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  • Author or Editor: Charu Sharma x
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The retention behavior of 25 anions on 1:1 silica gel G-starch layers has been studied using two-component non-aqueous mobile phases or aqueous solutions of organic acids and their sodium salts. It was observed that the higher the p K a values of the acids used, the lower the R F values of the anions. Migration depends both on the solubility of the corresponding acid of the anion studied and on adsorption. Quantitative separation of fluoride, molybdate, dichromate, and arsenate ions from other anions has been achieved. The R F values of the anions were found to correlate with their lyotropic numbers.

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The retention behavior of 40 metal ions has been studied on tri-n-butyl phosphate (TBP) and tri-n-butylamine (TBA)-impregnated silica gel G layers in aqueous acid solutions including the complexing acids and butanol‒nitric acid mixtures in varying ratios as mobile phases. The mechanism of migration is explained in terms of solubility of the metal salt, adsorption, complex formation, and precipitation of the ions in the network of the adsorbent. The effect of pk1 of the complexing acids used as the mobile phase and also of the metal complexes formed on the R F values of metal ions is discussed. The effect of the mobile phase composition on the migration behavior of these ions has also been studied. Twenty percent TBPand TBA-impregnated silica gel G layers are found the most suitable for the separation of metal ions. The quantitative separation of lead from other metal ions and synthetic alloys such as architectural bronze and leaded bronze has been carried out.

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Summary

The chromatographic behavior of 24 inorganic anions has been studied on tri-n-butyl amine (TBA) impregnated silica gel-G layers using single solvents, two-component non-aqueous mixtures, and aqueous solutions of organic acids as mobile phases. The mechanism of migration is explained in terms of adsorption, precipitation, solubility of sodium or potassium salts of the anions, and the polarity of the mobile phase used. The effect of pk1 of the complexing acids and that of dielectric constant (∈) of non-aqueous solvents used as mobile phases on the R F values of anions are discussed. Twenty-percent TBA impregnated silica gel-G layers are found quite effective in the separation of anions. The effect of the addition of DMF to other organic solvents on the R F values is also discussed. A number of useful binary and ternary separations are achieved, e.g., the separation of coexisting I, IO3−, and IO4− and of Fe(CN)64 and Fe(CN)63 from their mixtures. The R F values of the anions are found to be in accordance with their lyotropic numbers.

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Penicillins and cephalosporins (subclasses of β-lactam antibiotics) are widely used against Gram-positive and Gram-negative bacteria. Use of HPLC, TLC-bioautography, and thin silica gel layers precoated with fluorescent material has been reported in literature for the analysis of these compounds. This manuscript deals with a straightforward and sensitive method for rapid separation and detection of selected β-lactams. Bulk impregnation of homemade silica gel G layers and impregnation of ready made silica gel 60 layers with 0.2% ammonium chloride was carried out and various mobile phases have been established for UV detection of the compounds. Separation of penicillins (benzylpenicillin, ampicillin, and amoxicillin) and cephalosporins (cephalexin, cefoperazone, ceftriaxone, cefixime, and cefadroxil) was achieved by use of propanol-acetic acid 4:1 ( v/v ) and butanol-acetic acid-water 4:1:2 ( v/v ) respectively, as mobile phases.

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The sorption behavior of a number of metal ions was investigated on thiourea-impregnated silica gel G and alumina layers with aqueous HCl and acetone—HCl mobile phases. The mobility of the metal ions was examined under varying experimental conditions of mobile phase pH, effect of concentration of thiourea as the impregnant, and also the effect of solvent composition in acetone—HCl mixtures. The migration of metal ions depends on the solubility of metal salt, adsorption and precipitation of the ions in the network of the adsorbent. On impregnated silica gel G layers, for many ions, maximum adsorption occurs at pH 2 and above. 0.1 m and 0.2 m thiourea-impregnated alumina layers were found the most suitable for metal ion separations. For some metal ions, comparative study was made with thiourea and urea as the impregnant. Quantitative separations of Pb2+ and Hg2+ from some other metal ions and synthetic alloys were also carried out.

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