and head space concentration on Chromosorb 105 were sniffed and analyzed by gaz chromatography. The results obtained indicate that aroma of apricot is due to the presence of compounds such as benzaldehyde, linalool, 4-terpinenol, α-terpineol and perphaps 2-phenylethanol which are responsable for the floral and fruity part of the aroma. Lactones previously identified are “background” compounds as in Cling peach.