Impregnated Silica Gel Research Articles

Identification of Some Potential Antidiabetic Compounds on Impregnated Silica Gel G Platea as Their π-Complexes

Abstract A rapid and convenient procedure for the detection of potential antidiabetics as π complexes with aromatic amines is described. The method could be of immense value even in places where normal laboratory facilities are not available.

Chromatography of Amino Acids on Reversed Phase Thin Layer Plates

Abstract The separation of 19 amino acids was studied on reversed phase thin layers, including C18 chemically bonded silica gel, impregnated silica gel, and acetylated cellulose. Normal aqueous-organic solvents, aqueous micellar solutions, and reversed micellar solutions were tested as mobile phases. The only practical system that provided a reversal in migration sequence compared to silica gel and cellulose included a C18 layer impregnated with HDBS, and this reversal was apparently due to an ion exchange mechanism.

Vacuum pyrolysis of Recent sedimentary humic acids and kerogens.

Humic acid and kerogen samples isolated from some Recent sediments of different environments were analyzed by vacuum pyrolysis to characterize their chemical nature. The samples were pyrolysed at 500°C in vacuo (about 10-2 Torr.). Gravimetric and elemental analyses of the pyrolysis residue indicated that the pyrolytic degradation resulted in the loss of carbon and nitrogen in the range of 35–53% and 53–68%, respectively. The pyrolysate was trapped and extracted with chloroform. It was fractionated using silica gel and Ag+-impregnated silica gel column chromatography. Subsequent gas chromatographic analyses enabled quantification of n-alkane and n-alkene homologues. Generated straight-chain hydrocarbons (≥C14) amounted to about 1–4mg per g carbon in the humic acids and to about 2–20mg per g carbon in the kerogens. The potential of the technique to characterize the chemical nature of the humic materials is discussed.

Detection of palm oil in vanaspati by thin layer chromatography

AbstractPalm oil (raw or refined), as such, or the unsaponifiable matter of palm oil and vanaspati (mostly hydrogenated soybean oil containing 5% sesame oil), when separated on a silver nitrate impregnated Silica Gel G plate or a Silica Gel G plate using (a) hexane/ether/acetic acid (80:20:1.5) or (b) chloroform, respectively, for development showed distinct differences. On the basis of this, two systems have been suggested for the detection of palm oil in vanaspati. About 5% adulteration can be detected by the first method and 10% by the second.

Synthesis and purification of the allofarnesenes

The eight isomers of allofarnesene (3,7,11-trimethyl-2,4,6,10-dodecatetraene) were prepared using Wittig reactions. The four E-4 isomers could be separated using GC but the unstable Z-A isomers required HPLC on silver nitrate impregnated silica gel for analysis. Purified samples of each isomer were prepared for spectral studies. The configuration of the pseudoionone (6,10-dimethyl-3,5,9-undecatriene-2-one) starting materials was also studied, confirming previous results.

42] Thin layer—gas chromatographic determination of 25-hydroxycholecalciferol

Publisher Summary This chapter explains thin layer-gas chromatographic determination of 25‑hydroxycholecalciferol. The 25-hydroxycholecalciferol (25-HCC) is formed from cholcalciferol in the liver and undergoes further hydroxylation to 1,25-dihydroxycholecalciferol, the active metabolite of cholecalciferol, in the kidney. In the method discussed in this chapter, determination of 25-HCC is achieved by gas chromatography (GC) after saponification and thin layer chromatography (TLC). Separation from other unsaponifiable materials, such as cholesterol, which are present in amounts manifold greater then 25-HCC in physiological samples, is critical in obtaining a clean GC determination. Direct GC of 25-HCC results in formation of the iso and pyro ring closure compounds having different retention times. A single peak, however, is obtained after formation of the trifluoroacetate. For preparing the sample for TLC, samples should be dispersed, or homogenized, in ethanol containing 50 mg pyrogallol, such that the ratio of solvent to sample is approximately 10:1. As 25-HCC is sensitive to both UV light and to oxygen, the procedure in this study was carried out as much as possible in a darkened room. Alternative developing solvents systems for the TLC plate were examined. Using AgNO 3 -impregnated silica gel, 25-HCC was also separated well from major unsaponifiable materials other than retinol.

Glycosides of marine invertebrates—VI. Steroid glycosides from holothurian Stichopus japonicus

1. 1. Steroid glycosides from holothurian Stichopus japonicus Selenka were investigated. The β-monoside fraction has been isolated by chromatography on silica gel columns with subsequent preparative thin-layer chromatography on a fixed silica gel layer. 2. 2. Hydrolytic products of the isolated glycosides were examined by gas chromatography, paper chromatography, silver nitrate impregnated silica gel column chromatography, infrared absorption and nuclear magnetic resonance spectrometries. 3. 3. It was shown that aglycones of these glycosides are C 26, C 27, C 28 and C 29-sterols with saturated and monounsaturated nucleus. The double bond in the steroidal nucleus is located at C(7)-C(8). A side chain contains a double bond at C(22)-C(23) or C(24)-C(28). The monosaccharide proved to be d-xylose. 4. 4. Similar glycosides were identified in holothurians Isostichopus hadionotus, Synapta lappa and other species.

Constituents of cannabis sativa L. An improved method for the synthesis of dl‐cannabichromene

AbstractA new procedure was developed for the synthesis of cannabichromene (III) which involves reflux of equimolar amounts of olivetol (I), citral (II) and t‐butylamine in toluene for 9 hours. The purification of III was best achieved by sodium borohydride reduction of unreacted II followed by column chromatography on 1% sodium hydroxide impregnated silica gel 60‐PF. The yield of III (62.0%) was much higher than that reported in the literature.

Thin-Layer Chromatography of Some Toxic Alkaloids on Metal Salt Impregnated Silica Gel and Alumina Layers

Thin-Layer Chromatography of Some Toxic Alkaloids on Metal Salt Impregnated Silica Gel and Alumina Layers

2-Mercaptobenzothiazole Supported on Silica Gel for the Chromatographic Concentration of Cadmium, Copper, Lead, and Zinc in Natural Water Samples

Abstract The preparation and characteristics of 2-mercaptobenzothiazole supported on silica gel (MBT–SG), and its application to the preconcentration and determination of cadmium, copper, lead, and zinc in natural water samples are described. The MBT–SG was prepared by impregnating silica gel with MBT in a dioxane–methyl acetate solvent mixture, drying, washing with deionized water, and finally drying. The chelating capacity of the material was 0.01 meq. Cu/g. Cadmium, copper, lead, and zinc were quantitatively retained on the MBT–SG at pH values of 4.8, 2.5, 4.8, and 6.5 for an aqueous solution, and at pH values of 4.8, 2.8, 4.8, and 6.5 for sea water. A column made of the material provided quantitative recovery of these metals from natural water samples at higher flow rates (2–5 1/h) than other chelating resins, e. g., chelex 100. Cadmium was eluted with hydrochloric acid (1 : 99), copper and lead with acetone–hydrochloric acid mixture (9 : 1), and zinc with an acetate–hydrochloric acid buffer solution (pH 4.0). Then, the quantities of the four metals in their effluents were determined by atomic absorption spectrometry.

The Use of Sodium Borate Impregnated Silica Gel Plates for the Separation of 3-0-Methyl Catecholamines from Their Corresponding Catecholamines

The use of sodium borate impregnated silica gel plates for the chromatographic separation of the catecholamines noradrenaline, adrenaline, and isoprenaline from their respective 3-0-methylated derivatives, normetanephrine, metanephrine, and methoxy-isoprenaline, is described. The parent catecholamines remain at the origin of the plates while the 3-0-methylated derivatives concentrate in discrete bands at the upper edge of the borate impregnated area (the "borate front").

Formamid-imprägnierung von kieselgelschichten über die gasphase

Impregnation of silica gel layers by formamide in the gas phase For good separations by gradient thin-layer chromatography the necessity of a minimal impregnation rate of 70% has become evident. The most evenly impregnated silica gel layers of laboratory-made or prefabricated products can be obtained by application of formamide or N,N-dimethylformamide in the gas phase. Layers with a defined impregnation rate can be obtained according to the corresponding adsorption and desorption curves. Examples of separations of mixtures of phenols and of cannabinoids illustrate the advantages of silica gel layers impregnated with formamide.

Biosynthesis of hydroxyfatty acid polymers: Enzymatic epoxidation of 18-hydroxyoleic acid to 18-hydroxy- cis-9,10-epoxystearic acid by a particulate preparation from spinach ( Spinacia oleracea)

The major component of the cuticular hydroxyfatty acid polymer, cutin, of spinach leaf was identified as 18-hydroxy- cis-9,10-epoxystearic acid. A 3000 g particulate fraction obtained from the homogenates of young spinach leaves catalyzed the epoxidation of 18-hydroxyoleic acid to 18-hydroxy- cis-9,10-epoxystearic acid. The epoxy acid was identified by thin-layer chromatography of the product of hydration of the oxirane function and subsequent reduction (octadecane-1,9,10,18-tetraol), on silica gel G and boric acid impregnated silica gel, and by radio gas-liquid chromatography of the periodate oxidation product of the tetraol derived from the epoxy acid. This enzymatic epoxidation required ATP, CoA, NADPH, and O 2 for maximal activity. The pH optimum for epoxidation was 9.0, and the epoxidase activity was located mainly in the 3000 g particulate fraction, which contained the cuticular membranes. The rate of epoxidation of the unsaturated acid was linear up to 2 h and up to a protein concentration of 1.5 mg/ml. The apparent K m and V of the enzyme was 7.5 × 10 −5 m and 180 nmol/1-h-mg protein, respectively. That the epoxidase has a stringent substrate specificity was indicated by the observation that 18-hydroxyelaidic acid, 18-acetoxyoleic acid, and oleic acid were not readily epoxidized by this enzyme preparation. Light reversible inhibition by CO suggested the involvement of cytochrome P-450 in the epoxidation. Chelators inhibited epoxidation, and this inhibition was reversed by FeSO 4. The epoxidase was inhibited 30% by 0.5 m m NaCN, whereas the same concentration of NaN 3 showed very little inhibition. The present epoxidase is unique in that it is associated with the 3000 g particles which contain the cutin polymer and in that it requires activation of the carboxyl group distal to the epoxidation site. Enzyme preparations capable of epoxidizing 18-hydroxyoleic acid were also obtained from the skin of apple fruit and from the epidermis of Senecio odoris leaves. This is the first report on an enzyme involved in the biosynthesis of the C 18 family of cutin monomer acids.

Charge transfer thin-layer chromatography and multiple site complexation

The effect of impregnating silica gel with different types of acceptors on the separation of different aromatic hydrocarbons by thin-layer chromatography has been investigated. Benzoquinone and substituted benzoquinones were studied in detail, and it was found that benzoquinone was most sensitive to moderate differences in the structure of most aromatic hydrocarbons. Benzoquinone-impregnated silica gel thin-layer chromatographic R f values were measured for a number of aromatic hydrocarbons, and the “binding constant” of Harvey and Halonen calculated for these hydrocarbons. The question of multiple site complexation between the aromatic hydrocarbon and either the silica gel surface or the benzoquinone was studied extensively. The R F values for the biphenyl-terphenyl-quaterphenyl series appears to give some evidence for some type of multiple site binding. A novel method of locating spots on impregnated silica gel adsorbent has also been devised. It involves spraying with a dilute naphthacene solution; the yellow fluorescence of naphthacene is quenched everywhere except on the spots.

Separation of prostaglandins A, B and C by thin-layer chromatography on ferric chloride impregnated silica gel

Investigation of the in vivo metabolism of PGA 1 requires the availability of satisfactory methodology for the separation and recovery of the isomeric prostaglandins A 1, B 1 and C 1. A convenient and efficient method for the separation of prostaglandins A, B and C based on thin-layer chromatography on ferric chloride impregnated silica gel has been developed. The resolution of Prostaglandin A from Prostaglandin B was far superior to that on silica gel thinlayer chromatography plates impregnated with silver nitrate. The conditions for satisfactory recovery of PGA 1 from the ferric chloride impregnated silica gel adsorbent have been established.

The triglyceride composition of Corchorus olitorius seed oil.

AbstractCorchorus olitorius seed oil and its randomised product have been subjected to pancreatic hydrolysis. Glyceride compositions have been calculated from the original fatty acid composition and those of the monoglycerides produced by hydrolysis. The percent GS3 content of the seed oil and of its interesterified product have also been determined by the combined techniques of thin layer chromatography on silver nitrate impregnated silica gel and colorimetry.

Thin-layer chromatography of aromatic amines on cadmium acetate impregnated silica gel thin layers

Thin-layer chromatography of aromatic amines on cadmium acetate impregnated silica gel thin layers

Triglyceride Composition of Milk Fat: II. Separation of Triglycerides by Argentation-TLC and GLC

Fractions of milk fat separated by column chromatography on silicic acid were further analyzed by thin-layer chromatography on silver nitrate impregnated silica gel and gas chromatography of triglycerides and their component fatty acids. The triglyceride types in 8 bands on the thin-layer chromatograms were characterized and their composition determined.

The triglyceride composition ofMoringa concanensis seed fat

AbstractMoringa concanensis seed fat and its randomized product have been subjected to pancreatic hydrolysis. Glyceride compositions have been calculated from the original fatty acid composition and those of the monoglycerides produced by hydrolysis. The per cent GS3 content of the interesterified product has also been determined by the combined techniques of thin layer chromatography on silver nitrate impregnated silica gel and colorimetry.

Group separation of Δ4-3-oxosteroids and Δ5-3 β-hydroxysteroids by chromatography on digitonin-silica thin layers

A convenient method is presented for the complete separation of Δ 4-3-oxosteroids and Δ 5-3 β-hydroxysteroids by chromatography on digitonin impregnated silica gel thin layers. Its properties are: 1. (1) All Δ 4-3-oxosteroids run as a group, R f = 0.86. 2. (2) The R f of an individual Δ 5-3 β-hydroxysteroids depends on its structure. 3. (3) The R f of an individual Δ 5-3 β-hydroxysteroid depends also on the amount of the Δ 5-3 β-hydroxysteroid present—increasing mass decreases its r f . 4. (4) There exists a “cooperative effect” whereby it is the total mass of all Δ 5-3 β-hydroxysteroids present which determines the collective R f of the group. 5. (5) Complete separation of Δ 4-3-oxosteroids is possible providing a minimum 1.0 μg total mass of Δ 5-3 β-hydroxysteroids is present. 6. (6) The common “estrogens” and probably all 3α-hydroxysteroids behave as Δ 4-3-oxosteroids.