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Öğe 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, MustafaIn 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.Öğe 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, EsmaA 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.Öğe A hydrogen ion-selective poly(vinyl chloride) membrane electrode based on calix[4]arene as a perchlorate ion-selective electrode(SCIENTIFIC TECHNICAL RESEARCH COUNCIL TURKEY-TUBITAK, 2008) Canel, Esin; Erden, Sevcan; Özel, Ayça Demirel; Memon, Sahahabuddin; Yılmaz, Mustafa; Kılıç, EsmaA hydrogen ion-selective electrode was prepared using 5,11,17,23-tetra-tert-butyl-25,26,27,28-tetracyanometoxycalix[4]arene and the possibility of its use as a perchlorate ion-selective electrode was investigated using its characteristic of becoming perchlorate sensitive in acidic regions. The electrode of the optimum characteristic had a composition of 1% ionophore, 66% o-NPOE, and 33% PVC. This electrode exhibited a linear response over the range 1.0 x 10(-1)-1.0 x 10(-5) M of perchlorate with a slope of 48.7 +/- 0.5 mV per p[ClO4]. The effects of the pH and the membrane composition were also investigated. The lifetime of the electrode was at least 4 months and its response time was 10(-15) s. The selectivity coefficients of some anions were calculated by the matched potential method.Öğe İyonofor olarak bir kaliks[4]aren türevinin kullanıldığı iyodür-seçici PVC membran elektrot(2017) Göver, Tuğçe; Ertürün, H. Elif Kormalı; Özel, Ayça Demirel; Erdemir, Serkan; Canel, EsinBu çalışmada, iyonofor olarak 5,11,17,23-tetra(tert-bütil)-25,26,27,28- tetra(4-propilimidazol asetamit)-kaliks[4]aren bileşiğinin kullanıldığı iyodürseçici yeni bir polivinil klorür (PVC) membran elektrot hazırlandı. İyodür –seçici membranın hazırlanmasında kullanılan PVC, o-nitrofeniloktileter (o-NPOE; plastikleştirici) ve iyonoforun oranı değiştirilerek, optimum membran bileşimi %2 iyonofor, %29,7 PVC, %68,3 o-NPOE olarak bulundu. pH 4,0'de elektrodun doğrusal çalışma aralığının ve eğiminin sırasıyla 1,010-5 – 1,010-2 M ve 52,1 2,6 mV/pI olduğu belirlendi. Önerilen elektrodun oldukça kısa bir cevap süresine (5- 10 s) ve 5 ay’dan daha uzun bir ömre sahip olduğu gözlendi. Elektrot diğer anyonlar varlığında ISalisilat ClO4- NO3- SCN- Benzoat NO2- Br- Cl- F Sitrat HCOO- sırasında bir seçicilik gösterdi. Ayrıca, önerilen elektrot, gümüş nitrat ile iyodürün çöktürme titrasyonunda indikatör elektrot olarak başarılı bir şekilde kullanıldı.Öğe NEW SILVER ION-SELECTIVE PVC MEMBRANE AND COATED-GRAPHITE ELECTRODES BASED ON A NOVEL CALIX[4]ARENE DERIVATIVE(WALTER DE GRUYTER GMBH, 2009) Erol, Sibel; Özel, Ayça Demirel; Yılmaz, Mustafa; Kılıç, EsmaA new PVC membrane and a coated graphite electrode (CGE) based on a recently synthesized calix[4]arene compound of 5,11,17,23-tetra-tert-butyl-25,27-metoxy-26,28-bis(potassiumksantato)etoxycalix[4]arene as a suitable carrier for silver (I) ion are described. The electrodes exhibit a Nernstian slope of 57.7 +/- 1.3 mV/p[Ag] for PVC membrane electrode and 54.7 +/- 2.1 mV/p[Ag] for CGE over a wide concentration range from 1.0 10(-2) to 1.0x10(-6) M and 1.0x10(-2) to 1.0x10(-5) M, respectively. They have a fast response time (similar to 10 s) and can be used for at least 60 days for PVC membrane electrode and 30 days for CGE without any considerable divergence in potentials. The proposed electrodes show high selectivity towards silver (I) ions with respect to alkali, alkaline earth and several transition and heavy metal ions. Only interference of Hg2+ is found. The potentiometric responses are independent of the pH of test solution in the pH range of 2.0-6.0. Application of only PVC membrane electrode as an indicator electrode in potentiometric titrations of chloride, bromide and iodide ions was reported.Öğe 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, EsmaA 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.
