Coated wire silver-ion selective electrode based on a N,N'-bis(2-thienylmethylene)-1,2-diaminobenzene.

A novel membrane coated platinum-wire electrode (MCPWE) based on N,N'-bis(2-thienylmethylene)-1,2-diaminobenzene (BTMD) for highly selective determination of Ag+ ion has been developed. The influences of membrane composition and pH on the potentiometric responses of electrode were investigated. The potentiometric responses are independent of the pH of the test solution in the range of 5.0 - 9.0. The electrode shows a linear response for Ag+ ion over the concentration range of 1.0 x 10(-60 to 1.0 x 10(-1) M with a lower detection limit of 6.0 x 10(-7) M. The electrode possesses a Nernstian slope of 59.7 mV decade(-1) and a fast response time of < or = 17 s and can be used for at least 2 months without any observable deviation. The proposed electrode displayed very good selectivity for Ag+ ion with respect to NH4+ and alkali, alkaline earth and some common transition metal ions. The practical utility of the electrode has been demonstrated by its use as the indicator electrode in the potentiometric titration of an AgNO3 solution with a NaI solution and in determination of the silver content of a developed radiological film.     

Mercury(II) ion-selective electrodes based on p-tert-butyl calix[4]crowns with imine units.

A PVC membrane incorporating p-tert-butyl calix[4]crown with imine units as an ionophore was prepared and used in an ion-selective electrode for the determination of mercury(II) ions. An electrode based on this ionophore showed a good potentiometric response for mercury(II) ions over a wide concentration range of 5.0 x 10(-5) - 1.0 x 10(-1) M with a near-Nernstian slope of 27.3 mV per decade. The detection limit of the electrode was 2.24 x 10(-5) M and the electrode worked well in the pH range of 1.3 - 4.0. The electrode showed a short response time of less than 20 s. The electrode also showed better selectivity for mercury(II) ions over many of the alkali (Na+, -1.69; K+, -1.54), alkaline-earth (Ca2+, -3.30; Ba2+, -3.32), and heavy metal ions (Co2+, -3.67; Ni2+, -3.43; Pb2+, -3.31; Fe3+, -1.82). Ag+ ion was found to be the strongest interfering ion. Also, sharp end points were obtained when the sensor was used as an indicator electrode for the potentiometric titration of mercury(II) ions with iodide and dichromate ions.     

Ketoconazol‐Triiodide Ion Pair Complex as a Suitable Carrier in an Iodide Selective Membrane Electrode

A novel membrane sensor for selective monitoring of iodide, consisting of a triiodide‐ketoconazole ion pair complex dispersed in a PVC matrix, plasticized with a mixture of 2‐nitrophenyl octyl ether and dioctylphtalate with unique selectivity toward iodide ions, is described. The influence of membrane composition, pH of test solution and foreign ions on the electrode performance were investigated. The optimized membrane demonstrates a near‐Nernstian response for iodide ions over a wide linear range from 1.0 × 10^?2 to 1.0 × 10^?5 M, at 25 ± 1 °C. The electrode could be used over a wide pH range 3–10 and has the advantages of high selectivity, fast response time and good lifetime (over 4 months). It was successfully used as indicator electrode in potentiometric titrations and direct potentiometric assay of iodide ions.     

Highly selective iodide membrane electrode based on a cerium salen.

A highly selective PVC membrane electrode based on a cerium-salen complex was prepared. The sensor displays an anti-Hofmeister selectivity sequence with a preference for iodide ion over many common organic and inorganic anions. The proposed electrode exhibits a near-Nernstian behavior over a wide concentration range (5.0 x 10(-2) - 8.0 x 10(-6) M) with a slope of 57.5 mV per decade, and a detection limit of 6.0 x 10(-6) M. The electrode has a very fast response time and can be used in the pH range of 3.0 - 1 1.0. It was applied, as an indicator electrode, in potentiometric titration of Ag+ ions.     

Bis-dimethylaminobenzaldehyde Schiff-base cobalt(II) complex as a neutral carrier for a highly selective iodide electrode.

A new solvent polymeric membrane electrode based on N,N'-bis-(dimethylaminobenzaldehyde)-glycine cobalt(II) [Co(II)-BDMABG] as a neutral carrier is described, which displays a preferential potentiometric response to iodide ion and an anti-Hofmeister selectivity sequence in the following order: I- > ClO4- > Sal- > SCN- > NO2- > Br- > NO3- > Cl- > SO3(2-) > SO4(2-). The electrode exhibits a near-Nernstian potential linear range of 9.0 x 10(-7)-1.0 x 10(-1) M with a detection limit of 6.8 x 10(-7) M and a slope of -53.0 mV/decade in pH 2.0 of a phosphate buffer solution at 20 degrees C. The response mechanism is discussed in view of the A.C. impedance technique and the UV spectroscopy technique. The electrode was successfully applied to the determination of iodide in Jialing River and Spring in Jinyun Mountains with satisfactory results.     

Silver(I)-selective coated-wire electrode based on an octahydroxycalix[4]arene derivative.

The performance of octahydroxycalix[4]arene derivative used as a neutral carrier for silver polymeric membrane electrode was studied. The sensor gave a good Nernstian response of 58 +/- 1 mV per decade for silver ion in the activity range 3.3 x 10(-6) to 3.3 x 10(-2) M Ag+. The limit of detection reached 2.1 x 10(-6) M Ag+ and exhibited high selectivity for silver ion against the alkali, alkaline earth and transition metal ions. The sensor can be used in wide pH range from 1.5 to 6.5. The response time of the sensor is less than 20 s. The potentiometric sensor was used as the indicator electrode in the titration of Ag+ ions by sodium chloride solution.     

Aluminium(III)-selective electrode based on a newly synthesized tetradentate Schiff base

A PVC membrane electrode for aluminium ion based on bis(5-phenyl azo salicylaldehyde) 2,3-naphthalene diimine (5PHAZOSALNPHN) as an ion carrier was developed. The electrode exhibits a Nernstian slope of 19.3+/-0.8 mV per decade and a linear range of 5.0x10(-6)-1.0x10(-2) M for Al(NO(3))(3). The limit of detection is 2.5x10(-6) M. It has a fast response time of about 10 s and can be used for at least 10 weeks without observing any deviation. The proposed membrane sensor revealed good selectivity for Al(3+) over a wide variety of other metal ions and could be used in pH range of 2.9-5.0. It was used as an indicator electrode in potentiometric titration of aluminium ion.     

A mercury(II) ion-selective electrode based on N,N-dimethylformamide-salicylacylhydrazone as a neutral carrier.

A new PVC membrane mercury(II) ion electrode based on N,N-dimethylformamide-salicylacylhydrazone (DMFAS) as an ionophore is described, which shows excellent potentiometric response characteristics and displays a linear log[Hg(2+)] versus EMF response over a wide concentration range between 6.2 x 10(-7) and 8.0 x 10(-2) M with a Nerstian slope of 29.6 mV per decade and a detection limit of 5.0 x 10(-7) M. The response time for the electrode is less than 30 s and the electrode can be used for more than 2 months with less than a 2 mV observed divergence in a potentials. The proposed electrode exhibits very good selectivity for mercury(II) ions over many cations in a wide pH range (pH 1 - 4). The electrode was also applied to the determination of a mercury(II) ion in vegetables and in Azolla filiculoides.     

Synthesis of N'-(1-pyridin-2-ylmethylene)-2-furohydrazide and its application in construction of a highly selective PVC-based membrane sensor for La(III) ions.

A highly La(III) ion-selective PVC membrane sensor based on N'-(1-pyridin-2-ylmethylene)-2-furohydrazide (NPYFH) as an excellent sensing material was successfully developed. The electrode shows a good selectivity for La(III) ion with respect to most common cations including alkali, alkaline earth, transition and heavy metal ions. The proposed sensor exhibits a wide linear response with slope of 19.2 +/- 0.6 mV per decade over the concentration range of 1.0 x 10(-6) - 1.0 x 10(-1) M, and a detection limit of 7.0 x 10(-7) M of La(III) ions. The sensor response is independent of pH in the range of 3.5-10.0. The proposed electrode was applied as an indicator electrode in potentiometric titration of La(III) ion with EDTA.     

Copper (II) ion selective liquid membrane electrode based on new Schiff base carrier

Cu2+ selective PVC membrane electrode based on new Schiff base 2, 2'-[1,9 nonanediyl bis (nitriloethylidyne)]-bis-(1-naphthol) as a selective carrier was constructed. The electrode exhibited a linear potential response within the activity range of 1.0 x 10(-6) - 5.0 x 10(-3) moll(-1) with a Nernstian slope of 29 +/- 1 mV decade(-1) of Cu2+ activity and a limit of detection 8.0 x 10(-7) mol l(-1). The response time of the electrode was fast, 10 s, and stable potentials were obtained within the pH range of 3.5- 6.5. The potentiometric selectivity coefficients were evaluated using two solution method and revealed no important interferences except for Ag+ ion. The proposed electrode was applied as an indicator electrode to potentiometric titration of Cu2+ ions and determination of Cu2+ content in real samples such as black tea leaves and multivitamin capsule.     

Silver(I) ion-selective membrane based on Schiff base-p-tert-butylcalix[4]arene

A PVC membrane electrode for silver(I) ion based on Schiff base-p-tert-butylcalix[4]arene is reported. The electrode works well over a wide range of concentration (1.0 x 10(-5)-1.0 x 10(-1) mol dm-3) with a Nernstian slope of 59.7 mV per decade. The electrode shows a fast response time of 20 s and operates in the pH range 1.0-5.6. The sensor can be used for more than 6 months without any divergence in the potential. The selectivity of the electrode was studied and it was found that the electrode exhibits good selectivity for silver ion over some alkali, alkaline earth and transition metal ions. The silver ion-selective electrode was used as an indicator electrode for the potentiometric titration of silver ion in solution using a standard solution of sodium chloride; a sharp potential change occurs at the end-point. The applicability of the sensor to silver(I) ion measurement in water samples spiked with silver nitrate is illustrated.     

Highly selective PVC-membrane electrodes based on Co(II)-Salen for determination of nitrite ion.

A cobalt(II) derivative was used as a suitable ionophore for the preparation of a polymeric membrane nitrite-selective electrode. The electrode reveals a Nemstian behavior over a very wide NO2- ion concentration range (1.0 x 10(-6)-1.0 x 10(-1) M) and a very low detection limit (5.0 x 10(-7) M). The potentiometric response is independent of the pH of solution in the pH range 4.0-9.5. The electrode shows advantages such as low resistance, fast response and, most importantly, good selectivity relative to a wide variety of inorganic and organic anions. In fact, the selectivity behavior of the proposed NO2- ion-selective electrode shows great improvements compared to the previously reported electrodes for nitrite ion. The proposed electrodes could be used for at least 2 months without any significant changes in potentials. The electrode was successfully applied to the determination of nitrate ion concentrations in sausage and milk samples.     

Chemically modified carbon paste electrode for iodide determination on the basis of cetyltrimethylammonium iodide ion-pair.

A new carbon paste electrode (CPE) for the determination of iodide ion based on a cetyltrimethylammonium iodide (CTMAI) ion pair as an electroactive material is described. The electrode shows a linear response for iodide ion over the concentration range of 4 x 10(-5) M to 1 x 10(-1) M with a lower detection limit of 4 x 10(-5) M at 25 degrees C. The electrode has a Nemstian slope of -55.0 +/- 0.4 mV/decade and a fast potential response of 45 s, which is almost constant over a pH range of 5.0 - 9.0. Selectivity coefficient data of the CTMAI-CPE for some common ions show negligible interference, and the electrode has high selectivity towards the iodide ion. An average recovery of 101.83% with a relative standard deviation of 1.53% has been achieved for the determination of iodide in Flaxedil (gallamine triethiodide) ampoules, a muscle relaxant drug. The electrode has been examined for the determination of iodide in saline water; the results were found to compare favorably with those obtained using Metrohm iodide ISE. The electrode has been utilized as an end-point indicator electrode for the determination of Hg(II) and phenylmercury(I) in their aqueous solutions using potentiometric titration with a potassium iodide standard solution.     

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.     

Hydrogen ion-selective poly(vinyl chloride) membrane electrode based on a calix[4]arene.

A hydrogen ion-selective poly(vinyl chloride) membrane electrode was constructed using 5,11,17,23-tetra-tert-butyl-25,26,27,28-tetracyanomethoxycalix[4]arene as a neutral carrier. The electrode showed an apparent Nernstian response in the 2-11.5 pH range with a slope of 54.0 +/- 0.2 mV/pH at 20 +/- degrees C. This electrode showed a rapid response of the emf to changes in the pH, high ion selectivity with respect to lithium, sodium and potassium, and characteristics similar to those reported for the conventional pH glass membrane electrode. It can be used as a potentiometric indicator electrode in hydrofluoric acid solutions. The effects of iodide, thiocyanate, perchlorate and bromide on the characteristics of the electrode were also considered.     

Lead(II)-selective electrode based on phenyl disulfide.

A PVC membrane electrode for lead ions based on phenyl disulfide as the membrane carrier was developed. The electrode exhibits a good Nernstian slope of 29.3 +/- 0.7 mV/decade and a linear range of 2.0 x 10(-6)-1.0 x 10(-2) M for Pb(NO3)2. The limit of detection is 1.2 x 10(-6) M. It has a response time of 45 s and can be used for at least fifty days without any divergence in potential. The proposed membrane sensor revealed high selectivity for Pb2+ over a wide variety of other metal ions and could be used in the pH range of 3.5-6.3. The electrode was used as an indicator electrode in potentiometric titration of lead ions.     

Charge-transfer triiodide ion-selective electrode based on 7,16-dibenzyl-1,4,10,13-tetraoxa-7,16-diazacyclooctadecane.

A new PVC membrane electrode for the triiodide ion based on a charge-transfer complex of iodine with 7,16-dibenzyl-1,4,10,13-tetraoxa-7,16-diazacyclooctadecane as a membrane carrier was prepared. The electrode exhibits a Nernstian response for triiodide ions over a wide concentration range (1.0 x 10(-1)-1.0 x 10(-5) M) with a slope of 59.3 +/- 0.9 mV decade(-1) and a detection limit of 6.3 x 10(-6) M. It has a response time of 30 s and can be used for at least 3 months without any divergence in the potential. The potentiometric response is independent of the pH, in the pH range 1.6 - 10.0. The proposed electrode has shown very high selectivity for the triiodide ion over a wide variety of other anions. This electrode was successfully applied as an indicator electrode in the potentiometric titration of ascorbic acid and hydroquinone from pharmaceutical preparations as well as ascorbic acid in orange juice and dissolved O2 in tap water.     

Anion selective polymeric membrane electrodes based on cyclopalladated amine complexes

The potentiometric anion selectivity of two polymer membrane based electrodes (I and II) formulated with two new cyclopalladated amine complexes as the active components are examined. The electrodes exhibit a non-Hofmeister selectivity pattern with a significantly enhanced response towards thiocyanate, iodide and nitrite. The graph potential versus log c is linear over the concentration range 10(-6)-6x10(-2) M thiocyanate with electrode I and 10(-6)-10(-3) M with electrode II; 10(-5)-10(-2) M iodide with electrode I and 10(-3)-6x10(-2) M with electrode II; and 10(-3)-6x10(-2) M nitrite with both electrodes. The influence of the plasticizer and pH are studied. The potentiometric selectivity coefficients for I, II and blank membrane electrodes are reported. The selective interaction between Pd(II) thiocyanate, iodide and nitrite is postulated to be the reason for its higher response.     

Organic-inorganic composite cation-exchanger: poly-o-toluidine Zr(IV) phosphate-based ion-selective membrane electrode for the potentiometric determination of mercury

A new heterogeneous precipitate of an organic-inorganic composite cation-exchanger poly-o-toluidine Zr(IV) phosphate was utilized for the preparation of a Hg(II) ion-sensitive membrane electrode for the determination of Hg(II) ions in real aqueous as well as in real samples. The electrode showed good potentiometric response characteristics, and displayed a linear log[Hg(2+)] versus EMF response over a wide concentration range of 1 x 10(-1) - 1 x 10(-6) M with a Nernstian slope of 30 mV per decade change in concentration with a detection limit of 1 x 10(-6). The membrane electrode showed a very fast response time of 5 s and could be operated well in the pH range 2 - 8. The selectivity coefficients were determined by the mixed-solution method, and revealed that the electrode was selective in the presence of interfering cations; however most of these did not show significant interference in the concentration range of 1 x 10(-1) - 1 x 10(-4) M. The lifetime of the membrane electrode was observed to be 120 days. The analytical utility of this electrode was established by employing it as an indicator electrode in the potentiometric titrations of Hg(2+) ions from a synthetic mixture as well as drain water.     

Novel sulfate ion-selective polymeric membrane electrode based on a derivative of pyrilium perchlorate

A sulfate ion-selective PVC membrane sensor based on 4-(4-bromophenyl)-2,6-diphenylpyrilium perchlorate (BDPP) as a novel sensing material is successfully developed. The electrode shows a good selectivity for sulfate ion with respect to common organic and inorganic anions. The sensor exhibits a good linear response with slope of -28.9+/-0.5 mV per decade over the concentration range of 1.0x10(-6)-1.0x10(-2) M, and a detection limit of 8.0x10(-7) M of SO(4)(2-) ions. The electrode response is independent of pH in the range of 4.0-9.0. The proposed sensor was applied as an indicator electrode in potentiometric titration of sulfate and barium ions, and to the determination of zinc in zinc sulfate tablets.