Yazar "Erturun, H. Elif Kormali" seçeneğine göre listele

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    A calix[4]arene derivative-doped perchlorate-selective membrane electrodes with/without multi-walled carbon nanotubes
    (SPRINGER HEIDELBERG, 2017) Erturun, H. Elif Kormali; Özel, Ayça Demirel; Ayanoğlu, Melek Nur; Şahin, Özlem; Yılmaz, Mustafa
    In this study, poly (vinyl chloride)(PVC) membrane electrodes with/without multi-walled carbon nanotubes (MWCNTs) based on a calix[4]arene derivative for perchlorate ion were described. The influence of membrane composition, pH, conditioning solution on the potentiometric response of the electrodes was investigated. Perchlorate-selective PVC membrane electrode exhibited a slope of 47.8 +/- 0.6 mV/pClO(4) in the range of 1.0 x 10(-7)-1.0 x 10(-1) mol L-1 at pH 4.0 while the coated Pt electrodes with MWCNT-OH, MWCNT-COOH and MWCNT displayed slopes of 46.1 +/- 0.7 mV/pClO(4) (5.0 x 10(-6)-1.0 x 10(-1) mol L-1), 50.4 +/- 1.9 mV/pClO(4) (1.0 x 10(-6)-1.0 x 10(-1) mol L-1) and 44.4 +/- 0.3 mV/pClO(4) (1.0 x 10(-5)-1.0 x 10(-1) mol L-1), respectively. Other response characteristics of these electrodes such as response time, lifetime and detection limit were identified, and the selectivity coefficients towards various anions were calculated by separate solution method. Moreover, the perchlorate-selective electrodes described here were successfully used as an indicator electrode for the determination of perchlorate in real samples such as tap water, river water and human urine by direct calibration method.
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    Development of a pH sensing membrane electrode based on a new calix[4]arene derivative
    (ELSEVIER SCIENCE BV, 2015) Erturun, H. Elif Kormali; Özel, Ayça Demirel; Sayın, Serkan; Yılmaz, Mustafa; Kılıç, Esma
    A new pH sensing poly(vinyl chloride) (PVC) membrane electrode was developed by using recently synthesized 5,17-bis(4-benzylpiperidine-1-yl)methyl-25.26,27,28-tetrahydroxy calix[4]arene as an ionophore. The effects of membrane composition, inner filling solution and conditioning solution on the potential response of the proposed pH sensing membrane electrode were investigated. An optimum membrane composition of 3% ionophore, 67% o-nitrophenyl octyl ether (o-NPOE) as plasticizer, 30% PVC was found. The electrode exhibited a near-Nernstian slope of 58.7 +/- 1.1 mV pH(-1) in the pH range 1.9-12.7 at 20 +/- 1 degrees C. It showed good selectivity for H+ ions in the presence of some cations and anions and a longer lifetime of at least 12 months when compared with the other PVC membrane pH electrodes reported in the literature. Having a wide working pH range, it was not only applied as a potentiometric indicator electrode in various acid-base titrations, but also successfully employed in different real samples. It has good reproducibility and repeatability with a response time of 6-7 s. Compared to traditional glass pH electrode, it exhibited excellent potentiometric response after being used in fluoride-containing media. (C) 2014 Elsevier B.V. All rights reserved.
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    Salicylate Ion-Selective Electrode Based on a Calix[4]arene as Ionophore
    (WILEY-V C H VERLAG GMBH, 2015) Ayanoğlu, Melek Nur; Erturun, H. Elif Kormali; Özel, Ayça Demirel; Şahin, Özlem; Yılmaz, Mustafa; Kılıç, Esma
    A salicylate-selective electrode based on calix[4]arene derivative was developed and its response characteristics were investigated. The optimum membrane composition was 1% ionophore, 30% PVC, 69% DOS. The electrode exhibited a Nernstian slope of 58.8 +/- 0.5mV/pSal in the range of 1.0x10(-5)-1.0x10(-1)M with a detection limit of 4.3x10(-6)M at pH4.0, 20 +/- 1 degrees C. The potentiometric response of the electrode in the presence of different anions was investigated by the separate solution method. The lifetime was found at least 4months, and its response time was 5-10s. It was successfully used for the potentiometric determination of salicylate in pharmaceutical preparations.