Potentiometric Response Characteristics Research Articles

Potentiometric determination of the local anesthetic procaine in pharmaceutical samples

In this study, a new potentiometric sensor was developed for the determination of the local anesthetic drug procaine in pharmaceutical samples. Procaine (Pr)–Tetraphenlyborate (TPB) ion–pair was synthesized and used as a sensor material. Potentiometric sensors using the synthesized ion pair (Pr–TPB), poly(vinyl chloride) (PVC) and o–nitrophenyloctyl ether (o–NPOE) in different proportions were prepared and their performance properties were tested. Among the prepared sensors, the best potentiometric response characteristics were obtained with the sensor composition Pr–TPB:PVC:o–NPOE in the ratio of 6.0:32.0:62.0 (w/w %). The new procaine sensor developed in the present study had a near–Nernstian behavior of 54.1 ± 3.3 mV/per decade and a low detection limit of 3.18 × 10−5 mol L−1 in the concentration range of 1.0 × 10−1–1.0 × 10−4 mol L−1. Additionally, the sensor had a response time of less than 10 s and could work in a wide pH range for two different concentration values without being affected by pH changes. Finally, the new procaine potentiometric sensor was used to detect procaine in injection samples and successfully determined procaine concentrations with high recoveries.

Bridged EGFET Design for the Rapid Screening of Sorbents as Sensitisers in Water-Pollution Sensors.

We further simplify the most 'user-friendly' potentiometric sensor for waterborne analytes, the 'extended-gate field effect transistor' (EGFET). This is accomplished using a 'bridge' design, that links two separate water pools, a 'control gate' (CG) pool and a 'floating gate' (FG) pool, by a bridge filled with agar-agar hydrogel. We show electric communication between electrodes in the pools across the gel bridge to the gate of an LND150 FET. When loading the gel bridge with a sorbent that is known to act as a sensitiser for Cu2+ water pollution, namely, the ion exchanging zeolite 'clinoptilolite', the bridged EGFET acts as a potentiometric sensor to waterborne Cu2+. We then introduce novel sensitisers into the gel bridge, the commercially available resins PurometTM MTS9140 and MTS9200, which are sorbents for the extraction of mercury (Hg2+) pollution from water. We find a response of the bridged EGFET to Hg2+ water pollution, setting a template for the rapid screening of ion exchange resins that are readily available for a wide range of harmful (or precious) metal ions. We fit the potentiometric sensor response vs. pollutant concentration characteristics to the Langmuir-Freundlich (LF) model which is discussed in context with other ion-sensor characteristics.

Potentiometric Carboxylate Sensors Based on Carbazole-Derived Acyclic and Macrocyclic Ionophores

Solid-contact ion-selective electrodes with carbazole-derived ionophores were prepared. They were characterized as acetate sensors, but can be used to determine a number of carboxylates. The potentiometric response characteristics (slope, detection limit, selectivity, and pH sensitivity) of sensors prepared with different membrane compositions (ionophore, ionophore concentration, anion exchanger concentration, and plasticizer) were evaluated. The results show that for the macrocyclic ionophores, a larger cavity provided better selectivity. The sensors exhibited modest selectivity for acetate but good selectivity for benzoate. The carbazole-derived ionophores effectively decreased the interference from lipophilic anions, such as bromide, nitrate, iodide, and thiocyanate. The selectivity, detection limit, and linear range were improved by choosing a suitable plasticizer and by reducing the ionophore and anion exchanger concentrations. The influence of the electrode body’s material upon the composition of the plasticized poly(vinyl chloride) membrane, and thus also upon the sensor characteristics, was also studied. The choice of materials for the electrode body significantly affected the characteristics of the sensors.

Fabrication of Zn(II) Selective Polyvinyl Chloride Membrane Electrode based on N,N'-bis(1-hydroxynaphthalene-2-carbaldehyde)-o-phenylenediamine as an Ionophore: Experimental and Theoretical Approaches

A new ion-selective polyvinyl chloride membrane electrode based on Schiff base [N,N′-bis(1-hydroxynaphthalene-2-carbaldehyde)-o-phenylenediamine] as an ionophore is successfully worked out as sensor for Zn(II) ions. The electrode shows excellent potentiometric response characteristics and displays a linear emf versus log[Zn2+] response over a wide concentration range of 1.0 × 10–7‒0.1 M with nernstian slope of 29.0 ± 0.1 mV/decade with the detection limit of 1.8 × 10–8 M. The sensor exhibits the advantages of fast response time (<10 s). The lifetime of the sensor is about 3 months. It was used as an indicator electrode in the potentiometric titration of Zn(II) with EDTA and for the determination of Zn(II) in pharma samples. The results were validated by using quantum mechanical density functional theoretical calculations. Theoretical studies proved prominent affinity of ligand towards Zn(II) ion.

Enhancing the biocompatibility of Sodium Membrane Electrodes by Using Chitosan-CuO and Chitosan-CuO-Heparin Composite Membranes

We investigate the effect of introducing chitosan CuO-nanoparticle and heparin loading chitosan CuO nanoparticle composite membranes to PVC based sodium selective membrane electrode to enhance its biocompatibility and reduce its highly thrombogenicity. The potentiometric responses of three sets of electrodes were studied: (1) conventional PVC membrane electrode, (2) conventional PVC membrane electrode sandwiched with chitosan-CuO membrane (CH-CuO-PVC), and (3) conventional PVC membrane electrode sandwiched with chitosan-CuO-heparin membrane (CH-CuO-H-PVC). Potentiometric response characteristics of the CH-CuO-PVC and CH-CuO-H-PVC membrane electrodes (e.g., detection limit, linear range, response slope, and selectivity coefficients) were found to be comparable to that of the conventional PVC-based sodium electrodes. Biocompatibility was assessed for all membranes (PVC and CH-CuO-PVC and CH-CuO-H-PVC) through platelet adhesion protocol. SEM and platelet counts have shown that CH-CuO and CH-CuO-H have improved biocompatibility compared to the classical PVC membranes.

Potentiometric Sensors for Iodide and Bromide Based on Pt(II)-Porphyrin.

Pt(II) 5,10,15,20-tetra(4-methoxy-phenyl)-porphyrin (PtTMeOPP) was used in the construction of new ion-selective sensors. The potentiometric response characteristics (slope and selectivity) of iodide and bromide-selective electrodes based on (PtTMeOPP) metalloporphyrin in o-nitrophenyloctylether (NPOE), dioctylphtalate (DOP) and dioctylsebacate (DOS) plasticized poly(vinyl chloride) membranes are compared. The best results were obtained for the membranes plasticized with DOP and NPOE. The sensors have linear responses with near-Nernstian slopes toward bromide and iodide ions and good selectivity. The membrane plasticized with NPOE was electrochemically characterized using the EIS method to determine its water absorption and the diffusion coefficient into the membrane.

Fabrication of Pb(II) Selective Polymeric Membrane Electrode Based on 2,2’[Propane-1,3-Diylbis(Oxy)]Dibenzaldehyde as an Ionophore. J Anal Bioanal Tech

2,2'-[propane-1,3-diylbis(oxy)]dibenzaldehyde has been explored as an ionophore and fabricated in a polyvinylchloride (PVC)-based membrane. The electrode shows excellent potentiometric response characteristics and displays a linear log [Pb(II)] versus emf response over a wide concentration range of 1.2 × 10-7 M to 1.0 × 10-1 M with detection limit 3.3 × 10-8 M and having nernstian slope of 29.06 mV/decade. Potential response remains almost unchanged at pH range of 3.0-8.0. The electrode shows fast response time of <10 s and a lifetime of four months. It shows good selectivity for Pb(II) ions over the other cations. The complexation 2,2'-[propane-1,3- diylbis(oxy)]dibenzaldehyde and Pb(II) cation was studied spectrophotometrically in 1:1 DMF:H2 O mixed solvents. Spectra shows the strong interaction between Ionophore and Pb(II) ion. The electrode can also be used as an indicator electrode in potentiometric titration of Pb(II) ions with standard chromate solution and its determination in real samples.

A novel modified screen-printed electrode with triazole surfactant assembled on silver nanoparticles for potentiometric determination of uranium

Potentiometric modified screen-printed electrodes were developed for UO2(II) determination using a triazole-derivative alone (MSPE) or self-assembled on silver nanoparticles- (SNPs-MSPE). The electrodes exhibited excellent potentiometric response characteristics with Nernstian slopes of 26.70 ± 1.02 and 29.90 ± 0.88 mV decade−1 and detection limits of 1.00 × 10−7 and 6.10 × 10−10 mol L−1 for MSPE and SNPs-MSPE, respectively. The electrodes showed fast response times and independent response over a wide pH range. Effect of solution temperature was investigated in the range of 10-60 °C. The optimized electrodes revealed good selectivity for UO2(II) over various interferant and were successfully employed to detect UO2(II) in different real samples.

Research on the Improvement on the Performance of Thermal Underwear Based on the Demands of Chinese Consumers

ZnO-nanoparticle Coated Multiwall Carbon Nanotube as a New Sensing Element for Highly Sensitive Potentiometric Determination of Thiosulfate Ion Here, we are reporting the response properties of a simple and useful potentiometric thiosulfate-selective electrode based on multiwall carbon nanotubes (MWCNTs) decorated with ZnO nanoparticles as sensing element. We successfully decorated the MWCNTs by using sol-gel process, which has not been reported to prepare such a decoration before. The ZnO-MWCNTs were characterized by XRD, SEM and TEM techniques. After optimization the composition requirements for construction the best electrode, the potentiometric response characteristics of the electrochemical sensor was examined for determination of thiosulfateanion in aqueous solutions. A Nernstian response of 30.3 ± 0.1 mV/dec with a detection limit of 1.24×10-7 M, a linear dynamic range of 1.35×10-7 to 1.45×10-1 M of thiosulfate and a response time of about 3 min are of good performance factors for the proposed electrode. The electrode demonstrated a reasonable repeatability and high selectivity towards the thiosulfate ion over the other tested anions in the solution.

Anion-selective electrodes based on solidified 1,3-dihexadecylimidazolium ionic liquids with halide and pseudohalide anions

In this study screen-printed solid-state electrodes using low-melting ionic liquids with cation of 1,3-dihexadecylimidazolium and such anions as chloride, iodide, and thiocyanate were developed. Potentiometric response and electrochemical characteristics of ion-selective electrodes in KCl, KI, and KSCN solutions were studied. All sensors exhibited sensitivity toward the corresponding anions, the slopes close to Nernstian ones, low detection limits (3.0∙10−6M for SCN−), and high selectivity in the presence of the extraneous anions. Operation time of the sensors was not less than one year. The applicability of the developed electrodes for the potentiometric determination of iodide in pharmaceuticals and thiocyanate in human saliva was demonstrated.

Enhancing biocompatibility of some cation selective electrodes using heparin modified bacterial cellulose

Bacterial cellulose (BC) and heparin-modified bacterial cellulose (HBC) were utilized to enhance the biocompatibility of highly thrombogenic PVC-based potassium and calcium membrane electrodes. Three types of membrane electrodes were prepared: (1) conventional PVC electrode (control), (2) PVC-based electrode sandwiched with bacterial cellulose membrane (BC-PVC), and (3) PVC-based electrode sandwiched with heparin-modified bacterial cellulose membrane (HBC-PVC). The potentiometric response characteristics of the modified potassium and calcium membrane electrodes (BC-PVC and HBC-PVC) were compared with those of the control PVC-based potassium and calcium selective electrode, respectively. Response characteristics of the modified membrane electrodes were comparable to the control PVC membrane electrode. The platelet adhesion investigations indicated that (BC) and (HBC) layers are less thrombogenic compared to PVC. Therefore, use of BC or HBC would enable the enhancement of the biocompatibility of PVC-based membrane electrodes for potassium and calcium while practically maintaining the overall electrochemical performance of the PVC sensing film.

Development of an improved ligand mimetic calibration system for the analysis of iron(III) in seawater using the iron(III) chalcogenide glass ion selective electrode: A combined mechanistic and analytical study

Further to previous work on a seawater ligand mimetic calibration system for the electroanalysis of iron(III) in seawater using the iron chalcogenide glass ion-selective electrode (ISE), this study utilized alternative blends of synthetic ligands, in order to fine-tune and optimize the calibration response characteristics of this sensor for the electroanalysis of free iron(III) in seawater. Herein, an alternative calibration system (ACS) was derived using a mixture of 10−4M iron(III) chloride, 10−4M ethylenediaminetetraacetic acid (EDTA), 10−3M copper(II) sulphate, 5×10−3M ethylenediamine (EN) and 0.60M sodium chloride yielding a Nernstian response of about 30mV decade−1. The electroanalysis of free iron(III) in seawater using the ACS generated a free iron(III) level commensurate with the predicted organic and inorganic speciation of iron(III) in seawater. Furthermore, electrochemical impedance spectroscopy (EIS), synchrotron radiation X-ray photoelectron spectroscopy (SR-XPS) and near-edge X-ray absorption fine structure (NEXAFS) spectroscopy have demonstrated that the surface reaction processes of this membrane in the ACS are comparable to those experienced in a natural seawater matrix. Ultimately, this study demonstrated that the ACS can mimic the surface chemistry and concomitant potentiometric response characteristics of the iron(III) sensor in seawater, enabling reliable electroanalyses of free iron(III) in seawater.

Potentiometric Response Characteristics of Oxide-Coated Gallium Electrodes in Aqueous Solutions

This paper reports on the potentiometric response characteristics of gallium electrodes coated with native or anodic oxide layers in aqueous solutions. Solid metallic gallium electrodes were prepared by cooling liquid gallium monoliths supported either on planar silicon substrates or incorporated within glass capillaries. These metallic gallium electrodes showed potentiometric pH responses with a slope of ca. -38mV/pH in the pH range between 3 and 9. The potentials measured could originate from redox processes involving surface oxide that was formed as a result of reactions between the metallic gallium and water (and/or OH−), as observed using scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX). Similar potentiometric measurements were examined for planar and capillary-incorporated gallium electrodes that were anodized in ice-cooled aqueous H2SO4 at 10V. Although the resulting nanoporous anodic oxide-coated electrodes did not initially show potentiometric pH responses, they exhibited pH responses with a smaller response slope (ca. -30mV/pH; pH 3∼9) after potentiometric measurements in a solution of pH ≤ 3. This observation could be explained by the acid-induced dissolution of an oxide-based barrier layer that passivated the underlying gallium electrode. This explanation was compatible with the observation of an additional gallium oxide layer over the nanoporous anodic oxide after the potentiometric pH measurements. Interestingly, in contrast to the metallic gallium electrodes, the anodic oxide-coated electrodes exhibited potentiometric Nernstian responses to SO42− at ≥ 10−4M, reflecting the presence of sulfate doped into the oxide during the anodization. These results provide fundamental knowledge required to design miniaturized electroanalytical probes based on gallium electrodes.

Electrochemical Determination of Perchlorate Ion By Polymeric Membrane and Coated Graphite Electrodes Based on Zinc Complexes of Macrocyclic Ligands

The quick determination of trace quantities of ionic species, by simple methods, is of special interest in analytical chemistry. Ion selective electrodes based on solvent polymeric membranes with incorporation of ion carriers are shown to be very useful tools for chemical, clinical and environmental analyses as well as in process monitoring [1-3]. In addition to the cation-selective electrodes, recently the design and synthesis of sensory molecules for anion-selective electrodes has become a challenging subject [4]. For a truly anion-selective electrode, a strong interaction between the ionophore and the anion is required in order to complex anion in a selective fashion. Potentiometric response of the membranes doped with these complexes is believed to be based on the coordination of analyte anion with carrier molecule.The electrode characteristics and selectivities of PVC-based perchlorate selective coated graphite electrode (CGE) and polymeric membrane electrode (PME) incorporating the synthesized zinc complexes of 6,7:13,14-Dibenzo-2,4,9,11-tetramethyl-1,5,8,12-tetraazacyclotetradecane-1,4,6,8,11,13-hexaene (I1) and 6,7:13,14-Dibenzo-2,4,9,11-tetramethyl-1,5,8,12-tetramethylacrylate-1,5,8,12-tetraazacyclotetradecane-6,13-diene (I2) are reported here. Several membranes having different compositions of PVC, plasticizers, ionic additives and ionophores were fabricated and the best response was observed for the membrane having composition I2: PVC: BA: HTAB in the ratio of 7: 32: 59: 2 (w/w; mg). The PME shows good performance characteristics in terms of detection limit of 5.4 × 10− 7 mol L− 1, working concentration range of 8.3 × 10− 7 to 1.0 × 10− 2 mol L− 1 and slope 58.7 ± 0.3 mV decade− 1 of activity. Thus the CGE with same membrane composition was prepared and its potentiometric response characteristics were compared. The electrode exhibits Nernstian slope for perchlorate ions over wide concentration ranges i.e. 8.3 × 10-7 to 1.0 × 10-2 mol L-1 (with PME) and 1.0 × 10-7 to 1.0 × 10-2 mol L-1(with CGE) and response time of 12 s and 9 s for PME and CGE respectively. The proposed electrodes generated constant potentials in the pH range of 3.0-8.0 for PME and 2.5-9.0 for CGE. The high selectivity of CGE for perchlorate ions permits its use in the determination of perchlorate ions in various samples such as water and human urine samples.Fig. 1. (a) Structure of zinc complex of 6,7:13,14-Dibenzo-2,4,9,11-tetramethyl-1,5,8,12-tetraazacyclotetradecane-1,4,6,8,11,13-hexaene (I1) (b) Structure of zinc complex of 6,7:13,14-Dibenzo-2,4,9,11-tetramethyl-1,5,8,12-tetramethylacrylate-1,5,8,12-tetraaza-cyclotetradecane-6,13-diene (I2).Table 1. Response characteristics of the perchlorate ion-selective electrodes based on PME and CGEPropertiesPotentiometric ResponsePMECGEOptimized membrane composition (w/w; mg)(I2: PVC: BA : HTAB) ≡ (7: 32: 59: 2)(I2: PVC: BA : HTAB) ≡ (7: 32: 59: 2)Working concentration range ( mol L-1)8.3 ´ 10-7 -1.0 ´ 10-2 1.0 ´ 10-7–1.0 ´ 10-2 Detection limit ( mol L-1)5.4 ´ 10-7 8.4 ´ 10-8 Slope (mV decade-1 of activity)58.7 ± 0.359.3 ± 0.2Response time (s)129Life span30 days65 dayspH range3.0 - 8.02.5 - 9.0

Polymeric plasticizer extends the lifetime of PVC-membrane ion-selective electrodes

The nature of the plasticizer plays a pivotal role in the analytical performance of polymer membrane ion sensors. Conventional plasticizers suffer leaching or migration from the membrane and exudation, both of which could limit the lifetime of sensors based on plasticized membranes. Herein, we describe the use of polyester sebacate (PES), a model polymeric plasticizer, in the preparation of poly (vinyl chloride) (PVC) membrane ion-selective electrodes (ISEs) using valinomycin as ionophore. PVC membrane electrodes plasticized with polyester sebacate demonstrated potentiometric response characteristics that compared favorably to ones plasticized with the conventional and similarly structured plasticizer bis(2-ethylhexyl) sebacate (DOS). Increasing the content of polyester sebacate in the membrane enhanced the response and improved the selectivity of valinomycin-based ISEs toward potassium over sodium. Various methods, including electrochemical impedance spectroscopy, UV-vis spectroscopy, dark field optical microscopy, and potentiometry were employed to study the effect of plasticizer on the leaching of the membrane components and the lifetime of both DOS- and PES-plasticized membranes. PES-plasticized electrodes maintained Nernstian response and high selectivity for more than four months, an improvement over DOS-plasticized membrane electrodes. This was attributed to enhanced retention of the membrane components because of the high polymeric nature of the polyester sebacate. These characteristics suggest that polyester sebacate is a good candidate to replace the conventional plasticizers in preparing PVC membrane electrodes with longer lifetime.

Cyanex based uranyl sensitive polymeric membrane electrodes

Novel uranyl selective polymeric membrane electrodes were prepared using three different low-cost and commercially available Cyanex extractants namely, bis(2,4,4-trimethylpentyl) phosphinic acid [L1], bis(2,4,4-trimethylpentyl) monothiophosphinic acid [L2] and bis(2,4,4-trimethylpentyl) dithiophosphinic acid [L3]. Optimization and performance characteristics of the developed Cyanex based polymer membrane electrodes were determined. The influence of membrane composition (e.g., amount and type of ionic sites, as well as type of plasticizer) on potentiometric responses of the prepared membrane electrodes was studied. Optimized Cyanex-based membrane electrodes exhibited Nernstian responses for UO₂(2+) ion over wide concentration ranges with fast response times. The optimized membrane electrodes based on L1, L2 and L3 exhibited Nernstian responses towards uranyl ion with slopes of 29.4, 28.0 and 29.3 mV decade(-1), respectively. The optimized membrane electrodes based on L1-L3 showed detection limits of 8.3 × 10(-5), 3.0 × 10(-5) and 3.3 × 10(-6) mol L(-1), respectively. The selectivity studies showed that the optimized membrane electrodes exhibited high selectivity towards UO₂(2+) ion over large number of other cations. Membrane electrodes based on L3 exhibited superior potentiometric response characteristics compared to those based on L1 and L2 (e.g., widest linear range and lowest detection limit). The analytical utility of uranyl membrane electrodes formulated with Cyanex extractant L3 was demonstrated by the analysis of uranyl ion in different real samples for nuclear safeguards verification purposes. The results obtained using direct potentiometry and flow-injection methods were compared with those measured using the standard UV-visible and inductively coupled plasma spectroscopic methods.

Reduction of thrombogenicity of PVC-based sodium selective membrane electrodes using heparin-modified chitosan

Heparin-modified chitosan (H-chitosan) membrane was utilized to enhance biocompatibility of sodium selective membrane electrode based on the highly thrombogenic polyvinyl chloride (PVC). Sodium ion sensing film was prepared using PVC, sodium ionophore-X, potassium tetrakis(chlorophenyl)-borate, and o-nitrophenyloctylether. The PVC-based sensing film was sandwiched to chitosan or H-chitosan to prevent platelet adhesion on the surface of PVC. Potentiometric response characteristics of PVC-chitosan and PVC-H-chitosan membrane electrodes were found to be comparable to that of a control PVC based sodium-selective electrode. This indicates that chitosan and H-chitosan layers do not alter the response behaviour of the PVC-based sensing film. Biocompatibility of H-chitosan was confirmed by in vitro platelet adhesion study. The platelet adhesion investigations indicated that H-chitosan film is less thrombogenic compared to PVC, which could result in enhancement of biocompatibility of sodium selective membrane electrodes based on PVC, while maintaining the overall electrochemical performance of the PVC-based sensing film.

Potentiometric detection and removal of copper using porphyrins

BackgroundCopper is an essential trace element with a great importance in industry, environment and biological systems. The great advantage of ion-selective sensors in comparison with other proposed techniques is that they are measuring the free metal ion activity which is responsible for their toxicity. Porphyrins are known to be among the best ionophores in formulation of ion-selective sensors.ResultsA symmetrically substituted meso-porphyrin, namely: 5,10,15,20-tetrakis(4-allyloxyphenyl)porphyrin (TAPP) was used in the construction of a new copper selective-sensor and was also tested for the removal of copper from waste waters. The potentiometric response characteristics (slope and selectivity) of copper-selective electrodes based on TAPP in o-nitrophenyloctylether (o-NPOE), dioctyl phtalate (DOP) and dioctyl sebacate (DOS) plasticized with poly(vinyl chloride) membranes are compared.ConclusionsThe best results were obtained for the membrane plasticized with DOP. The sensor has linear response in the range 1x10-7 – 1x10-1 M with 28.4 ± 0.4 mV/decade near-Nernstian slope towards copper ions and presents good selectivity. Due to its chelating nature, the same porphyrin was also tested for the retention of copper from synthetic copper samples, showing a maximum adsorption capacity of 280 mg/g.

Neodymium(III) PVC Membrane Electrodchemical Sensor Based on N‐benzoylethylidene‐2‐aminobenzylamine

The N‐benzoylethylidene‐2‐aminobenzylamine (BEA) was used as a suitable ionophore in construction of neodymium ion selective electrode. The electrode with composition of 30% PVC, 58% solvent mediator (NB), 2% ionophore (BEA) and 10% anionic additive (OA) shows the best potentiometric response characteristics. The Nd3+ sensor exhibits a Nernstian slope of 21.2 ± 0.2 mV decade-1 over the concentration range of 1.0 × 10-6 to 1.0 × 10-2 mol L-1, and a detection limit of 6.3 × 10-7 mol L-1 of Nd3+ ions. The potentiometric response of the sensor is independent of the solution pH in the range of 2.4–8.5. It has a very short response time, in the whole concentration range (~7 s), and can be used for at least eight weeks. The proposed sensor revealed high selectivity with respect to all common alkali, alkaline earth, transition and heavy metal ions, including members of the lanthanide family other than Nd3+. The Nd3+ sensor was successfully applied as an indicator electrode in the potentiometric titration of Nd3+ ions with EDTA. The electrode was also employed for the determination of the fluoride ion in two mouth wash preparations.

Quantitative monitoring of terbium ion by a Tb3+ selective electrode based on a new Schiff's base

Solution study showed N,N′-bis(5-nitrosalicylidene)-2-aminobenzylamin (L) trends toward Tb3+ ion. Then, it was used as a suitable ionophore in construction of terbium ion selective electrode. The electrode with composition of 30% PVC, 65% solvent mediator (NB), 3% ionophore (L) and 2% anionic additive (NaTPB) shows the best potentiometric response characteristics. It displays a Nernstian behavior (20.1mVdecade−1) over the concentration range 1.0×10−6 to 1.0×10−2molL−1. The detection limit of the electrode is 6.3×10−7molL−1. It has a very short response time (~10s) and a useful working pH range of 2.6–9.4 for at least 2months. The proposed membrane sensor shows excellent discriminating ability towards Tb3+ ions with regard to several alkali, alkaline earth, transition and heavy metal ions. To investigate the analytical applicability of the sensor, it was successfully applied to the determination of terbium in certified reference material.