Silica Gel Thin-layer Plates Research Articles

The reversed phase thin-layer chromatographic behavior of the rare earths, thorium, uranium and zirconuim with a high molecular weight amine in sulfuric acid and ammonium sulfate systems

Thin-layer plates of silica gel impregnated with a high molecular weight amine Amberlite LA-2, in the sulfate form, were used to investigate systematically the chromatographic behavior of the rare earths thorium, uranium(VI) and zirconium in sulfuric acid and acid ammonium sulfate media. The R F values for these metal ions decrease with increasing concentration of the acid sulfate, in teh acid system particularly. An interesting correlation is revealed between the R F values of the rare earths and the paramagnetic moment of the trivalent rare earths in the high concentration range of the acid and sulfate. An odd—even fluctuation of the R F values against atomic number is also found for the heavy lanthanides. Differences in the R F values of the rare earths in acid sulfate media indicate teh possibility of good separations of adjacent pairs or groups of the rare earths from each other by selecting an appropriate concentration of sulfate. The rare earths, thorium, uranium(VI) and zirconium can also be separated chromatographically with either 0.5 or 1.0 M sulfuric acid as developing solvent.

An improved method for rapid, large-scale thin-layer chromatographic urine screening for drugs of abuse

This report describes a rapid, reliable, thin-layer chromatographic screening method, suitable for large scale operations, for the detection of drug abuse. By utilizing microdot sample application on 100 mμ thin-layer silica gel plates, sample size has been diminished with an increase in sensitivity. Drugs are detected using a separate series of chromophoric spray reagents for the acid and basic drugs, including a new reagent N,2,6-trichlorobenzoquinoneimine for the visualization of cyclic imide type compounds (barbiturates). Confirmation of drug identification to eliminate false positive results, is achieved, using the technique of microcrystallography.

Routine identification of drugs of abuse in human urine : I. Application of fluorometry, thin-layer and gas—liquid chromatography

The methods described in this report were developed for the rapid analysis of over 500 urines per day for psychoactive drugs. These techniques involve extraction of the drugs from biological material, scanning the extract by automated spectro-fluorometry, extensive use of thin-layer chromatography coupled with sequential chromogenic spraying and application of gas—liquid chromatography as an adjunct method for positive identification and confirmation. The urinalysis laboratory requires a 50–60 ml sample from which a 2 ml aliquot is subjected to fluorometric analysis. The positive morphine and/or quinine samples were then acid hydrolyzed, extracted at pH 9 and the extracts applied to thin-layer plates and the presence of morphine and quinine confirmed by R F values and reactions with specific chromogenic spray reagents. A 15 ml aliquot of the urine was extracted at pH < 1 for barbiturates, diphenylhydantoin and glutethimide. The extract was applied to chromagram sheets developed and sprayed with reagents that provide reactions with these acidic drugs. A 25 ml aliquot of the urine was extracted at pH 10–11 for opiates, opioids, amphetamines, phenothiazines and tranquilizers. The organic extract was divided into A and B fractions, and these fractions developed on separate thin-layer silica gel plates. The A fraction was sprayed with chromogenic reagents primarily to detect amphetamine and analogues. The B fraction was sprayed with reagents to detect opiates, opioids, tranquilizers and phenothiazines. However, the reactions and R F values on the A and B plates were usually cross compared for the various drugs of abuse. The methods and techniques were relatively simple to perform and the psychoactive drugs could be detected in the range of 1 to 5 μg/ml of urine.

Determination of Phenoxymethyl Penicilloic Acid and Phenoxyethyl Penicilloic Acid in Urine in the Presence of the Parent Penicillins

Penicillin and the corresponding penicilloic acid are extracted by chloroform from an acidified sample of urine which has been partly saturated by ammonium sulfate. A portion of the extract is dried and redissolved in a small volume of acetone. A measured aliquot is chromatographed on a silica gel thin-layer plate by acetone-acetic acid (19:1). The separated penicilloic acid is detected by starch-iodine spraying. The zones are transferred into glass tubes, nitrated, and neutralized by ammonia. The absorbance of the yellow supernatant, which is proportional to the concentration of penicilloic acid, is measured spectrophtometrically.

Thin Layer Chromatographic Separation and Chromogenic Detection of Diazinon and Some of Its Known or Suspected Metabolites and/or Degradation Products

Abstract Diazinon and 5 of its known or suspected transformation products were chromatographed on thin layer sheets and thin layer silica gel plates, using a variety of solvents. Ten chromogenic sprays with sensitivity ranges from 0.05 to 1 μg were used to identify the migrated compounds on the thin layer chromatogram. Two-dimensional TLC separated all the compounds in a single procedure. Several crops fortified at levels of 0.5 to 2.0 ppm were successfully analyzed for these compounds.

Characterization of the Steam Nonvolatile Residue of Bergamot Oil and Some Other Essential Oils

Abstract A method is presented for identifying and estimating the coumarins and furocoumarins present in bergamot oil and four other essential oils. Solutions of the nonvolatile residue of the oils are spotted on silica gel thin layer plates and developed in hexane-ethyl acetate (75+25) for 4 hr. The separated compounds are identified by their Rf values and characteristic fluorescence under short wave UV light; the spots are marked, scraped from the plate, and extracted with chloroform. The centrifuged extracts are scanned in a recording spectrophotometer from 400 to 240 mμ. Bergaptene, citroptene, bergamottin, and 7-methoxy-5-geranoxycoumarin were also individually estimated. Bergaptol, isopimpinellin, and xanthotoxin could be estimated only roughly because of low absorbance readings or lack of standards. A procedure to isolate and purify bergamottin from bergamot oil and 7-methoxy-5-geranoxycoumarin from lime oil, to serve as reference standards, is also included.

Transformation of aflatoxin B1 by steroid-hydroxylating fungi

Numerous organisms were examined to find a fungal system capable of catalyzing aflatoxin transformations. Some fungi, particularly Dactylium dendroides, Absidia repens, and Mucor griseo-cyanus, transform about 50–60% of aflatoxin B1 in shake cultures to a new fluorescent-blue compound (R0), with a lower Rf (0.57) than B1 (0.69) on silica gel thin-layer chromatographic plates (acetone:CHCl3, 20:80). In a separate assay, washed fungal mycelium suspended in 0.02 M PO4 buffer catalyzed a 25–30% conversion in 20 h. The new fluorescent compound was separated from the unchanged B1 by column chromatography on silica gel G with washed CHCl3 containing 6% acetone and 0.75% ETOH as solvent. The ultraviolet spectrum showed maxima of 325, 261, and 254 mμ. Its infrared spectrum, showing a shift in absorption peaks at 1760 and 1685 cm−1, indicated a change in the functional carbonyls of B1; in addition, a broad band at 3400 cm−1 indicated a hydroxylated compound.

Indoxyl Acetate Spray Reagent for Fluorogenic Detection of Cholinesterase Inhibitors in Environmental Samples

Abstract A cholinesterase inhibition method to detect ihionophosphates (P=S compounds) and their oxygen analogs (P=O) by twodimensional thin layer chromatography is described. Environmental samples are cleaned up on Florex columns and spotted on silica gel thin layer plates. Plates are developed in solvent mixtures of opposite polarity, then sprayed with an enzyme solution and indoxyl acetate. Submicrogram sensitivity is achieved by fluorogenic and chromogenic reaction. Some compounds give characteristic colored reaction products.

Nutrition of Threonine

The threonine content in blood and urine increased and threonine decomposition ability in liver decreased by feeding lower level of lysine, whereas threonine content in blood and urine decreased and the ability of liver increased gradually with increasing lysine content in diet. These phenomena were owing to the increase of threonine dehydratase activity of liver, which was measured from produced α-ketobutyric acid amount, by excess administration of lysine. The phenomena that threonine content in urine decreased and threonine decomposition ability of liver increased with increasing threonine content in diet when adequate amount of lysine was fed, were also ascribed to the increase of the dehydratase activity.One m mole of threonine was incubated with liver homogenate in presence of PALP*** at pH 8.2 for 20 and 30 min and α-ketobutyric acid produced was introduced to its 2,4-dinitrophenylhydrazone, which was chromatographed on silica-gel thin-layer plate and determined spectrophotometrically at 395 mμ und...

Fluorometrische bestimmung von porphyrinmethylestern im dünnschichtchromatogramm

A fluorometric determination of porphyrin methyl esters by scanning of pre-coated silica gel thin-layer plates is described. For the measurement a Vitatron UFD photometer with densitometer arrangement is used.

Origin of some derivatives of retinoic acid found in rat bile

After the intraportal injection of retinoic acid-15-(14)C into rats, all-trans methyl retinoate, a cis isomer of methyl retinoate, retinoyl beta-glucurono-gamma-lactone, retinoic acid, and retinoyl beta-glucuronide were isolated from methanol extracts of rat bile by chromatography on anion-exchange resin and silicic acid columns and characterized on thin-layer plates of Silica Gel G. On the other hand, when bile was extracted with n-butanol or analyzed directly by thin-layer chromatography, only retinoyl beta-glucuronide and a very small amount of retinoic acid could be detected. Butanol extracts of the liver and the intestine, however, still contained a small radioactive nonpolar fraction. When retinoyl beta-glucuronide was incubated with an anion-exchange resin in the presence of methanol, several nonpolar products appeared. Apparently the methyl retinoate, retinoyl beta-glucurono-gamma-lactone, and most of the retinoic acid previously found in bile after retinoic acid administration are produced from retinoyl beta-glucuronide during the isolation procedure.

Decomposition of 17α-ethynylestradiol and its ethers on silver nitrate impregnated silica gel thin layer plates

Chromatography of small amounts of radioactive 17α-thynylestradiol and its 3-methyl and 3-cyclopentyl ethers on silver nitrate impregnated thin layer silica gel plates resulted in decomposition of the compounds. Estrone and estrone 3-methyl ether were identified as decomposition products of 17α-ethynylestradiol and 17α-ethynylestradiol 3-methyl ether respectively.

TLC Spotting Solvent for Aflatoxins

Abstract Benzene is recommended as a spotting solvent for aflatoxins on silica gel thin layer plates in preference to chloroform. Based on a 12-month study of stability and practical application, aflatoxin in benzene was as stable as in chloroform; benzene was less volatile, helping insure volume integrity, and easier to manipulate than chloroform. Spots on thin layer chromatograms were more compact and uniform when dispensed from benzene than from chloroform.

The isolation and characterisation of phosphatidylglycerol and a structural isomer from pig lung

Two minor phospholipid components were isolated from a lipid extract of pig lungs. One was identified as phosphatidylglycerol. The results of alkaline hydrolysis, periodate oxidation and acetolysis showed that the other was a structural isomer of phosphatidylglycerol with the structure of a lyso- bis-phosphatidic acid. Its chromatographic characteristics on thin-layer plates of silica gel and on silicic acid-impregnated paper were quite distinct from those of phosphatidylglycerol. Both of these phospholipids were also present in lipid extracts of rat lungs and rabbit lungs.

Qualitative and quantitative determination of mixtures of amino acids using 2,4,6-trinitrobenzenesulfonic acid

Mixtures of TNP-amino acids may be rapidly resolved by chromatography on thin-layer plates of silica gel. The colored derivatives can be quantitated spectrophotometrically following elution from the plates. The advantages of this method lie in its rapidity and the modest equipment needed.

Photochemical Changes of Aflatoxin B1

Abstract Irradiation of aflatoxins B1 and G1 with UV light (principal wavelength 𝀈365 mμ) converts both compounds to new fluorescent photoproducts which have much lower R1 values than aflatoxin B1 and G1 when chromatographed on silica gel thin layer plates. Photoproducts of aflatoxin B1 form much faster on a silica gel surface than in methanol solution. Photoconversion of aflatoxin B1 is shown to alter fluorescence comparison assays and identification tests. Studies show that the principal photoproduct developed from aflatoxin B1 is significantly less toxic than the parent aflatoxin.

Separation of acidic phospholipids by one-dimensional thin-layer chromatography

1. 1. Three one-dimensional thin-layer Chromatographie systems for separation of acidic phospholipids such as cardiolipin, phosphatidic acid and phosphatidyl-glycerol, are described. System I: adsorbent is silica gel without CaSO 4 binder. Two step developing system is used. The first solvent is acetone-light petroleum (1:3, by vol.); the second solvent is a mixture of chloroform-methanol-acetic acid-water (80:13:8:0.3, by vol.). The separated compounds from the top of the chromatogram are: monoglyceride, cardiolipin, phosphatidic acid, ceramidemonohexosides (cerebrosides), phosphatidylglycerol and phosphatidylethanolamine. System II: silica gel thin-layer plates are prepared with 0.1 M Na 2CO 3. The first solvent is pyridine-light petroleum (3:1, by vol.); the second solvent is chloroform-methanol-pyridine-2 M NH 4OH (35:12:65:1, by vol.). The following compounds are separated by the two-step developing system (from the top of chromatogram): ceramidemonohexosides, sulfatides and ceramidedihexosides (overlapping), phosphatidic acid, phosphatidylglycerol and cardiolipin. System III: one-step development modification of System II. This system is suitable only for quantitative determination of phospholipids if the presence of glycolipids is not deemed detrimental. 2. 2. Application of the Systems I and II for separation of acidic phospholipids along with some glycolipids is demonstrated on total lipid extracts from animal tissues. 3. 3. The systems described for the separation of acidic phospholipids are complementary to the previously reported system for separation of phospholipids.

A thin-layer chromatographic method for the rapid separation of porphyrin dimethyl esters

The addition of iron salts to thin-layer plates of Silica Gel G was found to facilitate the separation of porphyrin dimethyl esters so greatly that rapid separation in one dimension and in one solvent system could be carried out. A somewhat similar result, although not so marked, was also observed with iron-impregnated paper. It was shown that pH adjustment of the medium by addition of mineral acid alone, to the value resulting from iron-salt hydrolysis in the medium, will not duplicate the effect. Addition of Cu, Mn or Mg to Silica Gel G was ineffective.

Nutrition of Threonine

The threonine content in blood and urine increased and threonine decomposition ability in liver decreased by feeding lower level of lysine, whereas threonine content in blood and urine decreased and the ability of liver increased gradually with increasing lysine content in diet. These phenomena were owing to the increase of threonine dehydratase activity of liver, which was measured from produced α-ketobutyric acid amount, by excess administration of lysine. The phenomena that threonine content in urine decreased and threonine decomposition ability of liver increased with increasing threonine content in diet when adequate amount of lysine was fed, were also ascribed to the increase of the dehydratase activity. One m mole of threonine was incubated with liver homogenate in presence of PALP*** at pH 8.2 for 20 and 30min and α-ketobutyric acid produced was introduced to its 2, 4-dinitrophenylhydrazone, which was chromatographed on silica-gel thin-layer plate and determined spectrophotometrically at 395mμ under N, N-dimethylformamide. Other enzyme systems relating to threonine catabolism were also investigated, including threonine aldolase, threonine dehydrogenase and ornithine transaminase, showing no significant changes in activities by excess administration of lysine and/or threonine.

Triglyceride biosynthesis in the intestinal mucosa

1. 1. The chemical type of triglyceride synthesized by the enzymes of the hamster intestinal mucosa from monoglycerides and fatty acids have been examined employing AgNO 3-impregnated silica-gel thin-layer plates. 2. 2. When 2-monopalmitin and palmityl-CoA or oleyl-CoA or the combination of the CoA thioesters of the fatty acids were employed, a close-to-theoretical distribution of the fatty acids in the synthesized triglycerides was obtained. 3. 3. When the free fatty acids and an activating system were substituted for the CoA derivatives a preferential utilization of palmitic acid was observed. 4. 4. The relationship of the reported findings to the overall absorption of triglyceride is discussed.