State Ion Selective Electrodes Research Articles

The Effect of Polythiophene Transducer Nature on the Performance of All-Solid State Ion-Selective Electrodes

The Effect of Polythiophene Transducer Nature on the Performance of All-Solid State Ion-Selective Electrodes

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.

Stable Solid-State Microfabricated Potentiometric Sensor Based on Chitosan- Prussian Blue Nanocomposite Film for Amlodipine Selective Detection

Solid state ion-selective electrodes have a grown importance in advanced detection techniques especially with exploiting different solid contact transducing substances. Nowadays, various approaches focus on producing simple, sensitive, durable and significantly stable electrodes. Lower cost of production could be achieved by employing simple, economical and efficient materials in their fabrication. Herein, a solid state microfabricated copper electrode was firstly designed from a reasonably priced and easily fabricated copper printed circuit boards followed by applying chitosan-Prussian blue nanocomposite layer. Finally, amlodipine sensing membrane was added resulting in construction of an amlodipine sensing microfabricated solid-state electrode. The designed electrode was characterized by being miniaturized, durable, portable, easily fabricated, affordable and highly stable over 60 d with a potential drift value of 600 μV h−1. The microfabricated electrode revealed promising results upon the direct analysis of amlodipine besylate and the responses showed a good linear Nernstian pattern in the dynamic range of 1.0 ×10−5.5 to 1.0 ×10−3 mol l−1 with a slope of 55.1 mV/decade. The detection limit was found to be 2.0 ×10−6 mol l−1. Selective determination of the drug was successfully achieved in presence of its degradation product without any sample preparation steps.

Inkjet-Printed Sulfide-Selective Electrode.

Inkjet printing technology has emerged as an alternative manufacturing method for low-cost production of electrodes. Despite significant progress, there is still a lack in the production of ion-selective electrodes. Herein, the two-step fabrication of the first inkjet-printed sulfide-selective electrode (IPSSE) is described. The two-step fabrication consists of printing a silver electrode followed by an electrochemical deposition of sulfide to produce a second kind electrode (Ag/Ag2S). The performance of this novel device was tested using potentiometric measurements. Nernstian response (-29.4 ± 0.3 mV·decade-1) was obtained within concentrations of 0.03-50 mM with a response time of ∼3 s. Furthermore, river/sea-spiked environmental samples and samples from a bioreactor for sulfate reduction to sulfide were measured and compared against a commercial sensor giving no significant differences. The IPSSE described in this work showed good reproducibility and durability during daily measurements over 15 days without any special storage conditions. Considering all the current challenges in inkjet-printed ion-selective electrodes, this different fabrication approach opens a new perspective for mass production of all-solid state ion-selective electrodes.

An ionic liquid-based sensor for diclofenac determination in water

ABSTRACTThis paper details a miniaturised, solid state ion-selective electrode selective for diclofenac. The sensor comprises a novel ionic liquid electroactive material – an imidazolium–diclofenac ion associate. The ion associate is present in a plasticised poly(vinyl chloride) (PVC) membrane on planar carbon electrodes, with an intermediate poly(3,4-ethylenedioxythiophene) layer. The sensitivity and selectivity of the sensor were determined using chronopotentiometric methods. In response to diclofenac, a slope of −53.3 ± 3.6 mV/dec was observed. A limit of detection of 2.90 × 10−3 g L−1 is reported, with a linear range of 3.18 × 10−3 g L−1 to 3.18 g L−1. The sensors show good selectivity towards diclofenac against pertinent interferent molecules, with a response time of <15 s.

Recent progress of all solid state ion selective electrode

All solid state ion selective electrodes (ISE) is a significant research orientation in the study of potentiometric sensors. With the development of science, traditional liquid junction ISEs exhibit many disadvantages. The study of all solid state ISE has been attracted more and more attention in recent decade. They have been applied in so many fields, such as clinical test, environment monitoring and industry analysis. According to the different ion electron transfer principle of all solid state transducer, all solid state ISEs are classified into three types: double layer capacitance all solid state ISE, redox capacitance all solid state ISE, and double layer and redox mixed capacitance all solid state ISE. In this mini-review, the progress of the above three types of all solid state ISE were introduced and summarized. Meanwhile, the responding mechanism of every type all solid state ISE was discussed. The development tendency of all solid state ISE was also predicted.

Preparation and Evaluation of a Stable Solid State Ion Selective Electrode of Polypyrrole/Electrochemically Reduced Graphene/Glassy Carbon Substrate for Soil Nitrate Sensing

Preparation and Evaluation of a Stable Solid State Ion Selective Electrode of Polypyrrole/Electrochemically Reduced Graphene/Glassy Carbon Substrate for Soil Nitrate Sensing

Highly hydrophobic solid contact based on graphene-hybrid nanocomposites for all solid state potentiometric sensors with well-formulated phase boundary potentials

The properties of solid contact (SC) transducer are crucial for obtaining stable solid state ion selective electrodes (ISEs). We report in this work that the hybrid nanomaterial composed of graphene and sliver tetrakis[3,5-bis(trifluoromethyl)phenyl]borate (AgTFPB), designated graphene&AgTFPB, can be sandwiched between an ion selective membrane (ISM) containing TFPB− and a silver conducting substrate (CS) and effectively work as the SC transducer to provide ion-to-electron translation. Thus developed solid state ISEs, designated Ag/graphene&AgTFPB/K+-ISM electrodes, demonstrated a Nernstian response to K+ with a slope of 56.46 (±0.25)mV/decade (n=5) in a concentration range of 10−5.2–10−2.9M with a detection limit of 10−5.73M, as well as a sufficient stability against O2, CO2 and light. Furthermore, the Ag/graphene&AgTFPB/K+-ISM electrodes displayed a standard electromotive force (EMF) of 550.42 (±1.34)mV with a batch-to-batch deviation of 1.26mV. We believe that the superior potential stability and reproducibility can be ascribed to the graphene&AgTFPB nanocomposites SC. We believe that the doped AgTFPB can provide the ion-to-electron transduction via the Ag/AgTFPB/TFPB− redox conversion at the SC/CS interface and the ion-exchange equilibrium of TFPB− at the ISM/SC interface. Thus, the overall potential difference across the potentiometric measurement cell can be theoretically formulated in terms of thermodynamic equilibrium at two interfaces. Moreover, the highly hydrophobic nature of graphene&AgTFPB nanocomposites can also substantially suppress the formation of water layer.

Engine oil acidity detection using solid state ion selective electrodes

Lubricating oil of moving parts is a critical factor for the performance and longevity of cars and industrial engines. The lubricant degradation occurring during application can be detrimental to the proper operation of lubricated machines if the oil is not changed in a timely manner. However, the oil degradation process is often influenced by a number of parameters, such as the operating temperature and contamination. This offers a challenge to oil monitoring technologies. This study investigates the feasibility of detecting changes in oil acidity using ion selective electrodes (ISE) fabricated using thick-film (TF) screen printing technology. The working electrode is a TF ruthenium oxide (RuO2) ISE; the reference electrodes are three different types of TF reference electrodes and commercial glass pH reference electrode. Artificially degraded oil samples from oxidation tests and model oils produced by adding acid have been used for the evaluation of the sensors. Acid Number (AN) of all oil samples was obtained using conventional titration method. The results show that the TF electrodes responded linearly to the change in oil acidity under different temperatures. Their sensitivity in detecting oil acidity in the model oils is found to be much higher than that of the commercial electrode. Initial analysis also shows that the sensor responses decrease as the temperature increases.

A Multifunctional Microgripper Capable of Simultaneous Single Cell Manipulation and Associated Ion Sensing

ABSTRACTThe successful modification of the tips of a cellular microgripper into ion selective electrodes capable of sensing calcium ions at concentrations as low as 8x10-5 M is described. The modification involves applying the process of adding the components of all solid state ion selective electrodes. Specifically, poly(3,4-ethylenedioxythiophene) (PEDOT) is added to a gold electrode protruding from the microgripper tip; this is then coated with a poly(vinyl chloride) PVC based calcium selective membrane. Excellent Nernstian response was observed from our devices, with calibration slopes of 29.5 ± 2.5 mV/dec.

Analysis of Simulated Martian Regolith Using an Array of Ion Selective Electrodes

AbstractA prototype miniature array of polymer membrane and solid state ion selective electrodes was developed for the purpose of performing an in‐situ analysis of the soluble ionic species in Martian regolith (soil). The array contains a total of 27 electrodes for K+, Na+, Ca2+, Mg2+, NH$\rm{ {_{4}^{+}}}$, Ba2+, NO$\rm{ {_{3}^{-}}}$, Cl−, and Li+, each in triplicate. Barium electrodes were used to indirectly monitor sulfate through precipitation by the addition of barium chloride while the lithium electrodes served as a reference for the array by having a constant lithium concentration as a background for all solutions. The array was tested with several types of simulants, soils, and sawdust from a Mars meteorite, all with varying salt content, meant to approximate the various hypotheses regarding the ionic composition of the Martian soil. The activities of anions and cations determined with the array were compared to ion chromatography data.

A New Potentiometric Photocurable Membrane Selectiveto Anionic Surfactants

The preparation of photocurable polymer membranes selective to anionic surfactants and their application to all-solid state ion-selective electrodes are reported. A preliminary trial employing CHEMFET devices is also shown. Membranes are based on a urethane-acrylate polymer, and use 2-cyanophenyl octyl ether (CPOE), a plasticizer compatible with the photocuring process. These membranes are highly selective to the anionic surfactants assayed while common inorganic anions did not interfere. An optimization methodology is proposed for their formulation, suited to the final application. Several membrane compositions were obtained, using between 44 and 48 % (w/w) CPOE. A membrane with a general-purpose formulation is fully characterized, and we show calibration results for anionic surfactants such as dodecylbenzenesulfonate (DBS−), tetrapropylenebenzenesulfonate and dodecylsulfate, or cationic surfactants such as Hyamine 1622 and cetyltrimethylammonium ion. With the primary ion DBS− we verified a 58.1 mV/dec sensitivity, a linear response between 1×10−3 M and 3×10−6 M, a detection limit corresponding to 0.26 ppm DBS− (7.9×10−7 M) and a slope precision of 2.8 % RSD between days.

Potentiometric selectivity of p-doped polymer films

It was observed previously that anion-exchanging polymer films doped with common anions such as Cl −, NO 3 − are rather inselective. The reasons for observed lack of selectivity are still obscured. In this paper, the potentiometric selectivity of polymer films is discussed. This interpretation is based on the previously presented model for potentiometric responses of p-doped polymer layers, and on the theory of selectivity of solid state ion-selective electrodes. Both the differences and similarities between the two systems are indicated. The equations given are used for the calculations of selectivity coefficients for polypyrrole films in presence of nitrate, chloride and thiocyanate ions. In the absence of a diffusion potential inside the membrane, the observed selectivity coefficients can be interpreted in terms of the formation of hypothetical sparingly soluble salts between polymer solution anions. It was shown that this applies to the nitrate interference on PPyCl membranes. This system is analogous to bromide interference on an AgCl membrane. According to the theoretical consideration, the K Cl,NO 3 poly was equal, within the range of experimental error, to 1/ K NO 3,Cl poly. Although the system is modelled with idealising assumptions the experimental results are in good accordance with prediction of the theory.

Ni-Zn ferrite spinel: characterization and evaluation of its suitability for ion selective electrodes

Ion selective electrodes (ISE) constitute an important place in the expanding areas of analytical research. This is not surprising, because ISE offer a wide variety of possible applications in many disciplines and, most importantly, they are relatively inexpensive and easy to operate [1, 2]. In recent years, a variety of solid state membrane electrodes have been developed, each of which has its own impact on the analysis of various species [3—5]. The work reported here was aimed at exploring the possibility of utilizing Ni—Zn ferrite spinel for solid state ion selective electrodes and involved the characterization of Ni—Zn ferrite spinel by surface analytical techniques, electrical conductivity measurement and potential response studies. A 1:1 molar ratio of NiO/ZnO and Fe2 03 was used to prepare the Ni—Zn ferrite spinel. In all cases the Fe2 03 content was fixed at 1.0 molar and the molar ratios of NiO and ZnO were varied in such a way that their total content was 1.0 molar. Five different molar ratio combinations of NiO and ZnO, namely 0.1 and 0.9; 0.3 and 0.7; 0.5 and 0.5; 0.7 and 0.3; and 0.9 and 0.1, were chosen for the present study and the spinel samples prepared using each proportion were assigned a formula based on the amount of NiO, ZnO and Fe203 present in them. The NiO, ZnO and Fe203 (in suitable molar ratios) were thoroughly mixed and ground with 50% polyvinyl alcohol (PVA). A weighed quantity of 300 mg of the mixed and ground sample was then compacted and pressed at 8 tcm2. Sintering was carried out in an automatic temperature control programmed electric furnace at four different temperatures, 1100, 1200, 1350 and 1450 °C. During sintering the temperature of the furnace was increased at a rate of 200 °C h—' and after attaining the desired temperatures the samples were retained for 2 h. Two kinds of cooling procedures were adopted: (i) rapid cooling in air and (ii) slow cooling in furnace. The prepared Ni—Zn ferrite samples were characterized by scanning electron microscopy (SEM), energy dispersive X-ray spectrometry (EDX) and Xray diffraction (XRD). EDX analysis was performed with a Link Analysis AN 185S model using a tungsten filament and at an accelerated potential of 20 kV. The measurements were made for a period of 100 s. Based on the integrated intensity values, the amount of each element present was calculated and the oxygen content was obtained after subtracting the total metal content. XRD measurement was carried out with a Shimadzu model VD-IA X-ray diffractometer using CuKa and a nickel filter at an accelerated voltage of 30 kV. The diffraction patterns obtained were analysed after the ASTM (file card no. 8-234) set for the Ni—Zn ferrite spinel. SEM evaluation of the samples were made after they were suitably polished (mechanically by fine abrasive papers and 1 tm and 0.3 tim size alumina powder, followed chemically by 86% phosphoric acid) and sputtered with a gold coating. The electrical conductivity of the prepared Ni—Zn ferrite samples was measured using a two-point probe method described elsewhere [6]. The potential response studies were made with the use of a pH/ion meter. Disk samples of Ni—Zn ferrite were mounted on the bottom of a glass tube of 9 cm length, 1.4 cm diameter and having an inner diameter of 0.5 cm using epoxy resin. The prepared electrodes were tested for any leakage, as such a leakage can drastically affect the potential response. A 0.1 M solution of KC1 was used as internal filling solution for the electrode. Ag/AgC1 electrode and saturated calomel electrodes served as the internal and external reference electrodes. The potential response of the Ni—Zn ferrite electrodes towards the Bi3 and 2_ in the concentration ranges from 10 to iO M were assessed. The interference for the analysis of Bi3* and S2 from various cations and anions was also studied. The composition of the Ni—Zn ferrite spinel prepared at various sintering temperatures was determined using EDX. There was not much change in the Ni, Zn, Fe and 0 contents of the spinel up to a sintering temperature of 1200 °C. However, there was a considerable decrease in the zinc content at higher sintering temperatures, and at 1450 °C this decrease in zinc content amounted to about 50% of the initial zinc content used before sintering (Table I). The loss of zinc at higher sintering temperatures is obvious at all proportions of the NiO, ZnO and Fe2 03 used in the present study and hence can very well be attributed to the sublimation process. XRD measurements were performed on the prepared spinel samples to confirm their formation and crystal structure. For all proportions used in this

Kinetic and mechanistic study of the copper(II)–oxamate complexation, monitored by the CuII solid state ion selective electrode

AbstractThe complexation process of copper(II) with oxamates was followed by the use of a copper solid state ion selective electrode. The shape of the recorded potential vs. time was interpreted on the basis of the known kinetic expressions for a two step reaction, monitoring the consumption of the reagent. The potential changes of the electrode are attributed to a decrease in the copper concentration. The curves are of an exponential form with two distinct parts, the first due to the intermediate activated complex, which is produced very rapidly, and the second is due to the slow formation of the soluble chelate. The effects of various parameters are studied in relation to the retardation of the first step. The reaction rate constant k, the equilibrium constant K* for the first step, the stability constant K, the activation energy Ea, the change in enthalpy, and the product (pZ) of the frequency and steric factors were determined. On the basis of the above data, a mechanistic scheme for this complexation reaction is proposed.

Surface characterization of lead ion selective electrodes: Life after adsorption

The interaction of interfering ions with the lead ion selective electrode membrane is much more complex than comparable interactions on other solid state ion selective electrode membranes. The possible mechanisms of interaction are identified, and a theoretical model, supported by experimental results and developed with the goal of predicting them, is described.

Side effects in measurements of selectivity coefficients of solid state ion selective electrodes

The influence of various factors such as solubility, the oxidation of the membrane, and the contamination of the solution, on the experimental values of the selectivity coefficients of solid state sulphide ion selective electrodes is discussed. A new method for the evaluation of very small selectivity coefficients, based on the addition of reagents forming complexes or insoluble salts with the main ion, is proposed. By means of this method, selectivity coefficients for silver, copper, cadmium and lead ion selective electrodes have been determined, which are in far better agreement with thermodynamic values than those described in the literature.

Effect of addition of main ion to carrier solution in potentiometric flow-injection measurements with solid state ion-selective electrodes

Flow-injection measurements were performed using chloride, fluoride, iodide and copper(II)-selective electrodes. A pronounced effect of addition of main ion to the carrier solution was observed for the fluoride- and iodide-selective electrode. Super-Nernstian slope observed for the fluoride- and copper(II)-selective electrode in the absence of the sensed ion in the carrier solution decreased to Nernstian values in the presence of the measured ion in the carrier solution. This phenomenon is explained by different response times at different concentrations of the sensed ion.

The dependence of the galvani potential difference between water and nitrobenzene on salt partition: A model for liquid state ion-selective electrodes

The concepts of ion-exchange and salt partition between immiscible electrolyte solutions at equilibrium have been employed as a model to explain the potential—activity characteristics of liquid state ion-selective electrodes based on dissolved “ion-exchangers”. Using the partition data of nitrobenzene/water system, we show the theoretical potential response of the system to the salt composition and discuss the selectivity behaviour.

New Solid State Ion-Selective Electrode Body

Abstract A new design for a solid state ion-selective electrode body is described. Various pressed pellet membranes can be used as the sensing element. Changing function is rapid and convenient with this design. Response curves for membranes composed of Ag2S, PbS-Ag2S and AgI-Ag2S are given and compared with commercial designs.