Silica Gel Sheets Research Articles

Identification of Street Drugs by Thin-Layer Chromatography and a Single Visualization Reagent

TCBI has been shown to be an extremely sensitive visualizer that gives a wide variety of colors with the drugs of abuse. The combination of TCBI as a visualization reagent and manual TLC, using flexible silica gel sheets, can provide a rapid means for the preliminary identification of street drugs.

A Portable Explosives Identification Kit for Field Use

This study has shown the feasibility of using a miniaturized TLC kit for the presumptive identification of explosives in the field. The process of TLC field screening of a post-explosion site is nondestructive, resolves constituent explosives from interfering backgrounds, and increases the residence time of isolated specimens in the adsorbed state for subsequent substantive identification by trace methods of instrumental analyses. The cost of the modified Kodak kit for explosives identification (excluding the microscope) is approximately +150. The stock items, such as the fluorescent silica gel sheets, Cab-O-Sil, and solvents, are of nominal cost. The kit is relatively simple to use and personnel with a minimal technical background can be trained in its use.

Corticosteroids in premature cord blood determined fluorometrically by enzymatic reduction of cortisone.

ABSTRACT Cortisol and cortisone were determined in extracts of cord plasma by fluorometric measurement before and after incubation with a guinea pig liver microsomal enzyme preparation which reduced cortisone to cortisol. Plasma samples were extracted with CH2C12 after a wash with hexane and extraction with CCl4. TLC on silica gel sheets developed in toluene:chloroform:methanol:water (120:60:20:1) was also employed and confirmed results obtained with whole extracts but was not applied generally because of variable and low recoveries upon elution. Values obtained, in μ;g/100 ml plasma, for infants of 38–42 weeks gestational age were: cortisol 10.5 ± 1.0; cortisone 20.4 ± 3.4. Values for premature infants 28–36 weeks were: cortisol 16.7 ± 1.5; cortisone 35.3 ± 5.7. These findings are consistent with the thesis that corticosteroids play a critical role in parturition, insofar as levels are not less when this occurs prematurely. In this series values for premature infants were higher; it was concluded that mo...

Thin Layer Chromatographic Identification of Crimidine in Animal Stomach Contents in Experimentally Induced Castrix Poisoning

Abstract Crimidine (2-chloro-4-dimethylamino-6-methylpyrimidine), the active ingredient of the rodenticide Castrix, is extracted from animal stomach or gizzard contents with chloroform in an alkaline medium. The extract is used for thin layer chromatography on a silica gel or polyamid sheet containing a fluorescent indicator; water-30% ammonia (100+2) or water-methanol-30% ammonia (80+20+2) is the mobile solvent. After drying, crimidine appears under ultraviolet light as a dark spot on a fluorescent background. Amounts of 5 μg crimidine are clearly visible; the purple-red dye present in Castrix kernels remains on the baseline.

Adsorption chromatography of cyclic nucleotides on silica gel and alumina thin-layer sheets

Several solvent combinations of graded polarity have been developed, capable of separating cAMP or cGMP, not only from related nucleotides but from bases and nucleosides on alumina and silica gel thin-layer sheets (tls). The solvent system chloroform (C), methanol (M), water (W) (40:20:3) gave effective separations of cAMP on silica gel TLS. Identical results were obtained when this adsorption chromatography method was compared with the ion-exchange chromatography method involving PEI for its effectiveness in the separation of [α- 32P]cAMP formed from [α- 32P]ATP by a preparation of bovine sperm cells. In addition, this solvent system effectively separates cAMP from inosine, hypoxanthine, xanthine, and uric acid which may be useful in determinations of cAMP arising from 3H- or 14C-prelabeled ATP. Effective separation of cGMP on silica gel tls was accomplished with C:M:W (30:30:5). On alumina tls, cAMP and cGMP were separated from related compounds with M:W combinations; the solvent M:W (50:50) gave the lowest blanks (0.02%) for cGMP and it may prove useful in cGMP determinations.

Routine identification of cocaine metabolites in human urine

A method was developed whereby the major metabolites of cocaine (ecgonine and benzoylecgonine) were extracted from human urine, butylated and subsequently isolated and identified on Polygram silica gel sheets. A comparison of the butylated ecgonine thin-layer chromatographic technique (BETT) with the enzyme multiplied immunoassay technique (EMIT) for benzoylecgonine indicated complete agreement on the presence or absence of cocaine metabolites in 88% of the human urine samples analyzed. Disagreement on the positive urine samples was ascribed to the lower level of sensitivity of BETT (3–5 μg/ml of ecgonine or benzoylecgonine) in comparison to EMIT (1 μg/ml benzoylecgonine). Of the urine samples positive for the cocaine metabolites 18% were negative for other drugs of abuse and 71% were positive for methadone. Cross-reactivity studies with EMIT indicated a high degree of specificity for benzoylecgonine. The BETT and EMIT assays were found to be highly reliable, valid and sensitive tests for the presence of cocaine metabolites in human urine.

Routine identification of drugs of abuse in human urine : III. Differential elution of the XAD-2 resin

The differential elution of the XAD-2 resin consisted of a sequential solvent extraction of drugs from the resin as follows: after passing the urine over the resin, the columns were transferred to centrifuge tubes containing 0.1 N hydrochloric acid and eluted with 10 ml of isopropyl ether. The tubes were thoroughly shaken and the phases were separated by freezing the aqueous layer pouring off the isopropy. ether. This phase was evaporated to dryness and the residues containing primarily the acidic and neutral drugs were applied to Polygram silica gel sheets and developed in chloroform-methanol-ammonia (90:10:1). The XAD-2 resin columns saved for the second elution were placed on the original centrifuge tubes containing the frozen acidic aqueous phase. The resins were eluted with two 10-ml portions of chloroformisopropanol (3:1). One millilitre of 0.125 M borax solution was added to each tube (pH 8–9.5), it was shaken and the phases were separated. The organic phases were evaporated to dryness and the residues containing primarily the basic and some neutral drugs were applied to silica gel thin-layer plates and developed in ethyl acetate-methanol-water-ammonia (85:10:3:1). The acidic, basic, and neutral drugs were detected by sequential chromogenic spraying of the chromatographic sheets and plates. Total recovery of the barbiturates was about 81% and for the basic drugs, it ranged from about 80 to 100%. The percentage increase in drugs detected with the differential elution technique as compared to the single elution method ranged from 2.4 to 100%. A decrease was observed only with d-propoxyph50%) and phenylpropanolamine (6.2%).

Corticosteroid dynamics in Pacific salmon

The tissue distribution of cortisol- 3H and - 14C and cortisone- 3H and - 14C in sexually mature and orchidectomized male sockeye salmon ( Oncorhynchus nerka) was determined at intervals after a single intraarterial injection of cortisol- 3H and cortisone- 14C. Samples of plasma, blood cells, white muscle, red muscle, liver, kidney, head kidney, spleen, gill, gut, brain, heart and, in some cases, bile, were obtained from gonadectomized fish 10, 20, 40, and 80 min after injection and from mature fish 10, 20, 40, 80, and 160 min after injection. Dichloromethane extracts of the tissues were chromatographed on thin-layer silica gel sheets and the quantity of 3H and 14C chromatographically associated with authentic cortisol and cortisone was determined by double isotope scintillation spectrometry. Cortisol and cortisone radioactivity are expressed as dpm/g tissue for a standard 1-kg fish, as a tissue: plasma ratio and as a cortisol- 3H: cortisone- 3H or cortisone- 14C: cortisol- 14C ratio. In most tisues there was a more rapid clearance of cortisol- 3H in the mature than in the gonadectomized fish. Cortisol- 3H tissue:plasma ratios were generally higher in the mature than in the gonadectomized fish. The cortisol- 3H tissue: plasma ratio was especially high in the kidney, liver, and head kidney of the mature fish. The cortisone- 14C tissue: plasma raitos were also higher in the mature than in the gonadectomized salmon but not so high as the cortisol- 3H ratios, suggesting that there are more binding sites for cortisol than for cortisone. These differences in tissue distribution explain the increase in cortisol and cortisone apparent volume of distribution noted during sexual maturation in earlier plasma clearance studies. Tissue cortisol- 3H: cortisone- 3H ratios indicate an apparent rapid conversion of cortisol to cortisone in spleen, heart, and gills in mature fish and in gut and gills in gonadectomized fish. In the liver of the gonadectomized salmon the cortisol- 3H: cortisone- 3H ratio was high and the cortisone- 14C: cortisol- 14C ratio was low, indicating a predominance of 11 keto-reductase activity. This was not the case in the mature salmon.

Routine identification of drugs of abuse in human urine : II. Development and application of the XAD-2 resin column method

The methods described in this report were developed and applied to the detection of drugs of abuse in human urine in a laboratory analyzing in excess of one thousand urines per day. Routinely 2 ml of urine were analyzed fluorimetrically for morphine and quinine. The positive morphine and/or quinine samples were confirmed by subjecting 15-ml aliquots of urine to acid hydrolysis, extracting and applying the extract to thin-layer chromatograms followed by specific chromogenic spray reagents. 25 ml of urine were applied to polypropylene columns containing 1.1 g of Amberlite XAD-2 resin. The flow rates were controlled with the hydraulic flow control apparatus and the resin eluted with 15 ml chloroform—isopropanol (3:1). The organic solvent extracts were shaken with 1 ml of saturated sodium bicarbonate and the separated organic phases evaporated to dryness in a water bath under a stream of air. The residues were dissolved in methanol and applied equally to silica gel plates and sheets. The plates were developed in ethyl acetate—methanol—water—ammonia (85:10:3:1) and the sheets in chloroform—methanol—ammonia (90:10:1). The plates were sprayed with 0.3% ninhydrin—acid, 5% H 2SO 4, iodoplatinate and p-nitroaniline followed by NaOH. The Polygram sheets were sprayed with 0.4% ninhydrin—acetone, HgSO 4, diphenylcarbazone, NaI and iodoplatinate. The opiates, opioids, barbiturates, amphetamines, phenothiazines, antihistamines and minor tranquilizers were detected by specific color reactions and R F values. The plates and sheets were cross-compared for final interpretation of the results. These methods were unusually simple, extremely rapid, inexpensive and very effective in detecting psychoactive drugs at concentrations ranging from 0.1 to 3 μg/ml of urine.

The thin-layer chromatographic properties of trace metals

The RF-values of two valency states of arsenic in different solvent mixtures on various adsorbents including cellulose plate, commercial precoated cellulose sheet, silica gel plate without binder as well as with plaster of Paris binder and commercial precoated silica gel sheet with polyvinyl alcohol or starch binder are given. The results on cellulose thin-layer are compared with those obtained by paper chromatography using Whatman No. 1 paper. These data together are used in a scheme of graphical representation of RF-values of the whole spots of arsenic (III) and arsenic (V) versus studied adsorbents including paper chromatography. Six different solvent systems for the separation of the two valency states of arsenic are discussed.

The thin-layer chromatographic properties of trace metals II. separation of some cations on commercially precoated sheets

The effect of seven solvent systems on the separation of several metals on commercially precoated cellulose and silica gel sheets was investigated. Suggestions are made for the separation of metals such as Ni, Co, Mn, Cu, Bi, Pb, V(V), and U(VI) in the presence of Zn and Fe(III). Silica gel sheets appear to be very useful for the separation of a number of cations. The detection was carried out with reagents discussed previously 1. Detection limits of o.r to o.r μg per spot were reported. Some of the suggested separation schemes show good promise for further evaluation by in situ diffuse reflectance spectroscopy.

The thin-layer chromatographic properties of trace metals I. Separation of some metals with special reference to lead

The thin-layer chromatographic behaviour of a group of metals has been investigated with various solvent systems on cellulose and silica gel plates and sheets (Eastman Chromagram sheets) by the ascending technique. The results were compared to paper chromatographic separation of the same metals. The cations investigated were Co, Ni, Cu, Bi, Pb, Mn. Cd, V(V), and U(VI). Solvent systems included mixtures of acetone—isopropanol—acetic acid—HCl—water in various combinations and proportions. The separation of lead, which has a strong tendency to tail, was carried out successfully with a solvent mixture of methanol—25 % HNO 3—water (8:1:1). New spray reagents, 4-(2-thiazolylazo)resorcinol, 1-(2-thiazolylazo)-2-naphthol, 4-(2-pyridylazo)resorcinol and 1-(2-pyridylazo)-2-naphthol, were successfully introduced for the detection of the metals as distinctly coloured complexes. Visual detection limits ranged from 0.1 to 0.01 μg per spot.

A simple thin-layer chromatography of cannabinoids by means of silica gel sheets treated with amines

A simple thin-layer chromatography of cannabinoids by means of silica gel sheets treated with amines

Thin-layer chromatographic separation of cystine and the N-ethylmaleimide adducts of cysteine and glutathione

Interest in cystine metabolism related to human cystinuria and cystinosis has lead to increased investigation of cysteine and glutathione formation from cystine by various tissues (1, 2). Advantage has been taken of the extremely rapid and quantitative reaction reported initially by Friedmann et al. (3) and investigated further by others (4–6) in which cysteine and reduced glutathione combine with N-ethylmaleimide (NEM) to form the stable adducts S( N-ethylsuccinimido) cysteine (cysteine-NEM) and S( N-ethylsuccinimido) glutathione (glutathione-NEM), respectively. The use of radioactive substrates has proved to be an extremely sensitive method for detection of these compounds in metabolic studies (1, 7). Presently, however, S( N-ethylsuccinimido) cysteine, S( N-ethylsuccinimido) glutathione, and cystine are separated by lengthy paper chromatography (8–10), by combined ion-exchange chromatography with flow counting through an anthracene-packed cell in a liquid scintillation counter (11), or by high-voltage electrophoresis (12). This communication describes the quick, efficient separation of cysteine-NEM by thin-layer chromatography on silica gel or MN300 cellulose sheets and the usefulness of N-ethylmaleimide-1- 14C and 35S- l-cystine in conjunction with thin-layer chromatography to study the formation of these adducts in metabolic systems.

Fluorometric Analysis of Sodium Fluorescein in Ophthalmic Solutions

Abstract A collaborative study was conducted on a fluorometric method for sodium fluorescein in ophthalmic solutions. Using a standard curve prepared from hydrolyzed fluorescein diacetatc, the dye concentration was determined in a pH 9 buffer (excitation wavelength 460 mµ, emission wavelength 515 mµ). Recoveries for the four solutions were 96–104%. TLC on fluorescent silica gel sheets is used to identify sodium fluorescein, detect possible degradation products, and differentiate acriflavine from hydrochloride. It is recommended that the method be adopted as official first action.

On the identfication of 4-hydroxy-3,5-diiodophenylpyruvic acid in rat thyroid glands.

Recent reports have indicated that 4-hydroxy-3,5-diiodophenylpyruvic acid (dihppa) may be an important intermediate in the biosynthesis of thyroxine. This intermediate has not, however, been identified conclusively in thyroid tissue. Extracts of rat thyroid glands labeled with iodide-125I in vivo were chromatographed on thin-layer silica gel sheets in 2 solvent systems. Radioautographs of these chromatograms showed radioactivity in the dihppa and other areas. Attempts to purify this compound by elution and rechromatography proved unsuccessful. It was shown by ultraviolet spectroscopy that significant structural alterations occurred during these procedures. The resulting compound was tentatively identified as 4-hydroxy-3,5-diiodophenylacetic acid. In other studies, prelabeled rat thyroids were homogenized in hot glacial acetic acid containing 100 mg unlabeled dihppa and 2 mg Nal. The carrier was recrystallized to constant specific activity. After 5 crystallizations the methyl ester of dihppa was synthesize...

Einige betrachtungen bei dem vergleigh verschiedener folienarten

Some observations on the comparison of different types of sheets The various silica gel sheets Chromagram (Eastman), Polygram (Macherey-Nagel), Silufol (Kavalier) as well as Merck and Schleicher & Schüll ready-for-use thin-layer plates, were compared by using them for the separation of water-soluble vitamins. The influence of the origin of the different silica gels, as well as the effect of the binders they contain (calcium sulphate, starch, vinyl compounds, etc.) on the separation under uniform conditions of chamber saturation, was demonstrated. In these experiments the vinyl compounds (polyvinyl alcohol) used as binder had the greatest effect, which was manifested even by reversal of the R F values. The solvent mixture used probably also plays a role in producing this phenomenon, since it was not observed when the same sheet with polyvinyl alcohol as binder was used with another solvent mixture, as was the case in the separation of cholesterol, choloesterol esters and glycerides. For the last-mentioned group of substances, the well-known effect of chamber saturation was also demonstrated. The present experiments show that the optimum conditions for separation of a given mixture must be adapted to the conditions required by the particular sheet.

Séparation des oligonucléotides du DNA apurinique par chromatographie bidimensionnelle sur couches minces de gel de silice

An excellent resolution of the pyrimidine oligonucleotides corresponding to a sample not exceeding 300 to 400 μg of DNA, was achieved by means of two-dimensional thin-layer chromatography on commercially available Kodak silica gel sheets. In each experiment some sixteen nucleotides were identified by using spectrometry and enzymatic methods.