Thin Layer Chromatography of Synthetic Dyes on Antimonic Acid and on Admixture of Antimonic Acid and Silica Gel ‘G’ in a Mixed Solvent System

Abstract

Thin layer chromatography of synthetic dyes have been performed on antimonic acid and on admixture of antimonic acid and silica gel ‘G’ in a mixed solvent system i. e. Butanol: Acetic acid: water (25:5:10). The separation potential of antimonic acid and silica gel ‘G’ has been explored. Several important separations of closely related dyes have been achieved as a result of such studies.     

Incorporation of Triarylmethane Dyes into Sol–Gel Matrices Deposited on Textiles

The incorporation of triarylmethane dyes into sol–gel layers formed by modified silica was used for coating of textile materials. The coatings were performed with three triarylmethane dyes differ in electrical net charge and structure: The cationic dye Malachite Green, the anionic Guinea Green and the non-polar Reflex Blue 61. All coating procedures were performed using an acidic sol–gel process starting from a solution of tetraethoxysilane (TEOS) and the dye in a mixture of water and ethanol. Depositions were performed on polyester, polyamide and cotton textiles. Investigation of leaching and photobleaching fastness showed that the stability of the dyes was enhanced by incorporation into the silica layer. Sufficient leaching fastness was only achieved with the cationic dye due to direct attractive electrostatic interaction with the negatively charged silica matrix. Also the addition of a small amount of epoxysilane to the silica sols lead to an enhancement of leaching and bleaching fastness.     

The Chromatographic Behavior of some Hydrophilic Dyes and Dye Intermediates on Thin Layers of Strong and Weak Ion Exchangers

Abstract

The chromatographic behavior of some polar organic dyes and dye intermediates on thin layers of various forms of cationic and anionic exchange resins has been investigated. The results of this study indicate that the stationary ion and the mobile ion of both types of exchangers greatly affect both the level of tailing and the R_f values of the adsorbed compounds. It is also clear from this study that these resins are more suitable for evaluating the relatively simple dyes containing an SO₃Na group than the higher molecular weight polyazo direct dyes used on cellulosic substrates, and that the Li⁺ and H⁺ forms of the cation exchangers work better than their counterparts. On the other hand, cationic dye molecules require the use of anion exchangers, with the ^?OAc form giving better chromatograms than the C104^? form.     

TLC Separations of Amino Acids on Silica Gel Impregnated Layers

Abstract

Copper sulphate and polyamide were tried as impregnants for improving the separation of twenty amino acids on silica gel ‘G’ layers using a new solvent system MeOH-BuOAc-AcOH-Pyridine(20:20:10:5). Tables are presented to illustrate the improvement in resolution of amino acids on silica gel plates.     

Reverse Phase Thin-Layer Chromato-Graphy of some Metal Ions on Butyl-Amine Impregnated Silica Gel G in Formic Acid Medium

Abstract

Reversed phase thin layer chromatography of metal ions have been performed on s-butylamine and t-butylamine impregnated silica gel thin layers in formic acid and sodium formate systems. Separation potential of impregnated silica gel thin layers was explored. Impregnated silica gel layers were found to be more selective (strongly sorbing) than unimpregnated silica gel chromo-toplates. Several important binary and ternary separations were achieved on impregnated thin layers.     

Chelation Ion Chromatography on DMSO Impregnated Silica Gel-G Layers: Specific Separation of Cd2+, W6+, and Zr4+ from Transitional Metal Ions

Abstract

Chelation ion chromatography of metal ions on DMSO impregnated silica gel-G layers in ether; DMSO: 1M HNO₃ (1:1); n-butanol: acetone: HNO₃ (6:6:1) and di-isopropyl ether: DMSO: THF systems having varying compositions, was performed. The zero R_f for a number of cations is explained in terms of precipitation and strong adsorption. It was possible to separate Cd²⁺, W⁶⁺, Zr⁴⁺, Zn²⁺ and VO²⁺ from numerous metal ions. A number of analytically important binary and ternary separations were also achieved and were found useful in synthetic alloy analysis.     

Thin Layer Chromatography of Metal Ions Complexed with Anils Part - VI

Abstract

Thin layer chromatographic detection, separation and determination of Ti(IV), UO₂(II), Au(III) and Hg(II) complexes with λ - and β - naphthylanils of methylenediglyoxal have been made on silica gel layers. No locating agent was used as the complex spots were self evident in day light.     

Formation of Water-Soluble Dye-Doped Silica Particles

Formation mechanism of dye-doped silica particles less than 1 µm in diameters by the Stöber method was investigated. With increasing the content of dyes such as water-soluble porphyrin (TTMAPP) and laser dye (Nile blue), these dye-doped silica particles showed the similar tendency to the following characters: (1) Particle size increased, passed through the maximum at the dye content corresponds to the isoelectric point, and then followed by decrease; (2) Ratio of dimer and monomer of the incorporated dye decreased. In aqueous solution positively charged dyes showed good affinity with negatively charged SiO₂ primary particles from the early stage of the formation. Zeta potential of doped-silica particles was measured against nominal dye content: from non-doped to highly doped particles, their surface charge changed from negative to positive. The similar influence caused by positively charged dyes on the particle formation was also observed by Ca²⁺ doping.     

A Comparison of Amino Acid Separations on Silica Gel,Cellulose, and Ion Exchange Thin Layers

Abstract

Separations of amino acids on silica gel, high performance silica gel, preadsorbent silica gel, microcrystalline and fibrous cellulose, and Fixion strong acid cation exchange layers were compared under standardized conditions using a mixture of the nine essential acids and a more complex 18-component mixture. Fixion layers were evaluated using three different development conditions, and loading studies of raw urine were carried out on all of the layers. Tables and figures are presented illustrating which amino acids can be resolved in each of the chromatographic systems.     

Beitr?ge zur Papierchromatographie organischer Substanzen

Zusammenfassung Ungesättigte Verbindungen, hauptsächlich Olefine C₂–C₁₂, werden als Quecksilber(II)-salze mit Hilfe der Papierchromatographie und Dünnschichtchromatographie aufgetrennt. Geeignete Lösungsmittelgemische werden angegeben und die Zusammenhänge mit Fleckengröße und R_f-Werten graphisch dargestellt.

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Summary Unsaturated compounds, mainly olefines C₂–C₁₂, are separated in form of their mercuric salts by help of chromatography on paper or on thin layers of silica gel. Suitable solvent mixtures are given and their relations to spot sizes and R_f-values are represented in graphs.

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IV. Mitteilung: Kabil, A., u. V. Prey: Mh. Chem. 89, 497 (1958).     

Crown-containing butadienyl dyes 8. Structures and complexation of chromogenic dithia-15(18)-crown-5(6) ethers

The structures of new butadienyl dyes of the benzothiazole series containing the dithia-15-crown-5 (2a) or dithia-18-crown-6 (2b) fragments were established by X-ray diffraction. Complexation of dyes 2a,b with Hg²⁺, Pb²⁺, Cd²⁺, Ag⁺, Zn²⁺, and alkaline-earth cations in aqueous-acetonitrile solutions was studied by spectrophotometry. At a high percentage of water in solutions (P _w ≈ 50%), these dyes have a very low ability to bind Pb²⁺ cations (logK < 2) and virtually do not bind Cd²⁺, Zn²⁺, and alkaline-earth cations. At the same time, these dyes form stable 1: 1 complexes with Hg²⁺ and Ag⁺ cations at all P _w. The stability constants of complexes with the Ag⁺ cation increase with increasing P _w because the free energy of hydration of this cation is much lower than the free energy of solvation in acetonitrile. In the P _w range from 0 to 75%, the stability constants of the complexes of dyes 2a,b with the Hg²⁺ cation are larger than those of the corresponding complexes with the Ag⁺ cation by more than four orders of magnitude. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 90–96, January, 2006.     

Determination of Triazine and Chlorophenoxy Acid Herbicides in Natural Water Samples By Solid Phase Extraction and Quantitative Thin Layer Chromatography

Abstract

Atrazine, simazine, 2, 4-D, silvex, and 2, 4, 5-T, were determined in natural water samples at 10 ppb levels by solid phase extraction on disposable C₁₈ columns and TLC on preadsorbent silica gel layers impregnated with AgNO₃, exposure to UV light, and densitometric scanning. Recoveries ranged from 70 to 88% for the triazines and 93 to 100% for chlorphenoxy acid herbicides, with average CV values of 7 to 8%. Solid phase extraction proved to be an advantageous alternative to classical liquid-liquid partition for the analysis of water for these compounds by quantitative TLC.     

Extraction of dyes contained in glow sticks using liquid CO2

ABSTRACT

Separation of glow stick dyes adhered to a cotton swab using liquid CO₂ provides an engaging demonstration of several chemical concepts including polarity, kinetics, chemiluminescence, and the importance of CO₂ a green solvent. The simple protocol allows access to a broad range of students. Differential polarities of the glow stick dyes allow certain dyes to be preferentially dissolved in liquid CO₂, leaving other dyes adhered onto cotton. Both TCPO (bis(2,4,6-trichlorophenyl)oxalate) and H₂O₂, which together provide the necessary reaction for chemiluminescence, are present in both the extracted liquid and cotton upon dissipation of CO₂. Thus, it is possible to compare the emission spectrum of the extracted fluid to that of the original glow stick and the residue left on the cotton swab. Emission peaks resulting from the presence of polar dyes in the original glow stick and on the cotton are routinely observed to be missing in the extracts.     

A novel self-assembly based on double-layer zinc porphyrin sensitizers in supramolecular solar cell

Two new self-assemblies based on zinc porphyrin dyes ZnPx-ZnPA (x?=?1, 2) were synthesized and used for dye-sensitized solar cells. Capping layer dyes consist of zinc porphyrin (ZnP) as core unit and carbazole (P1), phenothiazine (P2) as electron-donating group. The dye ZnPA contains carboxylic group as an anchor porphyrin with upper dyes (denoted as ZnP1 and ZnP2) formed dyads by coordination bonds of Zn-to-ligand self-assembled devices. The assembly modes were also verified by transmission electron microscopy (TEM). The influence of the upper porphyrins on molecular structure as well as photovoltaic performance was investigated via photophysical and electrochemical studies and calculations. With addition of the phenothiazine unit, the ZnP2-ZnPA possesses better light-harvesting capability with a significantly red-shifted Q-band. The photoelectrochemical efficiencies for ZnP2-ZnPA are better than those of ZnP1-ZnPA ascribed to larger J_sc and V_oc.

     

Effect of High-Temperature Treatment on Optical Properties of Silica Films Doped with Al2O3, P2O5 and Rare-Earth Elements

The paper reports effects of high-temperature treatment of silica layers doped with Al₂O₃, P₂O₅, Yb and Er ions, which are coated inside silica substrate tubes and transformed through viscous flow into the core of a preform, on properties of these cores. The gel layers are applied inside the silica substrate tubes from sols based on tetraethoxysilane and corresponding chlorides in isopropanol by controlled lowering the column of the sol. The layers are thermally treated at 500°C and subject to high-temperature treatment from 1000 to 1300°C. The tube with the layers is collapsed into a preform from which fibers are drawn at about 1950°C. The results of concentration measurements show that during the high-temperature treatment the content of silica in the layer increases at least five times in comparison with that of the sol composition. This effect depends on the sol composition and the number of the coated gel layers. Measurements show that in the prepared fibers there is some remaining unsaturated absorption of erbium ions at 1535 nm, which is related to quenching of the erbium ions.     

New Inexpensive and Selective Sorbent Phases for Rapid Thin Layer Chromatographic Analysis of Metal Ions

Abstract

New sorbent phases have been developed by impregnating silica gel G with different inorganic salts for the analysis of metal ions by thin layer chroma to graphy in carboxylic acids media. Thin layers prepared from silica gel G impregnated with ammonium chloride or barium nitrate show the unusual selectivity towards metal ions in comparison to the thin layers prepared from plain silica gel G or silica gel impregnated with silver nitrate or aluminium nitrate. Many qualitative separations     

Chromatography of Anions on Alumina Thin Layers: Effect of Transition Metals on CI−-Br−-I− and No− 2-NO− 3 Separations

Abstract

Chromatographic behaviour of eighteen anions on thin layers of alumina and alumina mixed with silica gel (1:1, 1:2 and 2:1) has been studied using mixed acidic organic solvent systems containing formic acid. Though the addition of silica gel to alumina enhances the mobility and clarity of detection of anions, but it causes the increased tailing for Fe(CN)^3- ₆, Cr0₄ ^2- and Cr₂O₄ ^2-. Formic acid is responsible for the differential migration of anions. All the anions remained at the starting line (R_F = 0) in pure organic solvents. Formic acid-Ketone systems gave better results compared to formic acid-alcohol systems. Development time increases with the increase of viscosity/mol. wt. of organic solvents. The mutual separation of C1, Br^?, Br^?, I^? and NO^? ₂ and NO^? ₃ were achieved on pure alumina using formic acid-acetone solvent systems. The effect of transition metals (Ti, V, Cr, Mn, Fe, Co, Ni, Cu and Zn) on C1^?-Br^?-I^? and NO^? ₂-NO^? ₃ separations has been studied.     

A new decavanadate polyoxovanadate nanocluster: synthesis,characterization and rapid adsorption of methylene blue

A new decavanadate polyoxovanadate nanocluster, [2-ampH]₆[V₁₀O₂₈]?2H₂O (1), was synthesized through reaction between ammonium vanadate and 2-aminopyridine at pH = 2. Nanocluster 1 was characterized by IR, elemental analysis, and X-ray crystallography. 1 was found to adsorb and desorb dyes and may have widespread application in wastewater treatment. The utility of 1 for adsorption of methylene blue was studied. The adsorbed dyes can be easily desorbed, and 1 has full efficiency after five cycles.     

IR spectroscopic study of the basicity of aminated silica gels

The aminated silica gels SiO₂/SOCl₂/NH₃ (I), SiO₂/SiCl₄/NH₃ (II), SiO₂/BCl₃/NH₃ (III), and SiO₂/γ-aminopropyltriethoxysilane (SiO₂/APTES, IV) have been synthesized. According to DRIFT spectroscopy and chemical analysis data, the surface amino groups of I–III are “free,” while those of IV interact with the surface OH groups of the silica gel and with one another. The strength of basic sites has been measured on the proton affinity (PA) scale as the shift of the ν(CD) band of adsorbed deuterochloroform. The basicity of an aminated silica gel depends on its chemical composition. Silica gel IV (PA = 938 kJ/mol) is a stronger base than I–III (PA = 829 kJ/mol). As the basicity of the NH₂ group decreases, the N-H stretching band shifts to higher frequencies.     

Preconcentration of Uranium in Seawater with Heterocyclic Azo Dyes Supported on Silica Gel

Abstract

The chelating adsorbents, heterocyclic azo dyes supported on silica gel, were prepared and their adsorption behaviors of metal ions were investigated. The 1-(2-pyridylazo)-2-naphthol(PAN)-SG and 2-(2-thiazolylazo)-p-cresol(TAC)-SG show greater affinity for UO₂(II) and ZrO(II), compared with the other metal ions like Cu, Cd, Fe and alkaline earths. Trace uranyl can be quantitatively retained on the column of the gels at neutral pH region and flow-rate 3–4 ml/min. The uranyl retained is easily eluted from the column bed with a mixture of acetone and nitric acid(9:1 v/v) and determined by spectrophotometry using Arsenazo-III. Matrix components in seawater do not interfere and the spiked recovery of uranyl in artificial seawater was found to be average 98.6 %, with the relative standard deviation of 1.08 %. Both gels were applied to the determination of uranium in seawater with satisfactory results.