- Turkey
Ömer IŞILDAK
Gaziosmanpasa University, Chemistry, Faculty Member
BackgroundIonophores in the composition of potentiometric ion‐selective electrodes interact directly with the analyte ion and enable the determination of ionic species in various samples.ObjectivesIn this study, a novel ion‐selective... more
BackgroundIonophores in the composition of potentiometric ion‐selective electrodes interact directly with the analyte ion and enable the determination of ionic species in various samples.ObjectivesIn this study, a novel ion‐selective electrode based on 5‐bromosalicylaldehyde thiosemicarbazone was developed for the selective determination of Cr3+ ions.MethodsThe optimum electrode composition contained ionophore, poly (vinyl chloride) (PVC), bis (2‐ethylhexyl) sebacate (BEHS) and potassium tetrakis (p‐chlorophenyl) borate (KTpClPB) in ratios of 4.0: 61.0: 34.0: 1.0 (mg), respectively. Potential measurements were performed using a computer‐controlled multi‐channel potentiometric measurement system.ResultsThe developed Cr (III)‐selective electrode exhibited a low detection limit of 3.96 × 10−6 M over a wide concentration range of 1.0 × 10−5 – 1.0 × 10−1 M (R2: 0.9979). The electrode exhibited good selectivity towards Cr3+ ions among metal ions with different charges. The chromium (III)‐selective electrode, which exhibited highly reproducible results in three different concentration ranges, also had a very fast response time of 5 s.ConclusionsThe developed Cr (III)‐selective electrode were successfully performed in various beverage samples. As a result, the proposed electrode can be an alternative to other analytical methods in the analysis of Cr3+ ions.
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Ion-selective electrodes or sensors are preferred by researchers in the determination of various ions since they provide very high selectivity and wide concentration range in environmental, industr...
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A poly(vinyl chloride) (PVC) membrane potentiometric sensor was developed for the determination of anti‐epileptic drug levetiracetam. For this purpose, levetiracetam‐tetraphenylborate (LEV‐TPB) ion‐pair was synthesized and the synthesized... more
A poly(vinyl chloride) (PVC) membrane potentiometric sensor was developed for the determination of anti‐epileptic drug levetiracetam. For this purpose, levetiracetam‐tetraphenylborate (LEV‐TPB) ion‐pair was synthesized and the synthesized ion‐pair was used as ionophore in PVC membrane structures. The membrane composed of 3.0 % (w/w) LEV‐TPB ion‐pair, 32.0 % (w/w) PVC, and 65.0 % (w/w) o‐nitrophenyloctylether (o‐NPOE) was determined as the membrane with the best potentiometric properties. The developed sensor exhibited a linear response in the concentration range from 1.0×10−5 to 1.0×10−1 mol L−1 and had a detection limit of 6.31×10−6 mol L−1. For this sensor, pH working range and response time were determined as 6.0–8.0 and ≈25 s, respectively. The sensor displayed a good selectivity for levetiracetam in the presence of a number of common ionic species and some anti‐epileptic drug. The proposed levetiracetam‐selective sensor was successfully applied for the determination of levetiracetam in pharmaceutical drug samples which is used in the treatment of epilepsy.
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Research Interests: Medicine and Gynecology
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In this study, a novel PVC‐based membrane containing (E)‐2‐(1‐(4‐(3‐(4‐chlorophenyl)ureido)phenyl)ethylidene)hydrazine carbothioamide (5) as an electroactive component (ionophore) along with potassium tetrakis (p‐chlorophenyl) borate... more
In this study, a novel PVC‐based membrane containing (E)‐2‐(1‐(4‐(3‐(4‐chlorophenyl)ureido)phenyl)ethylidene)hydrazine carbothioamide (5) as an electroactive component (ionophore) along with potassium tetrakis (p‐chlorophenyl) borate (KTpClPB) and bis(2‐ethylhexyl)adipate (DEHA) in the ratio 4.0 : 32.0 : 1.0 : 63.0 (ionophore:PVC:KTpClPB:DEHA) (w/w) was used to develop a lead(II)‐selective potentiometric sensor. The sensor exhibited a Nernstian response over a wide concentration range from 1.0×10−5 to 1.0×10−1 mol L−1 with a slope of 28.0±2.0 mV/decade, and a detection limit of 1.65×10−6 mol L−1. It displayed very good selectivity towards Pb(II) ions over other cationic species. The lead(II)‐selective sensor showed a fast response time of 5 s, good repeatability, and it worked in the broad pH range of 5.0–11.0. The sensor could be used as an indicator electrode in the quantification of Pb(II) by potentiometric titration against ethylenediaminetetraacetic acid (EDTA). In addition, this sensor was applied for the direct determination of Pb(II) in different water samples including spring water, purification water, commercial water, waste water and in a waste battery sample.
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Porphyrins are a group of macrocyclic compounds which are widely used in many applications in the literature due to their multiple functions. One of their application areas is in the development of sensors which transform changes in... more
Porphyrins are a group of macrocyclic compounds which are widely used in many applications in the literature due to their multiple functions. One of their application areas is in the development of sensors which transform changes in physical and chemical parameters into electrical signals. Novel chemical sensors selective and sensitive for many anions and cations have been fabricated with the advancements in the technology. Real sample applications of these sensors can be successfully performed. In recent years, potentiometric methods have drawn researchers' attention and they have been highly studied because of their superiority over other analytical devices. Ionophores which are used in the development of potentiometric sensors and ion-selective electrodes are the most important components of these systems. Therefore, porphyrin molecules, which have favorable chemical structures, can be directly used as an active component (ionophore) in the structure of potentiometric sensors. In this review, we investigated porphyrin derivatives used as ionophore in the design of potentiometric sensors and we focused on newly developed potentiometric sensors based on porphyrin.
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Research Interests: Engineering, Thermodynamics, Chemistry, Scanning Electron Microscopy, Medicine, and 12 moreAdsorption, Hazardous Materials, Sorption, Bentonite, Specific surface area, Fourier transform infrared spectroscopy, Stearic Acid, Rice husk Ash, Thermodynamic Parameter, Molecular Structure, Freundlich Isotherm, and silanes
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... 11. Buck, CF, Mayewski, PA, Spencer, MJ, Whitlow, S., Twickler, MS, and Barrett, D., J. Chromatogr. A, 1992, vol. 594, p. 225. 12. Isildak, I. and Covington, AK, Electroanal., 1993, vol. 5, p. 815. 13. Hong, US, Kwon, HK, Nam, H.,... more
... 11. Buck, CF, Mayewski, PA, Spencer, MJ, Whitlow, S., Twickler, MS, and Barrett, D., J. Chromatogr. A, 1992, vol. 594, p. 225. 12. Isildak, I. and Covington, AK, Electroanal., 1993, vol. 5, p. 815. 13. Hong, US, Kwon, HK, Nam, H., Cha, GS, Kwon, KH, and Peang, KJ, Anal. Chim. ...
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A novel poly(vinyl chloride; PVC) membrane‐based Cu(II)–selective sensor has been developed using synthesized 5,10,15,20‐tetrakis(4‐methoxycarbonylphenyl)porphyrin as an ionophore. The Cu(II)–selective sensor exhibits a Nernstian response... more
A novel poly(vinyl chloride; PVC) membrane‐based Cu(II)–selective sensor has been developed using synthesized 5,10,15,20‐tetrakis(4‐methoxycarbonylphenyl)porphyrin as an ionophore. The Cu(II)–selective sensor exhibits a Nernstian response for Cu(II) ion over a wide concentration range of 1.0 × 10−5 to 1.0 × 10−1 mol L−1 with the slope of 27.0 ± 2.5 mV/decade, and a lower limit of detection of 1.88 × 10−6 mol L−1. The novel sensor shows good repeatability and high selectivity for Cu(II) ions over other mono‐, bi‐ and trivalent cations. The sensor potential response remains unaffected by pH in the range of 4.4–10.6 and exhibits a fast response time of less than 10s. Finally the developed Cu(II)–selective sensor has been successfully used as an indicator electrode in the potentiometric titration of Cu2+ against ethylenediaminetetraacetic acid and also in the determination of Cu(II) ion concentration in different water and beverage samples.
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In this study, a simple and highly selective potentiometric sensor has been developed for the determination of cobalt(II) ions based on a poly(vinly chloride) (PVC) membrane. As an ionophore, a hydrazone derivative molecule (3) was... more
In this study, a simple and highly selective potentiometric sensor has been developed for the determination of cobalt(II) ions based on a poly(vinly chloride) (PVC) membrane. As an ionophore, a hydrazone derivative molecule (3) was synthesized for the first time, and its characterization was completed using NMR, FT‐IR and Q‐TOF spectroscopic techniques. The developed sensor works well in the linear concentration range of 1.0×10−6–1.0×10−1 Μ with Nernstian slope of 28.6±1.7 mV/decade of activity. The developed cobalt(II)–selective sensor has a low detection limit of 3.09×10−7 Μ, and a very fast response time of 5 seconds. The sensor, which exhibits a highly selective behaviour towards cobalt(II) ions compared to other metal cations, works in the pH range of 6.0–10.0 without being affected by changes in pH. The developed sensor could be used as an indicator electrode in potentiometric titration of Co(II) ions with EDTA. Finally, the developed cobalt(II)‐selective sensor was successful...
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A novel potentiometric sensor based on ionophore (2-Hydroxymethyl-15-crown-5) for the determination of Fe3+ ions is developed. The Fe3+-selective membrane sensor demonstrates high sensitivity and short response time. The detection limit... more
A novel potentiometric sensor based on ionophore (2-Hydroxymethyl-15-crown-5) for the determination of Fe3+ ions is developed. The Fe3+-selective membrane sensor demonstrates high sensitivity and short response time. The detection limit of the Fe3+-selective membrane sensor was about 1.2 times10minus6 mol L-1 and the response time was shorter than 8 s. The linear dynamic range of the Fe3+-selective membrane sensor was between 1.0 times 10minus1 and 8.0 times 10minus6 mol L-1 Fe3+ concentration. The Fe3+-selective membrane sensor exhibited good operational stability for at least two month keeping in dry conditions at 4ndash6 #9702C. It had a reproducible and stable response during continuous standard deviation of 0.34% (n = 30).
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Two diaza-crown ether compounds were synthesized and evaluated as Ag þ -selective carriers in polyvinylchloride (PVC) membrane electrodes of solid-state type. The all-solid-state PVC membrane electrode based on N,N-Dibenzyl-dibenzo-diaza-... more
Two diaza-crown ether compounds were synthesized and evaluated as Ag þ -selective carriers in polyvinylchloride (PVC) membrane electrodes of solid-state type. The all-solid-state PVC membrane electrode based on N,N-Dibenzyl-dibenzo-diaza- 18-crown-6 exhibited a super-Nernstian response (75 � 10 mV per decade) over the concentration range of 1� 10 � 1 to 7� 10 � 6 Mo f Ag þ ion and a detection limit of 3� 10 � 6 M, at a wide range of pH (pH 4-7). The response time of the electrode was fast (less than � 10s), and it can be used for three months without any signifi- cant deviation in potential. The proposed all-solid-state PVC membrane electrodes revealed high selectivity toward Ag þ ion with respect to alkali, alkaline earth, heavy and transition metal ions. A flow-through cell of all-solid-state PVC membrane Ag þ -selective electrode based on N,N-Dibenzyl-dibenzo-diaza-18-crown-6 has also been prepared and applied for flow-injection anal- ysis of Ag þ ion in solution.
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Rural areas of developing countries are particularly reliant on dried cow dung (biomass) for cooking and heating. Biomass combustion releases considerable amounts of particulates with inorganic ions. People in these areas are often... more
Rural areas of developing countries are particularly reliant on dried cow dung (biomass) for cooking and heating. Biomass combustion releases considerable amounts of particulates with inorganic ions. People in these areas are often exposed to high levels of pollutants from biomass combustion. In this regards, this study is focused on the chemical analysis of inorganic ions of indoor airborne particles distributed by combustion of this biomass were made. Inorganic ion concentrations of airborne particles in filter samples were performed by using ion chromatography and potentiometric detection hybrid systems. The mean concentrations of Cl - , NO 2 - , NO 3 - , Br - , CIO 3 - , Na + , K + , NH 4 + , Rb + and Cs + are ranged from 24.53±0.49 to 153.32±3.52, from 0.54±0.01 to 4.34±0.61, from 12.00±0.12 to 49.01±1.10, from 0.21±0.01 to 3.17±0.34, from 0.52±0.01 to 9.98±0.76, from 22.71±0.46 to 141.92±3.25, from 27.30±3.20 to 318.25±34.43, from 14.51±1.17 to 194.11±9.27, fro...
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In this study, a simple, fast, stable and low-cost potentiometric determination method is recommended for the evaluation of 1,1-diphenyl-1-picrylhydrazil radical (DPPH•) scavenging activity, which is one of the antioxidant activity tests.... more
In this study, a simple, fast, stable and low-cost potentiometric determination method is recommended for the evaluation of 1,1-diphenyl-1-picrylhydrazil radical (DPPH•) scavenging activity, which is one of the antioxidant activity tests. For this purpose, a new type of solid-state-contact potentiometric polyvinyl chloride (PVC) membrane sensor was developed. Gallic acid compound, which is sensitive to the DPPH•, was used as the active ingredient in the membrane structure of the sensor. The potentiometric behavior of the developed DPPH•-selective PVC membrane sensor was characterized. The detection limit of the developed sensor was obtained as 2.3 µg/mL. The sensor can measure at low volumes with its high selectivity. The measurement results obtained were in accordance with the results of the spectroscopic method in the literature. The developed DPPH•-selective PVC membrane sensor was quickly dipped directly into the plant extracts and successfully used in test measurements of DPPH• scavenging activity.
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This work deals with the development of micro-size potentiometric calcium-selective electrode. A simple and rapid potentiometric method of determining calcium concentration, based on 10,19-Bis[(octadecylcarbamoyl) methoxyacetyl]-... more
This work deals with the development of micro-size potentiometric calcium-selective electrode. A simple and rapid potentiometric method of determining calcium concentration, based on 10,19-Bis[(octadecylcarbamoyl) methoxyacetyl]- 1,4,7,13,16–pentaoxa-10,19-diazacycloheneicosane, is described. For this aim, calcium-selective polyvinylchloride (PVC) membrane was prepared by coating on the surface of solid-contact. Calcium-selective PVC membrane electrode does not contain internal reference electrode and solution. The potentiometric performance of calcium-selective PVC membrane electrode (selectivity constant, liner working range, detection limit, response time, pH working range, repeatability, lifetime, and time dependent potential decay) was determined using computer controlled measurement system in static conditions. The results showed that the calcium-selective electrode exhibited good reproducibility in calcium determination.
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The extracellular urease from Arthrobacter creatinolyticus was partially purified by ammonium sulfate precipitation and immobilized on PAN [poly(acrylonitrile-methylmethacrylate-sodium vinylsulfonate)] membrane. The urease immobilized PAN... more
The extracellular urease from Arthrobacter creatinolyticus was partially purified by ammonium sulfate precipitation and immobilized on PAN [poly(acrylonitrile-methylmethacrylate-sodium vinylsulfonate)] membrane. The urease immobilized PAN membrane exhibited an activity of 97.92U/cm(2) under the optimum conditions of 1.0% enzyme concentration, 15% glutaraldehyde, 24h immobilization time and temperature of 4°C. The changes in surface morphology of the membrane after immobilization were studied by SEM and ATR-FTIR analysis. Immobilized membrane was associated with potentiometric electrode for calibration of biosensor and the results showed a linear response for wide range of urea concentration from 1 to 100mM. The immobilized urease had good storage stability for a period of 70days at 4°C and could be effectively reused for 13cycles. Urease immobilized membrane was also employed in analysis of urea spiked milk samples.
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A new PVC membrane potentiometric sensor for Ag(I) ion based on a recently synthesized calix[4]arene compound of 5,11,17,23‐tetra‐tert‐butyl‐25,27‐dihydroxy‐calix[4]arene‐thiacrown‐4 is developed. The electrode exhibits a Nernstian... more
A new PVC membrane potentiometric sensor for Ag(I) ion based on a recently synthesized calix[4]arene compound of 5,11,17,23‐tetra‐tert‐butyl‐25,27‐dihydroxy‐calix[4]arene‐thiacrown‐4 is developed. The electrode exhibits a Nernstian response for Ag(I) ions over a wide concentration range (1.0×10−2−1.0×10−6 M) with a slope of 53.8±1.6 mV per decade. It has a relatively fast response time (5–10 s) and can be used for at least 2 months without any considerable divergence in potentials. The proposed electrode shows high selectivity towards Ag+ ions over Pb2+, Cd2+, Co2+, Zn2+, Cu2+, Ni2+, Sr2+, Mg2+, Ca2+, Li+, K+, Na+, NH4+ ions and can be used in a pH range of 2–6. Only interference of Hg2+ is found. It is successfully used as an indicator electrode in potentiometric titration of a mixture of chloride, bromide and iodide ions.
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ABSTRACT In this study, a novel potentiometric sensor that is highly selective to Zn2+ ions is described. A highly selective and sensitive all-solid-state poly(vinyl chloride) membrane Zn2+ sensor, using... more
ABSTRACT In this study, a novel potentiometric sensor that is highly selective to Zn2+ ions is described. A highly selective and sensitive all-solid-state poly(vinyl chloride) membrane Zn2+ sensor, using 7,16-dibenzyl-1,4,10,13-tetraoxa-7,16-diazacyclooctadecane as an ionophore, has been prepared. The best performance was obtained with the sensor having a membrane composition of 4.0% ionophore, 33.0% poly(vinyl chloride), 62.0% Bis(2-ethylhexyl) sebacate (BEHS) and 1.0% potassium tetrakis (p-chlorophenyl) borate (KTpClPB). The sensor exhibits a Nernstian slope of 28.0 ± 2.0 mV/decade in a wide linear concentration range of 1.0 × 10−5 to 1.0 × 10−1 M and detection limit of this sensor is 1.17 × 10−6 M. The developed potentiometric sensor showed a relatively fast response time of 5 s, good reproducibility and stability. The proposed sensor revealed good selectivity over a wide variety of other cations. The working pH range of this sensor is 4.0–11.0. The developed zinc(II)-selective sensor was successfully applied to the direct zinc determination in different water samples and drug sample. The potentiometric results for the drug sample was compared with inductively coupled plasma spectrometry. The proposed zinc(II)-selective electrode can be successfully employed as an indicator electrode in potentiometric titration with EDTA.
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Domestic and industrial water pollution is a serious environmental problem. Because metal ions are used in industrial processes such as mining, metal coating, electroplating, medicine and battery production, many metals and heavy metals... more
Domestic and industrial water pollution is a serious environmental problem. Because metal ions are used in industrial processes such as mining, metal coating, electroplating, medicine and battery production, many metals and heavy metals can cause industrial water pollution. Generally, the determination of these metals is made by instrumental devices. Potentiometric ion selective sensors have been extensively studied by analytical chemists for many years due to their advantages. The developed potentiometric sensors have been used successfully in environmental sample analysis and different sensors have been developed till today and introduced into the literature. In this review, we investigated potentiometric sensor studies which have been successfully applied to the developed wastewater samples.