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Cetylpyridinium chloride micelle-mediated mutual separation of zinc, cadmium, and mercury ions by thin-layer chromatography

Mohammad A., Agrawal V., Shahab H.

Acta Chromatographica

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2007

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No. 19

185-196

EN

Cationic surfactant-mediated systems containing different concentrations of cetylpyridinium chloride have been used as mobile phases in thin-layer chromatographic separation of metal cations on silica layers. The effect of surfactant concentrations below and above the critical micelle concentration (CMC) on the retention behaviour of metal ions was examined. The best TLC system for rapid mutual separation of Zn2+, Cd2+, and Hg2+ was unmodified silica as stationary phase and 5% aqueous cetylpyridinium chloride as mobile phase. The effects of pH (acidity or basicity), inorganic electrolytes (the acetate, formate, chloride, bromide, and carbonate of sodium and the chloride and nitrate of calcium), and organic compounds (urea) in the cetylpyridinium chloride solution on the mobility and separation efficiency of Zn2+, Cd2+, and Hg2+ were assessed. The limits of detection for these metal cations were also determined. The method is well suited to identification and separation of Hg2+, Zn2+, and Cd2+ from synthetically prepared ores, for example cinnabar (HgS), zinc blende (ZnS), and greenoekite (CdS), and from hydroxide sludge.

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Use of a glutamic acid-containing aqueous-organic mobile phase for on-plate separation, detection, and identification of cationic and non-ionic surfactants by thin-layer chromatography

Mohammad A., Shahab H.

Acta Chromatographica

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2006

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No. 17

272-291

EN

A new thin-layer chromatographic system comprising silica gel G as stationary-phase and a three-component mobile phase, 0.1 M glutamic acid–methanol–acetone, 1:1:1 (v/v), has been found to be highly suitable for separation and identification of cationic and non-ionic surfactants. The experimental conditions were optimized to achieve differential migration of the surfactants. In addition to achieving separation of some important cationic and non-ionic surfactants on laboratory-prepared silica gel layers and on silica gel HPTLC plates, tetradecyltrimethylammonium bromide (TTAB) has been successfully separated from Triton X-100 (TX-100) in the presence of heavy metal cations. The method has been used for identification of TTAB and TX-100 in saline water, river water, and domestic waste water. Limits of detection were determined for TTAB and TX-100. TLC coupled with spectrophotometry was used for quantitative estimation of TTAB after preliminary separation from TX-100. The effects on separation of TTAB from TX-100 of sample pH, polarity of the alcohol in the mobile phase, nature of the amino acid in the mobile phase, and the presence of alumina, kieselguhr, or cellulose in the silica layer have also been examined.

3

Use of micellar anionic surfactant solutions with added carbohydrates as mobile phases in thin-layer chromatography of heavy metal cations. Separation of mixtures of aluminium(III), manganese(II), and chromium(VI)

Mohammad A., Shahab H.

Acta Chromatographica

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2005

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No. 15

192-205

EN

A new thin-layer chromatographic system comprising silica gel "G" as stationary phase and a micellar solution of sodium dodecyl sulphate (0.01 M) with added maltose (0.5 M) in 7:3 (v/v) ratio has been identified as most favourable for identification and separation of mixtures of alumi-nium(III), manganese(II), and chromium(VI). The presence of the carbo-hydrate enhances the separation efficiency of micellar solution of anionic surfactant (i.e. SDS). The experimental conditions were optimized to achieve separation of aluminium, manganese, and hexavalent chromium under dif-ferent experimental conditions of sample pH, layer material composition, presence of foreign substances in the sample, nature of the polar head group of the surfactant, and the nature of the carbohydrate in the micellar mobile phase. The limits of detection and semiquantitative determination of the separated metal cations were also determined.