Theory and applications of ion-selective electrodes Part III

This review of ion-selective electrodes is arranged in the same way as Parts I and II. The continuous growth of the whole subject should be noted. Theory has particularly progressed through mechanistic studies. Among new types of electrodes, ISFET systems have become important. Among new applications of both solid and liquid membrane electrodes, the fluoride electrode still predominates, closely followed by potassium electrodes. In the field of biological and medical applications, the steady growth is significant. More than 800 papers published between mid-1976 and the end of 1978 are mentioned in the review.     

Theory and applications of ion-selective electrodes: Part 7

This review on ion-selective is arranged in the same way as earlier reviews of this series. The whole subject continues to grow steadily. The most discussed field is that of analysis of body-fluid cations. About 850 papers published between Spring 1985 and Spring 1987 are mentioned, covering the theory of membrane processes, technology, electrolysis at liquid/liquid interfaces, fixed-site electrodes, liquid-membrane electrodes, potentiometric biosensors and miscellaneous systems.     

Theory and applications of ion-selective electrodes: Part 5

This review of ion-selective electrodes is arranged in the same way as earlier reviews in this series. The whole subject is steadily growing. More attention has been given to automatic methods of analysis with ion-selective electrodes, electrolysis at the interface of two immiscible electrolyte solutions, and to ion-selective field-effect transistors. The number of publications on traditional subjects like fluoride ion-selective electrodes has dropped. About 700 pagpers published between Spring 1981 and Spring 1983 are mentioned.     

Theory and applications of ion-selective electrodes: Part 6

This review of ion-selective electrodes is arranged in the same way as earlier reviews of this series. The whole subject continues to grow steadily. Considerable attention has been given to clinical analysis of body electrolytes, particularly by means of automatic devices. About 800 papers published between Spring 1983 and Spring 1985 (including several omitted in Part 5) are mentioned, covering the theory of membrane phenomena, technology, fixed-state eletrodes, liquid-membranes electrodes, potentiometric biosensors and miscellaneous systems.     

Theory and applications of ion-selective electrodes part 4

This review of ion-selective electrodes is arranged in the same way as earlier reviews in this series. The growth of the whole subject approaches a steady state. Some mechanistic studies have deepened theoretical understanding. Better insight into the mechanism of liquid-membrane systems has been gained by electrolysis at the interface of two immiscible electrolyte solutions. In this field some interesting analytical applications are noted. A steady growth is shown by publications on ion-selective field-effect transistors. Otherwise the same proportion is preserved among well-established electrode types. About 800 papers published between the end of 1978 and the beginning of 1981 are mentioned.     

Neutral-carrier-based ion-selective electrodes

Neutral-carrier-based ion-selective electrodes for the assay of alkali and alkaline earth metal cations have advanced to become the most frequently used potentiometric sensors in clinical chemistry. The major developments since the realization of the first potentiometric cell assemblies utilizing electrically neutral complexing agents (valinomycin and the macrotetrolides) in 1966 are presented.     

Coated-wire ion-selective electrodes

Coated-wire ion-selective electrodes were first developed in 1971, and comprise a film of polyvinyl chloride or other suitable polymeric matrix substrate containing a dissolved electroactive species, coated on a conducting substrate (generally a metal, although any material with conductivity substantially higher than that of the film can be used). Electrodes of this sort are simple, inexpensive, durable and capable of reliable response in the concentration range of 10^?1 to 10^?6 M for a wide variety of both organic and inorganic cations and anions. The principles on which these electrodes are based, as well as their application to a variety of analytical problems, will be discussed.     

Investigation of ion-selective electrodes with neutral ionophores and ionic sites by EIS. I. Theory

Models of an ion selective electrode involving an ionophore and mobile sites in a membrane are proposed. The first model, called the phase boundary potential model, supposed thermodynamic equilibrium; it allows the concentrations of the various species to be calculated. Then, a kinetic model, which takes into account the ionic transfer at the membrane|solution interfaces, was derived. The impedance of the membrane was calculated. It shows that a membrane with nernstian behavior shows only one capacitive loop in the impedance diagram, which is related to the conductivity and dielectric properties of the material of the membrane. Non-nernstian behavior is related to slow ionic transfer at the membrane|solution interfaces or/and transport limitation of the species in the membrane. Finite rate constants of the ionic transfer lead to a capacitive loop in the middle frequency range, whereas finite rate transport leads to a diffusional impedance in the low frequency range.     

Amperometric enzyme electrodes: Part I. Theory

The theory of the steady state operation of an amperometric enzyme is derived. The reaction scheme includes diffusion of substrate and product through a membrane, the kinetics of the enzyme substrate reaction and the electrochemical regeneration of the enzyme. A simple diagnostic plot is derived which allows the rate limiting process to be identified, and the balance between the transport of substrate through the membrane and the enzyme and electrochemical kinetics to be determined. The effects of inhibition by the accumulation of product behind the membrane are also considered.     

The surface morphology of ion-selective membrane electrodes : Part I. Studies on silver iodide-based silicone rubber membrane electrodes

Electron micrographs, and micrographs of electron absorption and silver and iodine distribution on the surfaces and cross-sections of silver iodide-based silicone-rubber membranes showing Nernstian electrode response are presented. An electron microprobe analyzer was used. The electrochemical effects of concentrated (0.6 M) potassium iodide solutions and iron(III) hydroxide or iron(III) ions, are described. The phenomena are interpreted on the basis of the results obtained by electrochemical, atomic absorption and electron microprobe analysis.     

Determination of ethaverine and papaverine using ion-selective electrodes.

Ion-selective poly(vinyl chloride) membrane electrodes for the opium alkaloids papaverine and ethaverine are presented. The electrode membranes contain ion pairs of the alkaloids with the anionic counter ion tetraphenylborate. The detection limits for all electrodes were approximately 2 x 10(-6) mol dm-3 at pH 5.0 in 100 mmol dm-3 buffered solutions and the measured slopes were close to the values theoretically expected. The selectivity coefficient observed for the ethaverine-tetraphenylborate electrode is 10(-1.1) with respect to papaverine. The suitability of the membranes for single-use electrodes is discussed.     

Analytical applications of quaternary ammonium halides using ion-selective electrodes: A review

Summary The analytical applications of quaternary ammonium halides are reviewed. These compounds are used as titrants in the potentiometric determination of a variety of inorganic and organic anions including soaps and surfactants. Various liquid-membrane electrodes such as the perchlorate, fluoroborate, nitrate, and calcium electrodes may be used as sensors and, in some cases, solid-state electrodes such as the cyanide (iodide) electrode. The most important titrants are cetyltrimethylammonium bromide and chloride and cetylpyridinium chloride.

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Analytische Anwendungen von quaternären Ammoniumhalogeniden mit Hilfe von ionen-selektiven Elektroden. Ein Überblick

Zusammenfassung Quaternäre Ammoniumhalogenide werden als Titrationsmittel bei der potentiometrischen Bestimmung vieler anorganischer und organischer Anionen, einschließlich von Seifen und oberflächenaktiven Substanzen, verwendet. Verschiedenartige Flüssig-Membran-Elektroden (Perchlorat-, Fluorborat-, Nitrat- und Calciumelektroden) können als Sensoren benutzt werden. Auch Fest-Elektroden (Cyanid, Iodid) kommen in bestimmten Fällen zum Einsatz. Die wichtigsten Titranten sind Cetyltrimethylammoniumbromid und -chlorid sowie Cetylpyridiniumchlorid.

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Work performed under the auspices of the U.S. Department of Energy by the Lawrence Livermore National Laboratory under contract number W-7405-ENG-48

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Parts of this paper were presented at the Anorganisch-Chemisches Institut I der Universität, Frankfurt/Main, on April 23, 1981     

Screen-printed copper ion-selective electrodes

A simple, low-cost and reproducible method for the mass production of potentiometric ion-selective electrodes for copper ions is presented. These planar, strip sensors were obtained by screen-printing. The application of pastes cured at low temperature allows printing of the sensors on low-cost, plastic substrates. The pastes for printing of ion-sensitive thick-film membranes were based on copper (1) and copper (II) sulfides. The analytical characteristics of the thick-film electrodes were compared. The analytical properties (range of determination, sensitivity, selectivity, response time) of the copper (I) sulfide-based sensors were comparable with those for conventional ion-selective electrodes.     

Screen-printed copper ion-selective electrodes

A simple, low-cost and reproducible method for the mass production of potentiometric ion-selective electrodes for copper ions is presented. These planar, strip sensors were obtained by screen-printing. The application of pastes cured at low temperature allows printing of the sensors on low-cost, plastic substrates. The pastes for printing of ion-sensitive thick-film membranes were based on copper (I) and copper (II) sulfides. The analytical characteristics of the thick-film electrodes were compared. The analytical properties (range of determination, sensitivity, selectivity, response time) of the copper (I) sulfide-based sensors were comparable with those for conventional ion-selective electrodes. Received: 12 January 2000 / Revised: 13 March 2000 / Accepted: 16 March 2000     

Bipolar pulse conductometric monitoring of ion-selective electrodes: Part 2. Studies with the fluoride-selective electrode

Bipolar pulse conductometric monitoring of the fluoride ion-selective electrode (i.s.e.) is evaluated. It is shown that fluoride ion, in addition to affecting the electrode potential, also can have two effects upon the total resistance of the electrode. Fluoride ion can enter a gel layer on the surface of the doped lanthanum fluoride crystal; solution concentrations as low as 10^-9 M fluoride can significantly decrease the gel resistance. Fluoride concentrations in the potentiometric working range of the i.s.e. can also increase the electrode resistance. The conductometric detection limit is 2–4 decades lower than the potentiometric detection limit. However, because of the resistance factors, the conductometric curve is not monotonic, and shows a maximum at a fluoride concentration in the vicinity of the potentiometric detection limit. The two resistive changes possible have different time dependences; the decrease of the gel layer resistance becomes predominant at long measurement times, while the increase of the crystal resistance predominates within the first minute of exposure to solution. Hydroxide is shown to affect the i.s.e. potential and lower the gel layer resistance. Response time to changes in fluoride concentration are less than 15 s and do not show the strong concentration dependence observed potentiometrically. The i.s.e. is shown to have a slightly lower resistance to fluoride entering the crystal than to fluoride leaving it. The small resistive dependence on direction of ion migration may indicate a directional dependence of activation energy for ion transport across the membrane solution interfaces.     

Properties of naproxen ion-selective electrodes

Naproxen membrane electrodes based on different plasticizers and the quaternary ammonium salts (QASs) dimethyldidecylammonium bromide, methyltrioctylammonium chloride, or tetraoctylammonium chloride, were prepared. The following basic parameters were investigated for the optimal electrode: measurement range (10⁻⁴ − 10⁻¹ mol L⁻¹), slope of the linear range of the calibration curve (−58.3 mV decade⁻¹), limit of detection (6.0 × 10⁻⁵ mol L⁻¹), lifetime (2.5 months), dependence of the electrode potential on pH (5.5 − 9.0), reproducibility of potential (1.2 mV) and selectivity coefficients in relation to selected organic and inorganic anions. The electrode was utilized for determination of naproxen in tablets by the calibration curve method and the standard addition method.      

Sulphonamides as ionophores for ion-selective electrodes. I

A series of new compounds: di-sulphonamides and mono-sulpho-mono-carboxy-di-amides has been synthesized. Comparison of the ionophoric properties of these compounds in liquid membrane electrodes was performed and the correlation between the chemical structure and potentiometric ionselectivity has been studied.     

Current trends in ion-selective electrodes

Recent advances in the development of ion-selective electrodes have led to the production of new potentiometric sensors with superb selectivity. These electrodes are frequently good enough to allow for analyses in complex, multicomponent samples such as blood or urine.