Coated-wire Ion-selective Electrodes Research Articles

The Coated-Wire Ion-Selective Electrode (CWISE) of Tartrazine Using Chitosan as an Ionophore

Research on the Ion-Selective Electrode (ISE) of coated wire-type tartrazine using chitosan as an ionophore has been developed. The variables used in the manufacture of ISE are membrane composition and immersion time. Meanwhile, the basic characteristics of ISE measured are Nernst value, measurement concentration range, detection limit, and measurement response time. The results showed that ISE tartrazine coated wire type had an optimum membrane composition in a mixture of chitosan: PVC: DOP of 3: 34: 63 (% w/w) and a membrane immersion time 20 minutes. The basic characteristics of ISE produce a Nernst value of 20.976 mV/decade. The measurement concentration range is 1×10-7-1×10-2 M with a detection limit of 2.749×10-7 M or 0.1469 ppm. The response time ranges from 10-60 seconds, with an average of 40 seconds.

Thermodynamic investigation of inclusion complex formation between cetyltrimethyl ammonium bromide (CTAB) and β-cyclodextrin at various temperatures

In this work, the inclusion complex formation between a cationic surfactant, cetyltrimethyl ammonium bromide (CTAB) and β-cyclodextrin was investigated at various temperatures using coated wire ion selective electrodes. Obtained data indicates that inclusion complexes, S(CD) and S(CD)2 have been formed between CTAB and β-CD in aqueous solution. We have used a least mean squares computer fitting program using K1 and K2 as adjustable parameters. Investigation showed that the K1 (first equilibrium constant) for S(CD) formation is greater than K2 (second equilibrium constant) for S(CD)2 formation. The experiments were carried out at different temperatures. Finally thermodynamic parameters of the complexation, i.e. ΔG°, ΔH° and ΔS° have been also calculated. The thermodynamic parameters show that the hydrophobic effect has a very important role in complexation process. The large value of ΔG° indicates that complexation between CTAB and β-CD is very favorable.

Coated Wire Ion Selective Electrode Based on a New Crown Ether for Determination of ${\rm Fe}^{2+}$

A coated wire Fe <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2+</sup> ion selective electrode based on laboratory-synthesized crown ether, as a neutral carrier, was constructed. The effects of different experimental parameters such as the amount of plasticizer, the amount of ionophore, pH of the sample solution, and coexisting ions on the potentiometric responses of the electrode were investigated. The electrode exhibited a Nernstian slope of 29.20±0.87 mV/decade over a wide concentration range of 7.2×10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-7</sup> -6.9×10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-3</sup> M Fe <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2+</sup> . The potentiometric responses were independent of the pH of the test solution in the pH range of 4.6-9.6. The response time and detection limit were found to be 3.0 min and 6.7×10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-7</sup> M, respectively. The electrode revealed good selectivity for Fe <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2+</sup> in the presence of different coexisting cations and anions. It was certified as an indicator electrode by performing a potentiometric titration for a standard sample of Fe <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2+</sup> ion.

Development of coated-wire silver ion selective electrodes on paper using conductive films of silver nanoparticles

Films of silver nanoparticles are used for the first time as an electrical conductor and ion-to-electron transducer to fabricate coated-wire ion selective electrodes (ISEs) on paper. The film of nano silver ink (nano silver film), synthesized from the reduction of AgNO3 by NaBH4, was screen printed on paper. Transmission electron microscopy showed that the synthesized silver nanoparticles (AgNPs) possessed a spherical shape with diameter ca. 5 nm. Energy-dispersive X-ray spectroscopy supported the purity and good stability of the synthesized AgNPs. Nano silver films were sintered at room temperature, 100 °C and 200 °C. Upon increasing the sintering temperature, atomic force microscopy showed that the size of AgNPs of nano silver films increased, but the sheet resistivity decreased. Silver ISEs were then fabricated from nano silver films and o-NPOE-plasticized polymeric membranes containing benzothiazolyl calix[4]arene () as ionophore and KTpClPB as anionic site. The performance of the developed Ag-ISEs was investigated by potentiometric measurements, potentiometric water layer tests, current reversal chronopotentiometry and electrochemical impedance spectroscopy. The coated-wire electrode fabricated from the nano silver film sintering at room temperature showed the best characteristics of Ag-ISEs giving a near Nernstian response slope of 59.7 ± 1.0 mV per decade, 10(-6) to 10(-2) M linear range, detection limit of 4.5 × 10(-7) M, long-term potential stability and good reversibility.

Determination of Water Uptake of Polymeric Ion-Selective Membranes with the Coulometric Karl Fischer and FT-IR-Attenuated Total Reflection Techniques

The water uptake of plasticized poly(vinyl chloride) (PVC) and silicone rubber (SR) based calcium-selective membranes which are commonly used in solid-contact and coated-wire ion-selective electrodes (SC-ISEs and CWEs) was quantified with the oven based coulometric Karl Fischer (KF) technique. Two different membrane types were studied: (1) the plasticized PVC or SR (RTV 3140) membrane matrix without other added membrane components and (2) the full Ca(2+)-selective membrane formulation consisting of the membrane matrixes, potassium tetrakis[3,5-bis(trifluoromethyl)phenyl]borate and calcium ionophore IV (ETH 5234) or calcium ionophore I (ETH 1001). The membranes were contacted for 24 h either asymmetrically from one side or symmetrically from both sides with deionized water (DIW) or 0.1 M solutions of CaCl(2), KCl, or NaCl. It was found that the water uptake was higher for symmetrically contacted membranes. The highest water uptake (0.15-0.17 wt %) was obtained for the plasticized PVC based Ca(2+)-selective membranes in DIW, whereas the water uptake was lower in 0.1 M electrolyte solutions. Symmetrically contacted Ca(2+)-selective SR membranes had much lower water uptake in 0.1 M CaCl(2) (0.03 wt %) than their plasticized PVC counterparts (0.1 wt %). However, the (noncontacted) SR membranes contained initially much more water (0.09-0.15 wt %) than the PVC membranes (0.04-0.07 wt %). Furthermore, in good accordance with the KF measurements, it was verified with FT-IR-attenuated total reflection (ATR) spectroscopy that the water content at the substrate/membrane interface and consequently in the whole membrane was influenced by the electrolyte solution.

The Coated-Wire Ion Selective Electrode (CWISE) of Chromate Using PVC-Membrane Based on Chitosan as A Carrier

A coated-wire ion selective electrode (CWISE) based on chitosan as a carrier for detection of chromate, was developed. CWISE has easy measurement for field analysis, good selectivity and sensitivity. The CWISE’s membrane consist of mixture an active material of chitosan, aliquat 336-chromate, polyvinylchloride (PVC) and dioctylphtalate (DOP) as plasticizer = 4:0.5:35:60.5 (% w/w) dissolved in tetrahydrofuran (THF) solvent (1:3 w/v). The electrode exhibited a good Nernstian slope of 29.77±0.03 mV/decade and a linear concentration range from 10 -6 to 10 -1 M for chromate. The limit of detection was 1.862 x 10 -6 M. It had response time of 20 – 40 sec, and could be used for 49 days. This chromate selective-electrode was found more selective towards the chromate ion than other anions, useable in pH range of 5.0 – 9.0 and temperature of 20 – 50 o C. It was applied as an electrode for direct determination of chromate in water samples and their result compared to standard spectrophotometric method.

Highly Selective Potentiometric Determination of Ag(I) Using 1,2,4,5-tetrakis(8-hydroxyquinolinoxymethyl)benzene Based Coated-Wire Ion-Selective Electrode

Highly Selective Potentiometric Determination of Ag(I) Using 1,2,4,5-tetrakis(8-hydroxyquinolinoxymethyl)benzene Based Coated-Wire Ion-Selective Electrode

Coated Wire PVC Membrane Sensor for Selective Determination of Copper Ion in Environmental Samples and Pharmaceutical Formulations

This work described the electrochemical response characteristic of poly (vinyl chloride) (PVC) membrane sensor and coated wire ion selective electrode (CWISE) based on the use of copper (II) salicylidene-N – anilinoacetohydrazone ionophore. o-nitrophenyloctylether (o-NPOE) is used as a plasticizer in the PVC matrix. The membrane sensors were prepared and the performance characteristics were evaluated according to IUPAC recommendations. The prepared sensors exhibited fast, stable and linear response for copper over a concentration range 1× 10× 6-1× 10× 2 M and 7× 10-5- 1× 10-2 M with cationic slopes of 29.6 and 27.1 mV per concentration decade at pH 5 for membranes doped with and without tetraphenylborate as an additive, respectively. The potentiometric selectivity data revealed minimal or no interference from common cations. Direct potentiometric determination of copper using the prepared membrane sensors gave average recoveries of 99.89 ± 0.9% and 100.04 ± 1.1% for membrane formulated with additive (detection limit; 1× 10-6-1× 10-2 M) and without additive (detection limit; 7× 10-5-1× 10-2 M), respectively. The sensors were used for measurement of copper content in industrial waste water; metal alloys containing from copper factories and pharmaceutical formulations. The developed method was found to be simple, accurate and precise when compared with conventional analytical methods for copper determinations (e.g; atomic absorption spectroscopy and voltammetry). Keywords: Salicylidene-N -anilinoacetohydrazone, Coated wire, Copper, Potentiometry, Waste water, Pharmaceutical formulations, Environmental Samples, Ion selective electrode, Spectrophotometry, Voltammetry, stripping potentiometry

Coated wire thorium ion selective electrode: Part I

Coated wire ion selective electrode for thorium ion selective potentiometry was developed. Thorium ion selective coated wire electrodes were prepared by depositing a membrane comprising of Aliquat-336 loaded with Th(NO3)62− ions and poly vinyl chloride in varying proportion. A linear near-Nernstian response with a slope of −29.5 ± 0.3 mV over thorium concentration range of 1 × 10−1–3 × 10−5 M in constant total nitrate concentration of 6 M was obtained for the electrodes of almost all the composition studied. In spite of small drift in response potential from composition to composition, day to day as well as from electrode to electrode, the slope of potential response line was constant within experimental error. Moreover, the electrode once prepared could be conveniently used over a period of one and half month.

Dual behavior of thiuram sulphide: Highly selective transport and ion-selective electrode for Ag(I) ions under two different conditions

Performance of tetraethylthiuram disulphide (TETDS) as a carrier of silver ion across a polymeric inclusion membrane has been studied. This compound is also used as an ionophore in coated-wire ion-selective electrode for silver ion determination. Fundamental parameters like ion carrier concentration in the membrane phase and thiosulphate concentration in strip phase were also studied to see their effect on the transport of silver ions. The efficiency of silver transport in the presence of some interfering ions was investigated. The coated-wire electrode gave a Nernstian behavior in the activity range 5 × 10 −6 to 1 × 10 −1 M. The ion-selective electrode exhibits high selectivity towards some alkali, alkaline earth and transition metal ions. The electrode was used as an indicator electrode in titrations of I −, Br − and Cl − with Ag + ion.

Coated wire ion selective electrodes for determination of cationic and anionic surfactants

In this paper two new coated wire ion selective electrodes are reported, one of which, prepared by aliquot permanganate as electroactive material, found to be useful for the determination of cationic surfactants. The other one, which was prepared using the ion-pair complex formed between cetyl trimethylammonium bromide (CTAB) and sodium dodecylsulfate (SDS) was found to be useful for the determination of anionic surfactants. Dip coating technique was used for the preparation of these electrodes. The characteristics of electrodes in terms of electrode response, response time, and working range of pH have been evaluated.

Potentiometric coated wire electrode for salicylate based on zinc(II) acetylacetonate

A coated-wire ion selective electrode based on zinc(II) acetylacetonate as ionophore exhibited linear response with Nernstian slope of -59.6 ± 1.0 mV/decade over a wide concentration range (1.0´10-5-1.0´10-1 mol L-1). This electrode has 5.0´10-6 mol L-1 detection limit. The proposed electrodes has a response time between 5-10 s to achieve a 95% steady potential for salicylate concentrations. The electrode was suitable for use in aqueous solutions in a wide pH range of 2.7 to 7.8. The electrode life time was tested over a period of two months to investigate its stability. No significant change in the performance of the electrode was observed during this period, but after two months, a gradual decrease ocurred in the slope. The proposed electrode showed high selectivity for salicylate over a number of common inorganic and organic anions. The electrode was successfully applied to the determination of salicylate in pharmaceutical samples.

Bis(2-hydroxyacetophenone)ethylenediimine as a Neutral Carrier in a Coated-Wire Membrane Electrode for Lead(II)

A coated-wire ion-selective electrode (CWISE), based on a Schiff base as a neutral carrier, was successfully developed for the detection of Pb(II) in aqueous solution. CWISE exhibited a linear response with a Nernstian slope of 29.4 +/- 0.5 mV/decade within the concentration range of 1.0 x 10(-5) - 1.0 x 10(-1) M lead ion. CWISE has shown detection limits of 5.0 x 10(-6) M. The electrode exhibited good selectivity over a number of alkali, alkaline earth, transition and heavy metal ions. This sensor yielded a steady potential within 10 to 20 s at a linear dynamic range. The electrode was suitable for use in aqueous solutions in a pH range of 2.0 to 5.0. Applications of this electrode for the determination of lead in real samples and as indicator electrode for potentiometric titration of Pb2+ ion using K2CrO4 are reported.

Potentiometric Flow Injection Analysis of Bromhexine Hydrochloride and its Pharmaceutical Preparation Using Conventional and Coated Wire Ion-Selective Electrodes

Bromhexine hydrochloride ion-selective electrodes (conventional type) based on bromhexinium tetraphenyl borate (I) and bromhexinium-phosphotungstate (II) were prepared. The electrodes exhibited mean slopes of calibration graphs of 59.4 mV and 59.8 mV per decade of bromhexine concentration at 25°C for electrode (I) and (II), respectively. Both electrodes could be used within the concentration range 3.16x10-5-1.00x10-2 M bromhexine within the pH range 2.0-4.5. The standard electrodes potentials were determined at different temperatures and used to calculate the isothermal coefficients of the electrodes, which were 0.00065 and 0.00050 V°C-1 for (I) and (II), respectively. The electrodes showed a very good selectivity for bromhexine with respect to a number of inorganic cations, amino acids and sugars. The electrodes were applied to the potentiometric determination of bromhexine hydrochloride and its pharmaceutical preparation under batch and flow injection conditions. Graphite, copper and silver coated wires were prepared, characterized and successfully applied as sensors for the drug under investigation.

Lead ion-selective electrode prepared by sol–gel and PVC membrane techniques

Sol–gel electrode and coated-wire ion-selective electrode (CWISE) based on Schiff base as a neutral carrier, was successfully developed for detection of Pb(II) in aqueous solution. The sol–gel and CWISE exhibited linear response with Nernstian slope of 29.1 and 28.9 mV/decade, respectively, within the concentration ranges of 5.0 × 10 −6 to 1.0 × 10 −1 mol L −1 lead ion for sol–gel and coated. The sol–gel and CWISE has shown detection limits of 3.0 × 10 −6 and 5.0 × 10 −6 M, respectively. The electrodes exhibited good selectivities over a number of alkali, alkaline earth, transition and heavy metal ions. Those sensors yielded steady potential within 10–20 s at linear dynamic range. The electrodes are suitable for use in aqueous solutions in a wide pH range of 4.0–8.2. Applications of those electrodes for determination of lead in real samples and as indicator electrode for potentiometric titration of Pb 2+ ion using K 2CrO 4 are reported.

Coated-wire iron(III) ion-selective electrode based on iron complex of 1,4,8,11-tetraazacyclotetradecane

The work described here comprises the determination of Fe(III) by ion selective potentiometry using a coated-wire ion-selective electrode (CWISE) based on iron–cyclam complex. Linear Nernstian response for this electrode was obtained over the total Fe(III) concentration range of 1 × 10 −2 to 1 × 10 −6 M in 0.05 M HNO 3, H 2SO 4, HClO 4, HCl, KNO 3 and KCl media, with a slope of 60 ± 5 mV per decade change. Working pH range of the electrode was found to be 1.3–3.5. Selectivity coefficients of some mono- and divalent metal ions were determined. Analysis of alloys, electroplating bath solutions and pharmaceutical samples have been carried out using this CWISE and the results are found to be comparable with those obtained by using conventional methods.

Coated wire chromium(III) ion-selective electrode based on azamacrocycles.

Tetraazacyclotetradecane, tetratosyltetraaza 12C4, and tritosyltriaza 9C3 have been explored as electroactive materials for preparing coated wire ion-selective electrodes (CWISEs) for Cr(III) ions. The best performance was observed for the membrane comprising electroactive material (tetratosyltetraaza 12C4), plasticizer (dibutyl phthalate), and poly(vinyl chloride) in the optimum ratio 5:60:35 (w/w). Linear Nernstian response for this electrode was obtained over the total Cr(III) concentration range of 1 x 10(-1) to 1 x 10(-7) M in 0.05 M NH4NO3 medium, with a slope of 20 +/- 1 mV per decade change. The working pH range of the electrode was 1.8-5.5. Selectivity coefficients of some mono, divalent, and trivalent metal ions were determined. Analyses of electroplating bath solutions, chromating, and effluent samples have been carried out using this CWISE and the results are found to be comparable with those obtained by using conventional methods or by AAS.

Stability Constants of Some Macrocyclic Complexes of Ag(I) and Cu(II) in Mixed Solvents by Potentiometry

Stability constants of complexes of Ag(I) and Cu(II) perchlorates and nitrates with some macrocyclic compounds in 90 and 75% (v/v) DMSO+water and 75% (v/v) DMF+water media have been determined by potentiometry. Silver and copper wires, and Coated Wire Ion Selective Electrodes (CWISE) were used as indicator electrodes. It was observed that complexation is stronger when the salt is present as a perchlorate than when it is as a nitrate. For both cations the stability constant values in 75% (v/v) DMF+water were somewhat higher than in 75% (v/v) DMSO. The macrocyclic effect due to cyclization of linear amine tosylates has been observed. Competitive potentiometry has been utilized to compare some of the results.

Coated wire ion-selective electrode for palladium(II) and its application to catalyst analysis

The construction, performance and application of polymeric membrane (PME) and coated wire (CWE) palladium(II)-selective electrodes based on the ion pair between tetra bromopalladate(II) and hexadecylpyridinium cation (HDP +) in a poly(vinyl chloride) matrix, plasticized with o-NPOE are described. The influence of membrane composition, bromide ion concentration and pH on the potentiometric responses of electrodes were investigated. Nernstian responses were obtained for the two type of electrodes with low limits of detection (1.0×10 −6 M for PME and 5.0×10 −8 M for CWE). The potentiometric responses are independent of the pH of test solution in the range 3–8. The response time of electrodes are fast (30 s for PME and 10 s for CWE), and they can be used for at least 3 months without any considerable divergence in potentials. The proposed electrodes revealed good selectivity for palladium(II) respect to different cations and anions. They were used to the direct potentiometric determination of palladium(II) in silicon-alumina catalysts.

Coated-Wire and Coated-Disc Cu(II) Ion-Selective Electrodes Based on Cu(II) Complex with Cyclized Salophen

Coated-wire and coated-disc ion selective electrodes (ISE) based on cyclized N,N ′-bis(salicylidene)-o-phenylenediamine (salophen) complex with Cu(II) were fabricated for determination of Cu(II) in aqueous solutions. The response of the ISE was optimized by variation of membrane composition and evaluation of the various experimental conditions. Near Nernstian slopes (˜28 mV/decade) were obtained. The linear range of the ISE ranged from 5 × 10−5 to 1 × 10−2 M Cu(II).The potentiometric selectivity coefficients (K ij ) were determined for , Ca2+, Mg2+, Ni2+, Pb2+, Zn2+, Cd2+, Co2+, Fe3+, Hg2+, , CH3COO−, Br−, I−, , and SCN−. The selectivity coefficients were in the range from 10−2 to 10−3 for all ions tested except Hg2+, I−, and to less extent Fe3+. The fabricated ISE using the Cu(II)-salophen complex are reliable and stable.