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    Chiral separation of amino acids using a chiral crown ether by impregnation on a polymeric support and monoamine modified silica gel
    (Pergamon-Elsevier Science Ltd, 2006) Seyhan, Serap; Turgut, Yilmaz; Merdivan, Melek; Hosgoren, Halil
    A chiral monoaza-15-crown-5 ether derivative was prepared from L-Leucinol and used as a chiral stationary phase. The new chiral stationary phases CSP-1 and CSP-2 were employed in separating the enantiomers of the sodium and potassium salts of amino acids. The sodium and potassium salt of the D-enantiomers of all amino acids (PhyAlaNa, PhyAlaK and PhyGlyNa, PhyGlyK, and TrpNa, TrpK) show higher selectivity than the L-enantiomers for both CSP-1 and CSP-2. (c) 2006 Elsevier Ltd. All rights reserved.
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    Öğe
    Polymer supported 5,10,15,20-tetrakis(phenoxy acetic acid)porphyrin derivative for separation and preconcentration of d- and f-electron metals
    (Springer Wien, 2008) Seyhan, Serap; Merdivan, Melek; Demirel, Nadir; Hosgoren, Halil
    5,10,15,20-tetrakis(phenoxy acetic acid) porphyrin (PAAP) was covalently linked to Merrifield chloromethylated resin. Characterization of PAAP and the modified polymeric matrix were performed by H-1 NMR, FTIR and elemental analysis. The sorbent was used for the separation and enrichment of the d-electron metals (Mn(II), Co(II), Ni(II), Cu(II) and Zn(II)) at pH 6-8 and of the f-electron metals U(VI) and Th(IV) at pH 4-5. The metals ions were preconcentrated with a concentration factor range of 115-215 and then determined by flame atomic absorption spectrometry or visible spectrophotometry using Arsenazo(III). The retained metals were eluted with 2.0 mol L-1 HNO3 in the case of the d-electron metals and 0.1/0.25mol L-1 HCl in the case of the f-electron metals. The procedure was validated by analyzing the NIST standard reference material 2709 (San Joaquin Soil).
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    Öğe
    Solid phase extractive preconcentration of trace metals using p-tert-butylcalix[4]arene-1,2-crown-4-anchored chloromethylated polymeric resin beads
    (Elsevier, 2007) Seyhan, Serap; Colak, Mehmet; Merdivan, Melek; Demirel, Nadir
    5,11,17,23-Tetrakis(1,1-dimethylethyl)-25,26-dihydroxy-27,28-crown-4-calix[4]arene in the cone conformation was synthesized. This p-tertbutylcalix[4]arene-1,2-crown-4 compound was then anchored with Merrifield chloromethylated resin beads. The modified polymeric resin was characterized by H-1 NMR, FT-IR and elemental analysis and used successfully for the separation and preconcentration of Cu(II), Cd(II), Co(II), Ni(II) and Zn(II) prior to their determination by FAAS. Effective extraction conditions were optimized in both batch and column methods. The resin exhibits good separating ability with maximum between pH 6.0-7.0 for Cu(II), pH 6.0 for Cd(II), pH 5.0 for Co(II), pH 4.0-4.5 for Ni(II), and pH 4.5 for Zn(H). The elution studies were carried out with 0.5 mol L-1 HCL for Cu(II), Co(II) and Co(II), 1.0 mol L-1 HCl for Cd(II) and Zn(II). The sorption capacity, preconcentration factor and distribution coefficient of each metal ion were determined. The detection limits were 1.10, 1.25, 1.83, 1.68 and 2.01 mu g L-1 for Cu(II), Cd(II), Co(II), Ni(II) and Zn(II). The influence of several ions on the resin performance was also investigated. The validity of the proposed method was checked for these metal ions in NIST standard reference material 2709 (San Joaquin Soil) and 2711 (Montana Soil). (c) 2006 Elsevier B.V. All rights reserved.
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    Öğe
    Use of o-phenylene dioxydiacetic acid impregnated in Amberlite XAD resin for separation and preconcentration of uranium(VI) and thorium(IV)
    (Elsevier Science Bv, 2008) Seyhan, Serap; Merdivan, Melek; Demirel, Nadir
    The impregnation of o-phenylene dioxydiacetic acid (OPDA) into a polymeric matrix, Amberlite XAD-2000, is reported and was characterized by infrared spectroscopy. The amount of attached OPDA to the polymer resin was found to be 1.77 mmol g(-1) resin. The resin was used for the sorption of U(VI) and Th(IV) from aqueous solution. This sorbent was capable of preconcentrating U(VI) and Th(IV) from weakly acidic or neutral solution. The retained metals were eluted sequentially using 0.25 mol L-1 HCl for U(VI) and I mol L-1 HCl for Th(IV) and determined spectrophotometrically using arsenazo-(III). The capacity of the resin for U(VI) and Th(IV) was found to be 0.121 and 0.113 mmol g(-1), respectively. The impregnated resin exhibits a high chemical stability, reusability and fast equilibration. The method was used for the determination of U(VI) and Th(IV) in synthetic samples and rock samples. (C) 2007 Elsevier B.V. All rights reserved.