Hydrogen ion-selective poly(vinyl chloride) membrane electrode based on a calix[4]arene.

A hydrogen ion-selective poly(vinyl chloride) membrane electrode was constructed using 5,11,17,23-tetra-tert-butyl-25,26,27,28-tetracyanomethoxycalix[4]arene as a neutral carrier. The electrode showed an apparent Nernstian response in the 2-11.5 pH range with a slope of 54.0 +/- 0.2 mV/pH at 20 +/- degrees C. This electrode showed a rapid response of the emf to changes in the pH, high ion selectivity with respect to lithium, sodium and potassium, and characteristics similar to those reported for the conventional pH glass membrane electrode. It can be used as a potentiometric indicator electrode in hydrofluoric acid solutions. The effects of iodide, thiocyanate, perchlorate and bromide on the characteristics of the electrode were also considered.     

一种新的适合低pH范围的中性载体PVC膜电极的研究

设计并合成了Ｎ－十八烷基水杨醛亚胺（ＯＤＳＡＩ）,Ｎ－十八烷基苯甲醛亚胺（ＯＤＢＡＩ）两种新的亚胺化合物,并以此为中性载体,制成了ＰＶＣ膜ＰＨ电极。此电极在ＰＨ０．６－８．５的范围内,对氢离子呈现很的能斯响应,电极斜率为５２ｍＶ／ｐＨ。     

Thiocyanate ion-selective PVC membrane electrode based on N,N'-ethylene-bis(4-methylsalicylidineiminato)nickel(II).

A highly selective poly(vinyl chloride) (PVC) membrane electrode based on an N,N'-ethylene-bis(4-methyl-salicylidineiminato) nickel(II) [Ni(EBMSI)] complex as a carrier for a thiocyanate-selective electrode is reported. The influences of the membrane composition, pH and possible interfering anions were investigated based on the response properties of the electrode. The electrode exhibited a good Nernstian slope of -58.9 +/- 0.7 mV decade(-1), over a wide pH range of 3.5 - 8.5 and a linear range of 1.0 x 10(-6) - 1.0 x 10(-1) M for thiocyanate. The detection limit of electrode was 3.1 x 10(-7) M SCN(-). The selectivity coefficients determined by a fixed interference method (FIM) indicate that a good discriminating ability towards the SCN- ion compared to other anions. The proposed sensor had a fast response time of about 5 - 15 s and could be used for at least 3 months without any considerable divergence in the potential. It was applied as an indicator electrode in the titration of thiocyanate with Ag+ and in the potentiometric determination of thiocyanate in saliva and urine samples.     

A hydrogen ion-selective poly(aniline) solid contact electrode based on dibenzylpyrenemethylamine ionophore for highly acidic solutions.

Hydrogen-ion selective solid contact electrodes based on tribenzylamine, dibenzylnaphthalenemethylamine, and dibenzylpyrenemethylamine ionophores were prepared. With these electrodes, we showed that the response ranges were influenced by the number of phenyl rings in the ionophores. The lower limits for a linear pH response in acidic solutions were pH 2.50, 0.65, and 0.50, respectively. As the number of phenyl rings in the ionophores increased, the slopes of the EMF responses of these electrodes did not change significantly, but their response extended toward an acidic range (shifted to pH 0.50). Thus, their dynamic response range became wider. A solid contact electrode with dibenzylpyrenemethylamine ionophore, in particular, showed the best selectivity, from the interference of cations and anions, and the best reproducibility of the EMF. This electrode was stored in Tris buffer solutions, artificial serum, and hydrofluoric acid solutions for one month without any loss of performance. Their response time was 8 s. Satisfactory results were obtained when it was tested directly with artificial serum (in pH range 6.0 - 8.5) and hydrofluoric acid.     

Potentiometric behavior of N,N,N',N'-tetrabenzylmethylenediamine-based hydrogen ion-selective electrodes

H(+)-ion selective electrodes (H(+)-ISE) based on N,N,N',N'-tetrabenzylalkylenediamine (alkylene: methylene, ethylene, propylene, hexylene) are prepared. We are compared with their response potentials to carbon numbers between diamino groups. They were showed linear selective to hydrogen ion in the range of pH 1.5-9.0, 2.5-9.0, 3.5-9.0 and 4.0-9.0, and their Nernstian slopes were 57.3, 53.5, 57.4 and 56.1 mV pH(-1) at 20+/-0.2 degrees C (theoretical value: 58.2 mV pH(-1)), respectively. The interference effect on the cations were measured to alkali metal ions, alkaline earth metals ions. Selectivity coefficients were measured by the mixed-solution method. Among all electrodes the N,N,N',N'-tetrabenzylmethylenediamine (TBMDA)-based electrode has shown the best selectivity in acidic solution.     

Fabrication of a multilayer film electrode containing porphyrin and its application as a potentiometric sensor of iodide ion

A novel iodide ion-selective electrode has been produced based on a molecular deposition technique in which water-soluble porphyrin was alternatively deposited with water-soluble polypyrrole on a 2-aminoethanethiol modified silver electrode. The potentiometric response is independent of pH of the solution between pH 1 and 7, while it is dependent on the nature of the medium. The electrode has a linear dynamic range between 1.6x10(-6) and 0.1 M with a Nernstian slope of 59 mV/decade and a detection limit of 1.0x10(-6) M in acetate buffer (0.1 M, pH 4.6). The electrode has the advantages of low resistance, short conditioning time and fast response.     

Chemically modified electrode based on poly[tetra(4-aminophenyl)porphyrin] as a pH sensor

A chemically modified platinum electrode with coated poly[tetra(4-aminophenyl)porphyrin] has been used as a potentiometric pH sensor. It gives a linear response over the pH range 1.5-13.7 with a slope of 55 mV/pH (at 20 degrees ). The sensor has fair resistance to erosion of hydrofluoric acid and to interference of a coexisting redox couple. The sensor can be used for pH determination and end-point indication for potentiometric titration of hydrofluoric acid with sodium hydroxide. The a.c. impedance of the polymer membrane has also been studied.     

Coated wire silver-ion selective electrode based on a N,N'-bis(2-thienylmethylene)-1,2-diaminobenzene.

A novel membrane coated platinum-wire electrode (MCPWE) based on N,N'-bis(2-thienylmethylene)-1,2-diaminobenzene (BTMD) for highly selective determination of Ag+ ion has been developed. The influences of membrane composition and pH on the potentiometric responses of electrode were investigated. The potentiometric responses are independent of the pH of the test solution in the range of 5.0 - 9.0. The electrode shows a linear response for Ag+ ion over the concentration range of 1.0 x 10(-60 to 1.0 x 10(-1) M with a lower detection limit of 6.0 x 10(-7) M. The electrode possesses a Nernstian slope of 59.7 mV decade(-1) and a fast response time of < or = 17 s and can be used for at least 2 months without any observable deviation. The proposed electrode displayed very good selectivity for Ag+ ion with respect to NH4+ and alkali, alkaline earth and some common transition metal ions. The practical utility of the electrode has been demonstrated by its use as the indicator electrode in the potentiometric titration of an AgNO3 solution with a NaI solution and in determination of the silver content of a developed radiological film.     

Fabrication of a covalently attached multilayer film electrode containing cobalt phthalocyanine and its application as a potentiometric sensor of iodide ion

Construction of a highly stable covalently attached multilayer film electrode containing cobalt phthalocyanine was achieved by UV irradiation of ionic self-assembled multilayer films of diazo-resins (DAR) and cobalt phthalocyanine tetrasulfonic acid (CoTsPc) tetrasodium salt. The modified electrode had good potentiometric response to iodide ion. The potentiometric response was independent of the pH of the solution between pH 2.5 and 6.0, while it was dependent on the nature of the buffer media. The modified electrode had a linear dynamic range between 4.7×10⁻⁶ M and 0.1 M with a Nernstian slope of 58.8 mV per decade and a detection limit of 3.5×10⁻⁶ M in acetate buffer (0.1 M, pH 4.6). The modified electrode also exhibited a fast response, good stability and repeatability.     

电位传感器聚(1,2-二氨基苯)膜化学修饰电极——Ⅰ.电极制备方法的研究

本文报道在[NiFe(CN)_6]~(2-/1)化学修饰膜上电化学聚合生成聚(1,2-二氨基苯)膜化学修饰电极的制备方法,实验结果表明该电极制备方法简便、性能稳定、电极电位对溶液pH值变化敏感,在pH4～10范围内电位响应与pH呈直线关系,斜率为54mV,具有作为pH传感器的前景。     

Preparation of a novel iodide-selective electrode based on iodide-miconazole ion-pair and its application to pharmaceutical analysis.

An iodide-miconazole ion-paired complex was used as a suitable ion-exchanger for the preparation of a plasticized-PVC membrane electrode. Among different solvent mediators tested, dioctylsebacate exhibited the proper response characteristics, including Nernstian slope of the calibration curve, fast response time and good reproducibility of the emf values. The electrode exhibits a Nernstian slope of -59.8 +/- 0.5 mV decade(-1) for I- ion over a concentration range of 1.0 x 10(-5) - 1.0 x 10(-2) M with a limit of detection of 7.0 x 10(-6) M. The electrode displays a good selectivity for I- with respect to a number of inorganic and organic species. It canbe used over a pH range of 2.5 - 8.5. The membrane sensor was successfully applied to the determination of iodide in water samples and blood serum, as well as in pharmaceutical products such as iodoquinol and thyroxin.     

Nickel(II) selective membrane potentiometric sensor using a recently synthesized mercapto compound as neutral carrier

A PVC membrane electrode for Ni²⁺ ions based on a recently synthesized mercapto compound, as an ionophore was prepared. The electrode exhibits a Nernstian slope of 28-30 mV per concentration decade at wide concentration range of (1.0×10⁻²-1.0×10⁻⁷ M). It has a fast response time of <15 s and can be used for at least 4 weeks. The potentiometric response is independent of the pH of the test solution in the pH range 5-8.5. The proposed electrode revealed good selectivities over a wide variety of other cations including alkali, alkaline earth, transition and heavy metal ions. It was successfully applied to the direct determination and potentiometric titration of nickel ion with EDTA.     

Intra- and Inter-molecular Sulf- hydryl Hydrogen Bonding: Facilitating Proton Transfer Events for Determination of pH in Sea Water

This work presents the electrochemical response of a 2-(methylthio)phenol glassy carbon based electrode for a promising voltammetric pH sensor in both buffered and low-buffered solutions. Electropolymerization of the redox species was performed with the resulting polymer presenting a Nernstian response in buffered media, with a sensitivity of 51 mV/pH unit. The effectiveness of the sulfhydryl bond to facilitate proton transfer from the bulk solution to the phenol molecules has been confirmed, providing an accurate pH measurement of 8.28 in sea water media, compared to that measured with a calibrated glass pH probe of 8.30.     

A novel pH sensing membrane based on an ionic liquid-polymer composite

A novel pH sensing membrane was developed that consists of the ionic liquid n-cetylpyridinium hexafluorophosphate (CPFP), poly(vinyl chloride), and quinhydrone. The membrane is stable and flexible and can be easily deposited on the electrode. Electrochemical impedance spectroscopy was used to study the interfacial charge transfer of this membrane. Compared to a traditional plasticizer-based membrane electrode, the new electrode possesses excellent potentiometric characteristics for monitoring pH, such as a response time of less than 10 s, high sensitivity, stability, and reproducibility. The response is almost Nernstian, with a slope of ?57.5?±?0.2 mV pH^?1 in the pH range from 2 to 9.5. The new electrode was used for direct monitoring of pH in real food samples.

双安息香缩三乙四胺双核钴硫氰酸根的离子电极研究

季铵盐型阴离子选择性电极由于其电位选择性往往表现出Hofmeister顺序,故使其应用受到限制,因此,研究呈现反Hofmeister行为的阴离子选择性电极已成为离子电极研究领域中重要的研究方向之一。近年来,人们研制出了以金属配合物为中性载体且呈现反Hofmeister行为的阴离子选择电极,本实验室也分别研究了以Schiff碱金属配合物及二氮杂四烯基金属配合物为载体的碘离子和水杨酸根离子电极,但上述电极多数是以单核金属配合物为载体,以双核金属配合物作为载体的电极则很少。     

Chromium(III) Ion Selective Electrode Based on Oxalic Acid Bis(Cyclohexylidene Hydrazide)

A poly(vinyl chloride) membrane sensor based on oxalic acid bis (cyclohexylidene hydrazide) as membrane carrier was prepared and investigated as a Cr(III)‐selective electrode. The electrode reveals a Nernstian behavior (slope 19.8±0.4 mV decade^?1) over a wide Cr(III) ion concentration range 1.0×10^?7–1.0×10^?2 mol dm^?3 with a very low limit of detection (i.e., down to 6.3×10^?8 mol dm^?3). The potentiometric response of the sensor is independent of the pH of the test solution in the pH range 1.7–6.5. The electrode possesses advantage of very fast response, relatively long lifetime and especially good selectivity to wide variety of other cations. The sensor was used as an indicator electrode, in the potentiometric titration of chromium ion and in the determination of Cr(III) in waste water and alloy samples.     

Flow injection analysis of sulfite ion with a potentiometric titanium phosphate-epoxy based membrane sensor

A novel pH sensor suitable for use in both aqueous and non-aqueous mediums is reported. The sensor is derived from polymer modified electrode obtained from electrochemical polymerisation of aniline in dry acetonitrile containing 0.5 M tetraphenyl borate at 2.0 V versus Ag/AgCl. The light yellow colour polymer modified electrode obtained under the present experimental condition has been characterised by scanning electron microscopy (SEM). The pH sensing of polymer modified electrode in both aqueous and non-aqueous mediums is examined and reported. As the typical examples, we used weak acid (acetic acid) and weak base (ammonium hydroxide) as analytes. The acetic acid is analysed in both aqueous and dry acetonitrile whereas ammonium hydroxide is analysed only in aqueous medium. The analysis in aqueous medium is conducted in 1 mM Tris-HCl buffer pH 7.0 and also in 0.1 M KCl. The slope of pH sensing is calculated from the data recorded in typical buffers and found to be approximately 86 mV per pH. The application of polymer modified electrode for the construction of urea biosensor is described based on immobilised urease within poly vinyl alcohol (PVA) matrix and also within organically modified sol-gel glass on the surface of polymer-modified electrode. The new urea sensor has shown maximum response of 160 mV at 25 degrees C with a lowest detection limit of 20 muM. The performance of new pH sensor and urea sensor has been studied and reported in this communication.     

Ion-selective electrodes in organic analysis-determination of xanthate

A PVC membrane xanthate-selective electrode has been developed for the direct determination of xanthates of primary and secondary alcohols. The xanthate electrode is highly selective and exhibits a Nernstian response in the range 5.0 x 10(-2)-7.1 x 10(-5)M xanthate with a slope of 58.6 mV per concentration decade. The electrode has a wide working pH range (5.0-11.5), a fast response time (less than 30 sec) and is stable for at least two months.     

Cadmium ion-selective electrode based on tetrathia-12-crown-4

A new polyvinylchloride membrane sensor for Cd(2+) ions based on tetrathia-12-crown-4 as an ionophore was prepared. The sensor exhibits a Nernstian response for cadmium ions over a wide concentration range (4.0 x 10(-7) to 1.0 x 10(-1) M) with a slope of 29+/-1 mV decade(-1). The limit of detection is 1.0 x 10(-7) M (0.01 ppm). It has a fast response time of <10 s and can be used for at least 6 weeks without any divergence in potential. The electrode can be used in the pH range from 2.5 to 8.5. The proposed sensor shows fairly good discriminating ability towards Cd(2+) ion in comparison with some alkali, alkaline earth, transition and heavy metal ions. It was successfully applied for the direct determination of Cd(2+) in solution and, as an indicator electrode, in potentiometric titration of cadmium ions.     

Behavior of a polypyrrole solid contact pH-selective electrode based on tertiary amine ionophores containing different alkyl chain lengths between nitrogen and a phenyl group.

We compared the slopes of the EMF responses and the response range of a solid contact electrode based on a tribenzylamine ionophore with those based on a tris(2-phenylethyl)amine ionophore and a tris(3-phenylpropyl)amine ionophore. Their slopes of the EMF responses showed, respectively, 57.7, 58.1, 59.0 mV pH(-1) (at 20 +/- 0.2 degrees C). Also, the linear pH response dynamic ranges were 2.74-10.63 for tribenzylamine-based SCEs, pH 4.47-12.59 for tris(2-phenylethyl)amine, and pH 4.60-13.24 for tris(3-phenylpropyl)amine. When the slopes of the EMF responses and the response range were considered, as the length of the replaced alkyl chain increased between the nitrogen atom and the phenyl group in the ionophore, though the dynamic range and the slopes of the EMF responses of these electrodes did not show any particularly different results, their response ranges moved toward the alkali range (shifted to pH 14). When it was directly applied to cow's milk (in pH range of 6.0-8.5), we could obtain the same satisfying results. This electrode continuously contacted a Tris 7.50 buffered solution as well as cow's milk for one month without any loss of performance. Also, especially, these electrodes showed very good results, such as stabilization of the base potential as well as the best reproducibility and response time (< 10 s).