Construction Of Ion-selective Electrodes Research Articles

Ion-Selective Electrodes with Solid Contact Based on Composite Materials: A Review.

Potentiometric sensors are the largest and most commonly used group of electrochemical sensors. Among them, ion-selective electrodes hold a prominent place. Since the end of the last century, their re-development has been observed, which is a consequence of the introduction of solid contact constructions, i.e., electrodes without an internal electrolyte solution. Research carried out in the field of potentiometric sensors primarily focuses on developing new variants of solid contact in order to obtain devices with better analytical parameters, and at the same time cheaper and easier to use, which has been made possible thanks to the achievements of material engineering. This paper presents an overview of new materials used as a solid contact in ion-selective electrodes over the past several years. These are primarily composite and hybrid materials that are a combination of carbon nanomaterials and polymers, as well as those obtained from carbon and polymer nanomaterials in combination with others, such as metal nanoparticles, metal oxides, ionic liquids and many others. Composite materials often have better mechanical, thermal, electrical, optical and chemical properties than the original components. With regard to their use in the construction of ion-selective electrodes, it is particularly important to increase the capacitance and surface area of the material, which makes them more effective in the process of charge transfer between the polymer membrane and the substrate material. This allows to obtain sensors with better analytical and operational parameters. Brief characteristics of electrodes with solid contact, their advantages and disadvantages, as well as research methods used to assess their parameters and analytical usefulness were presented. The work was divided into chapters according to the type of composite material, while the data in the table were arranged according to the type of ion. Selected basic analytical parameters of the obtained electrodes have been collected and summarized in order to better illustrate and compare the achievements that have been described till now in this field of analytical chemistry, which is potentiometry. This comprehensive review is a compendium of knowledge in the research area of functional composite materials and state-of-the-art SC-ISE construction technologies.

Novel polymeric sensor for ultra-trace determination of cerium (III) based on CoNiFe2O4 nanocomposite

The current study reports a successful cation-selective electrode based on CoNiFe2O4 magnetic nanocomposite to determine the Ce3+ ion. The results revealed this new nanocomposite can be applied as an excellent modifier in lieu of common organic modifiers that are used in the construction of ion-selective electrodes. The replacement of nanocomposite can significantly boost the performance of the electrode compared with organic modifiers. Under optimal conditions, the sensor exhibited a Nernstian slope of roughly 17.5 mV per decade in the linear range of 1.0 × 10−8–1.0 × 10−1 mol/L. Also, the detection limit was 7.0 × 10−9 mol/L. This electrochemical sensor showed a stable potential in 5 s. The optimum pH for electrode operation is in the range of 2–10. Among various interferences ions, this electrochemical sensor manifested high selectivity toward Ce3+ cation. The obtained results in analytical applications demonstrated the excellent ability of this electrode to determine Ce3+ cation via titration with ethylene diamine tetra acetic acid. Moreover, this indicator electrode was used for the measurement of Ce3+ cations in various samples.

Comparative study of nitrate all solid state ion-selective electrode based on multiwalled carbon nanotubes-ionic liquid nanocomposite

Carbon nanotubes have enjoyed unflagging popularity in recent years. They are successfully used in many fields of science, including potentiometry for the construction of ion selective electrodes with solid contact. A new type of SC-ISEs sensitive to nitrate(V) ions using multiwalled carbon nanotubes-ionic liquid nanocomposite was prepared. The effect of the kind of carbon nanotubes on the parameters of SC-ISEs was investigated. The study compares, among others, detection limits, sensitivity and linearity ranges of characteristic curves, and stability of the potential measured for the tested electrodes. Electrochemical impedance spectroscopy and chronopotentiometric techniques were also used as research methods. It was found that the type of carbon nanotubes included in the nanocomposite influences both the metrological and electrical parameters of the obtained solid contact nitrate ion-selective electrode.

Electrocoating Polypyrrole on Gold-Wire Electrode as Potential Mediator Membrane Candidate for Anionic Surfactant Electrode Sensor

The development of polypyrrole as a potential mediator membrane candidate for sodium dodecyl sulfate (SDS) sensor electrode has been investigated. The polypyrrole membrane was synthesized electrochemically from the pyrrole and coated at the surface of a 1.0 mm diameter of the gold-wire electrode. Electropolymerization of pyrrole and coating of the polypyrrole produced was performed by cyclic voltammetry technique in the electrochemical cell containing supporting electrolyte of 0.01 M NaClO4 with an optimum potential range of -0.9 V–1.0 V, the scanning rate of 100 mV/s, an electric current of 2 mA, and running of potential scanning of 10 cycles. By using the similar optimal parameters of cyclic voltammetry, electropolymerization of 0.01 M pyrrole solution containing 0.001 M SDS also produces a polypyrrole membrane coated at the gold-wire electrode surface. These coated electrodes have the potential response-ability toward DS- anions in the concentration range of 10-7 M–10-5 M with a limit of detection of 10-7 M and sensitivity of electrode of 9.9 mV/decade. This finding shows that the SDS solution’s role is as supporting electrolyte and also as a source of DS- dopant during the pyrrole electropolymerization processes. Dopants are trapped in the polymer membrane during the electrochemical formation of polypyrrole and role as ionophores for DS- anion in the analyte solution. A potential response to the electrode phenomena is excellent basic scientific information for further synthesis of conducting polymer and development of conducting polymer-coated wire electrode model, especially in the construction of ion-selective electrode (ISE) for the determination of anionic surfactants with those models.

A simple way to modify selectivity of sodium sensitive electrodes by using organic conductive crystals

An ion-selective membrane is an essential element in the construction of ion-selective electrodes. In this work, some investigations concerned on influence of an ion-selective membrane composition on sodium-selective electrode properties are presented. Several coated-disc sodium-selective electrodes were prepared with the use of sodium ionophore III or sodium ionophore VI, or mixture of these two selective carriers. Membranes with the same compositions were also used to obtain sensors with solid contact transducer layer consisted of 7,7,8,8-tetracyanoquinodimethane (TCNQ) and its sodium radical salt (NaTCNQ). In other polymeric membranes, a whole or some part of ionophore was replaced by NaTCNQ in order to assess the effect of its presence on sodium single-piece electrode characteristics. All kinds of prepared electrodes were tested using potentiometric and chronopotentiometric studies, and significant impact of membrane composition on electrode parameters was observed. Among investigated sensors, TCNQ/NaTCNQ-contacted all-solid-state electrodes exhibited the best analytical and electrical performance due to the presence of the intermediate layer, which simplifies the ion-to-electron transduction process between the ion-sensing membrane and the glassy carbon electrode. Exemplary, these electrodes with sodium ionophore III had a close-to-Nernstian slope (58.63 mV/pNa) in the range from 10−5–10−1-M NaCl and revealed detection limit of 10–5.2 M. However, the mixing of sodium ionophores III and VI in one polymeric membrane led to improved sensitivity and limit of detection (58.79 mV/pNa and 10–5.4 M, respectively). The highest capacitance observed for electrodes with TCNQ/NaTCNQ based on intermediate layer was 139 μF.

Application of nanoparticles in the potentiometric ion selective electrodes

Among the various analytical techniques available, the use of ion-selective electrodes is a wellestablished routine analytical technique. Good ion-selective electrodes (ISEs) possess many advantages over traditional methods for analysis and provide accurate, reproducible, fast, and regular selective determination of various ionic species. Modification of ISEs with nanoparticles has shown interesting ability toward various ions and biological molecules. In this article we review some of developments about applications of nanoparticles in the construction of ISEs in recent years.

KINETIC STUDY OF CHARGE TRANSFER COMPLEXES OF IODINE WITH SOME CROWN ETHERS IN NONAQUEOUS SOLVENTS

ABSTRACT Charge-transfer complexation of iodine with 15-crown-5(15C5), dicyclohexyl-18-crown-6 (DC18C6), benzo-18-crown-6 (B18C6) and dibenzo-24-crown-8 (DB24C8) has been studied in chloroform (CHCl 3 ), Dichloromethane (DCM) and 1,2-dichloroethane (1,2-DCE) solutions at different time. The results indicated immediate formation of an electron donor–electron acceptor complex; which is followed by two relatively slow consecutive reactions. The pseudo-first-order rate constants for the formation of the ionic intermediate and the final product have been evaluated at 25 °C. The rate of formation of product has been measured as a function of time in different halocarbone solvents. The pseudo first order rate constants were evaluated from the absorbance- time data and found to vary in the order of 1,2-DCE >DCM >CHCl 3 . Keywords : Iodine; Charge transfer complex; Spectrophotometry; Kinetic; Crown ether. e-mail: nializadeh@yahoo.com INTRODUCTION Lariat ethers belong to special class of crown ethers with covalency linked side arm(s), which enhance the binding ability of crown ethers towards metal ions. Many investigations have been carried out on applications of crown ethers in several varieties of areas, such as: chemical analysis [1], in construction of ion-selective electrodes [2,3], solid phase in chromatography column [4]. Studies of crown ethers complexation in different solvents show that the thermodynamic and kinetic parameters and even the mechanism of the complexation processes are affected by the nature and composition of the solvent system [5,6]. Crown ethers are macrocyclic ethers known for their ability to form stable and selective inclusion complexes with many metal ions, including alkali and alkaline earth metal cations [7]. The stability of these complexes appears to be related to the macrocycles

Optimizing the analytical performance and construction of ion-selective electrodes with conducting polymer-based ion-to-electron transducers

All-solid-state ion-selective electrodes that use a conducting polymer as the ion-to-electron transducer have emerged as one of the most promising classes of all-solid-state potentiometric sensors in recent years. This is largely because it has many analytical advantages, including high response stability, which is unique in the field of internal-solution-free ion-selective electrodes. This paper reviews the considerable progress that has been made in this area of sensing in recent years, in terms of detection limits, selectivity coefficients and novel construction methods.

The use of hybrid microelectronics in the construction of ionselective electrodes: S. J. Lepavuori and P. S. Romppainen Electrocomponent Sci. Technol. 10, 129 (1983)

The use of hybrid microelectronics in the construction of ionselective electrodes: S. J. Lepavuori and P. S. Romppainen Electrocomponent Sci. Technol. 10, 129 (1983)

The use of hybrid microelectronics in the construction of ion-selective electrodes : S. I. Leppavuori and P. S. Romppainen. Electrocomponent Sci. Technol.10, 129 (1983)

The use of hybrid microelectronics in the construction of ion-selective electrodes : S. I. Leppavuori and P. S. Romppainen. Electrocomponent Sci. Technol.10, 129 (1983)

Determination of nitrate in water with a new construction of ion-selective electrode

A new design of the liquid-state electrode for nitrate ions is proposed. It contains a porous wick soaked with the liquid ion-exchanger, and has no internal reference solution. This electrode was used for nitrate determination of tap water at the level 8–10 p.p.m. The effects of chloride and hydrogencarbonate are eliminated by the addition of silver sulphate and a phosphate buffer, which also maintains constant ionic strength. Precision of a series of measurements is better than 2%, but the results show differences up to 10% compared to the colorimetric brucine procedure.