Copper(II)-selective membrane electrodes based on some recently synthesized mixed aza-thioether crowns containing a 1,10-phenanthroline sub-unit

Three different mixed aza-thioether crowns containing a 1,10-phenanthroline sub-unit were investigated to characterize their abilities as copper(II) ion carriers in PVC-membrane electrodes. The electrode based on L1 exhibited a Nernstian response for Cu²⁺ ions over a wide concentration range (2×10⁻¹ to 1×10⁻⁵ M) with a limit of detection of 8.0×10⁻⁶ M (0.5 p.p.m.). The response time of sensor is 15 s, and the membrane can be used for more than 3 months without observing any deviation. The electrode revealed comparatively good selectivities with respect to many alkali, alkaline earth, transition and heavy metal ions, and could be used in a pH range of 2.5–5.5. It was applied to the direct determination and potentiometric titration of the copper(II) ion.     

A selective membrane electrode for iodide ion based on a thiopyrilium ion derivative as a new ionophore

A highly selective electrode for iodide ion based on a thiopyrilium derivative as an excellent ionophore is described. At pH 5.5-8.0, the electrode responds to iodide ion in a linear range from 1.0×10⁻¹ to 8.0×10⁻⁷ M with a slope of 60.2 mV per decade, and a detection limit of 2.0×10⁻⁷ M. Selectivity coefficients determined with the match potential method (MPM) indicate that the interference from inorganic and organic anions is very small. The proposed sensor shows a fast response time of approximately 15 s. It was applied as an indicator electrode in titration of iodide with Ag⁺.     

Gliclazide as novel carrier in construction of PVC-based La(III)-selective membrane sensor

A PVC-based sensor for La³⁺ ions based on N-[hexahydrocyclopentapyrol-2((1H)yl)amino]carbonyl]-4-methyl benzene sulfonamide (gliclazide) as a novel carrier was prepared. The electrode exhibits a Nernstian response for La³⁺ over a wide concentration range (1.0×10⁻¹-1.0×10⁻⁶ M) with a slope of 20.1 mV per decade. The limit of detection is 8.0×10⁻⁷ M. The sensor has a very short response time (<15 s) and a useful working pH range of 4.0-8.0. The proposed membrane sensor shows excellent discriminating ability towards La³⁺ ions with regard to several alkali, alkaline earth, transition and heavy metal ions. The electrode was successfully applied for determination of La³⁺ in binary mixtures.     

Nickel(II) selective membrane potentiometric sensor using a recently synthesized mercapto compound as neutral carrier

A PVC membrane electrode for Ni²⁺ ions based on a recently synthesized mercapto compound, as an ionophore was prepared. The electrode exhibits a Nernstian slope of 28-30 mV per concentration decade at wide concentration range of (1.0×10⁻²-1.0×10⁻⁷ M). It has a fast response time of <15 s and can be used for at least 4 weeks. The potentiometric response is independent of the pH of the test solution in the pH range 5-8.5. The proposed electrode revealed good selectivities over a wide variety of other cations including alkali, alkaline earth, transition and heavy metal ions. It was successfully applied to the direct determination and potentiometric titration of nickel ion with EDTA.     

A novel Mn PVC membrane electrode based on a recently synthesized Schiff base

A new PVC membrane electrode for manganese(II) ion based on a recently synthesized Schiff base of 5-[(4-nitrophenylazo)-N-hexylamine]salicylaldimine is reported. The electrode exhibits a Nernstian response for Mn²⁺ ions over a wide concentration range (4.0 × 10⁻⁷ to 1.8 × 10⁻² mol L⁻¹) with a slope of 30.1 (±1.0). The limit of detection is 1.0 × 10⁻⁷ mol L⁻¹. The electrode has a fast response time (∼10 s), a satisfactory reproducibility and relatively long life time. The proposed sensor revealed good selectivities over a wide variety of other cations include hard and soft metals. This electrode could be used in a pH range of 4.5-7.5. It was used as an indicator electrode in potentiometric titration of manganese(II) ions with EDTA solution.     

Terbium(III) Ion-Selective Electrochemical Sensor Based on Hematoporphyrin

Abstract

A polyvinyl chloride (PVC) based membrane sensor for terbium ions was prepared by employing Hematoporphyrin (HP) as an ionophore. The sensor revealed a very good selectivity (expect for the Fe³⁺ion) with respect to common alkali, alkaline earth and heavy metal ions. The plasticized membrane electrode exhibits a Nernstian response for Tb³⁺ ions over a wide concentration range (1.0 × 10^?6 ? 1.0 × 10^?2 M) with a slope of 19.8±0.3 mV per decade and low detection limit of 7.4 × 10^?7 M. The developed sensor was used in determination of F^? in mouth wash preparation sample.     

Strontium(II)-selective electrode based on a macrocyclic tetraamide

A new PVC membrane electrode based on 5,7,12,14-dibenzo-2,3,9,10-tetraoxa-1,4,8,11-tetraazacyclotetradecane (I) as an ion carrier, o-nitrophenyloctyl ether (o-NPOE) as solvent mediator and sodium tetraphenylborate (NaTPB) as lipophilic additive was fabricated and investigated as Sr²⁺-selective electrode. The best performance was exhibited by the membrane having composition 8:200:4:120 (I:o-NPOE:NaTPB:PVC). The electrode exhibited a Nernstian response for strontium ion over a wide concentration range 3.98 × 10⁻⁶ to 1.0 × 10⁻¹ M with a slope of 29.0 ± 0.1 mV/decade of concentration and a detection limit of 2.82 × 10⁻⁶ M. It showed a response time of less than 10 s and could be used for at least 3 months without any divergence in potential. The proposed electrode showed a good discriminating ability towards strontium(II) ion over a wide variety of other metal ions including alkali, alkaline earth, transition, and heavy metal ions. The electrode can be used in the pH range of 2.5-10.5 and in mixtures containing up to 35% (v/v) non-aqueous content. It was used as an indicator electrode in potentiometric titration of strontium ion against EDTA.     

Lead ion-selective membrane electrodes based on some recently synthesized 9,10-anthraquinone derivatives

Four different 9,10-anthraquinone derivatives were studied to characterize their abilities as lead ion carrier in PVC membrane electrodes. The electrode based on 1,8-dihydroxy-2,7-bis(prop-2′-enyl)-9,10-anthraquinone exhibits a Nernstian response for Pb²⁺ ions over a wide concentration range (2.0×10⁻³–2.0×10⁻⁶ M). The response time of the sensor is 30 s and the membrane can be used for more than four months without observing any deviation. The electrode revealed comparatively good selectivities with respect to alkali, alkaline earth and some transition and heavy metal ions. It was used as an indicator electrode in potentiometric titration of sulfate ions with a lead ion solution.     

Tetrachloroferrate(III)-selective liquid membrane electrode based on crystal violet

An extract of crystal violet-tetrachloroferrate(III) in nitrobenzene was used to prepare a tetrachloroferrate(III)-selective liquid membrane electrode with a poly(vinyl chloride) support. The optimal conditions to determine 2.5 × 10^–5 – 5.0 × 10^–2 M iron(III) as tetrachloroferrate(III) (anionic slope 56 mV/decade, detection limit 7.9 × 10^–6 M) were found to be 4.0–5.5.M total chloride in 0.75–1.5M hydrochloric acid. The electrode was reliably applied to determine iron in human blood, haematite and mineralized vitamin syrup by direct potentiometry, standard and sample additions as well as standard subtraction techniques.     

Strontium(II) selective PVC membrane electrode based acetophenone semicarbazone (ACS) as an ionophore

A new PVC membrane based strontium(II) ion-selective electrode has been constructed using acetophenone semicarbazone as a neutral carrier. The sensor exhibits a Nerstian response for strontium(II) ion over a wide concentration range 1.0 × 10⁻²–1.0 × 10⁻⁷ M with the slope of 29.4 mV/per decade. The limit of detection was 2.7 × 10⁻⁸ M. It was relatively fast response time (<10 s for concentration ⩾1.0 × 10⁻³ and <15 s for concentration of ⩾1.0 × 10⁻⁶ M) and can be used for 8 months without any considerable divergence in potentials. The proposed sensor revealed relatively good selectivity and high sensitivity for strontium(II) over a mono, di, trivalent cation and can be used in a pH range of 2.5–10.5. It was also successfully used as an indicator electrode in potentiometer titration and in the analysis of concentration in various real samples.     

A highly selective thallium(I) electrode based on a thia substituted macrocyclic ionophore

A new highly Tl(I)-selective PVC membrane electrode based on tetrathia macrocycle 6,7: 14,15-dibenzo-5,8,13,16-tetraoxo-1,4,9,12-tetrathiacyclohexadecane [Bz₂O₄(16)aneS₄] (I) as membrane carrier, o-nitrophenyloctyl ether (o-NPOE) as solvent mediator and potassium tetrakis(p-chlorophenyl)borate (KTpClPB) as lipophilic additive has been developed. The best performance was given by the membrane of macrocycle (I) with composition 3:120:1.5:50 (I:o-NPOE:KTpClPB:PVC). This electrode exhibits a Nernstian response to Tl(I) ions in the concentration range 1.0 × 10⁻¹-2.23 × 10⁻⁶ M with a slope of 58.2 mV/decade of concentration and a detection limit of 1.58 × 10⁻⁶ M. The response time of the sensor is 12 s and can be used over a period of 4 months with good reproducibility. The proposed electrode revealed good selectivity over a wide variety of other cations including alkali, alkaline earth, heavy and transition metals. The electrode works well over a pH range of 3.2-11.5 and in partially non-aqueous medium with up to 30% organic content. The sensor was also used as an indicator electrode in potentiometric titration of Tl(I) ions with KI solution.     

Highly selective thiocyanate membrane electrode based on butane-2,3-dione bis(salicylhydrazonato)zinc(II) complex

A highly selective poly(vinyl chloride) (PVC) membrane electrode based on butane -2,3-dione bis(salicylhydrazonato) zinc(II) [Zn (BDSH)] complex as carrier for thiocyanate-selective electrode is reported. The influence of membrane composition, pH and possible interfering anions were investigated on the response properties of the electrode. The sensor responds to thiocyanate in linear range from 1.0 × 10⁻⁶ to 1.0 × 10⁻¹ M with a slope −56.5 ± 1.1 mV decade⁻¹, over a wide pH range of 3.5-8.5. The limit of detection of the electrode was 7.0 × 10⁻⁷ M SCN⁻. Selectivity coefficients determined with fixed interference method (FIM) indicate a good discriminating ability towards SCN⁻ ion in comparison to other anions. The proposed sensor has a fast response time of about 5-15 s and can be used for at least 3 months without any considerable divergence in potential. It was applied as indicator electrode in titration of thiocyanate with Ag⁺ and in potentiometric determination of thiocyanate in saliva and urine samples.     

Mercury(II) ion-selective polymeric membrane sensor based on a recently synthesized Schiff base

A new polyvinyl chloride (PVC) membrane electrode that is highly selective to Hg(II) ions was prepared by using bis[5-((4-nitrophenyl)azo salicylaldehyde)] (BNAS) as a suitable neutral carrier. The sensor exhibits a Nernstian response for mercury ions over a wide concentration range (5.0×10⁻²-7.0×10⁻⁷ M) with a slope of 30±1 mV per decade. It has a response time of <10 s and can be used for at least 3 months without any measurable divergence in potential. The electrode can be used in the pH range from 1.0 to 3.5. The proposed sensor shows fairly good discriminating ability towards Hg²⁺ ion in comparison with some hard and soft metals. The electrode was used in the direct determination of Hg²⁺ in aqueous solution and as an indicator electrode in potentiometric titration of mercury ions.     

A bromide selective polymeric membrane electrode based on Zn(II) macrocyclic complex

A novel bromide ion-selective PVC membrane sensor based on 2,3,10,11-tetraphenyl-1,4,9,12-tetraazacyclohexadeca-1,3,9,11-tetraene zinc(II)complex (I) as carrier has been developed. The electrode exhibited wide working concentration range 2.2 × 10⁻⁶ to 1.0 × 10⁻¹ M and a limit of detection as 1.4 × 10⁻⁶ M with a Nernstian slope of 59.2 ± 0.5 mV per decade. The response time of electrode was 20 s over entire concentration range. The electrode possesses the advantages of low resistance, fast response and good selectivities for bromide over a variety of other anions and could be used in a pH range of 3.5–9.5. It was successfully used as an indicator electrode in the potentiometric titration of bromide ions with silver ion and also in the determination of bromide in real samples.     

Highly selective and sensitive copper membrane electrode based on a new synthesized Schiff base

Bis(2-hydroxyacetophenone)butane-2,3-dihydrazone (BHAB) was used as new N-N Schiffs base which plays the role of an excellent ion carrier in the construction of a Cu(II) membrane sensor. The best performance was obtained with a membrane composition of 30% poly(vinyl chloride), 55% o-nitrophenyloctyl ether (NPOE), 7% BHAB and 8% oleic acid (OA). This sensor shows very good selectivity and sensitivity towards copper ion over a wide variety of cations, including alkali, alkaline earth, transition and heavy metal ions. The effect of membrane composition and pH and influence of additive anionic on the response properties of electrode were investigated. The electrode exhibits a Nernstian behavior (with slope of 29.6 mV per decade) over a very wide concentration range (5.0 × 10⁻⁸ to 1.0 × 10⁻² mol L⁻¹) with a detection limit of 3.0 × 10⁻⁸ mol L⁻¹ (2.56 ng mL⁻¹). It shows relatively fast response time, in whole concentration range (<15 s), and can be used for at least 12 weeks in the pH range of 2.8-5.8. The proposed sensor was successfully used to determination of copper in different water samples and as indicator electrode in potentiometric titration of copper ion with EDTA.     

Novel platinum(II) selective membrane electrode based on 1,3-bis(2-cyanobenzene)triazene

A plasticized poly (vinyl chloride) membrane electrode based on 1,3-bis(2-cyanobenzene)triazene (CBT) for highly selective determination of platinum(II) (in PtCl₄²⁻ form) is developed. The electrode showed a good Nernstian response (29.8 ± 0.3 mV decade⁻¹) over a wide concentration range (1.0 × 10⁻⁶ to 1.0 × 10⁻² mol L⁻¹). The limit of detection was 5.0 × 10⁻⁷ mol L⁻¹. The electrode has a response time of about 40 s, and it can be used for at least 1 month without observing any considerable deviation from Nernstian response. The proposed electrode revealed an excellent selectivity toward platinum(II) ion over a wide variety of alkali, alkaline earth, transition, and heavy metal ions, and it could be used in the pH range of 3.2-5.1. The practical utility of the electrode has been demonstrated by its use in determination of platinum ion in, alloy, tap, mineral and river water samples.     

Aluminum(III)‐selective PVC Membrane Electrode Based on Salicylaldehyde Salicyloyl Hydrazone

A highly selective PVC membrane electrode for Al³⁺ based on salicylaldehyde salicyloyl hydrazone as a neutral carrier has been prepared and studied. The sensor exhibits a good response for Al³⁺ over a linear range of 9.0 × 10^‐6 to 1.0 × 10^‐1 mol/L, with a Nernstian slope of 20.0 ± 0.2 mV/decade and detection limit of 7.0 × 10^‐6 mol/L. Selectivity coefficients determined by the method of separate solution indicate high selectivity for Al³⁺. The response mechanism was discussed in view of UV‐Vis spectroscopy technique and the A.C. impedance technique. It was used as an indicator electrode in potentiometric titration of Al3+ with EDTA and in the determination of Al³⁺ in real samples. The electrode has a relatively fast response time, long life time and satisfactory stability.     

N~1,N~2-Bis[1-(2-hydroxyphenyl)methylidene]ethanedihydrazide as a neutral ionophore for preparation of a new Ho~(3+) PVC-membrane sensor

N¹,N²-Bis[1-（2-hydroxyphenyl）methylidene]ethanedihydrazide（MEH） was used as new compound which plays the role of an excellent ion carrier in the fabrication of a Ho（Ⅲ） membrane electrode.The electrode shows a good selectivity for Ho（Ⅲ） ion with respect to most common cations including alkali,alkaline earth,transition and heavy metal ions.This electrode has a wide linear dynamic range from 1.0×10^-6 to 1.0×10^-2 mol/L with a Nernstian slope of 19.8±0.3 mV per decade and a low detection limit of 5.8×10^-7 mol/L in the pH range of 2.5-9.8,while the response time was rapid（<10 s）.The suggested sensor was applied to the determination of Ho（Ⅲ） ions in tap water and river water samples.     

Highly selective and sensitive thiocyanate membrane electrode based on nickel(II)-1,4,8,11,15,18,22,25-octabutoxyphthalocyanine

A highly selective membrane electrode based on nickel(II)-1,4,8,11,15,18,22,25-octabutoxyphthalocyanine (NOBP) is presented. The proposed electrode shows very good selectivity for thiocyanate ions over a wide variety of common inorganic and organic anions. The sensor displays a near Nernstian slope of −58.7 ± 0.6 mV per decade. The working concentration range of the electrode is 1.0 × 10⁻⁶ to −1.0 × 10⁻¹ M with a detection limit of 5.7 × 10⁻⁷ M (33.06 ng/mL). The response time of the sensor in whole concentration ranges is very short (<10 s). The response of the sensor is independent on the pH range of 4.3-9.8. The best performance was obtained with a membrane composition of 30% PVC, 65% dibutyl phthalate, 3% NOBP and 2% hexadecyltrimethylammonium bromide. It was successfully applied to direct determination of thiocyanate in biological samples, and as an indicator electrode for titration of thiocyanate ions with AgNO₃ solution.     

Zn(II)-selective membrane electrode based on tetra(2-aminophenyl) porphyrin

A new PVC membrane electrode for Zn²⁺ ions based on tetra(2-aminophenyl) porphyrin (TAPP) as membrane carrier is prepared. The sensor exhibits a linear stable response over a wide concentration range (5.0×10⁻⁵ to 1.0×10⁻¹ M) with a slope of 26.5 mV/decade and a limit of detection 3.0×10⁻⁵ M (1.96 ppm). It has a response time of about l0 s and can be used for at least 8 months without any divergence in potential. The propose membrane sensor revealed good selectivities for Zn²⁺ over a wide variety of other metal ions and can be used in pH range of 3.0–6.0. It was successfully applied to the direct determination of zinc in a pharmaceutical sample and also as an indicator electrode in potentiometric titration of Zn²⁺ ions.