Highly Selective PVC‐Based Membrane Electrode Based on 2,6‐Diphenylpyrylium Fluoroborate

A highly selective PVC‐membrane electrode based on 2,6‐diphenylpyrylium fluoroborate is presented. The electrode reveals a Nernstian potentiometric response for sulfate ion over a wide concentration range (5.0 × 10^?6‐1.0 × 10^?1 M). The electrode has a response time of about 10 s and can be used for at least 2 months without any divergence. The proposed sensor revealed very good selectivities for sulfate over a wide variety of common organic and inorganic anions and could be used over a wide pH range (2.5–9.5). The detection limit of the sensor is 3.0 × 10^?6 M. It was successfully applied to the direct determination of salbutamol, paramomycin tablets, and as an indicator electrode for potentiometric titration of sulfate ions with barium ions.     

A Biomimetic Potentiometric Sensor Using Molecularly Imprinted Polymer for the Cetirizine Assay in Tablets and Biological Fluids

Despite the increasing number of applications of molecularly imprinted polymers (MIPs) in analytical chemistry, the construction of a biomimetic potentiometric sensor remains still challenging. In this work, a biomimetic potentiometric sensor, based on a non‐covalent imprinted polymer was fabricated for the recognition and determination of cetirizine. The MIP was synthesized by precipitation polymerization, using cetirizine dihydrochloride as a template molecule, methacrylic acid (MAA) as a functional monomer and ethylene glycol dimethacrylate (EGDMA) as a cross linking agent. The sensor showed high selectivity and a sensitive response to the template in aqueous system. The MIP‐modified electrode exhibited Nernstian response (28.0±0.9 mV/decade) in a wide concentration range of 1.0×10^?6 to 1.0×10^?2 M with a lower detection limit of 7.0×10^?7 M. The electrode has response time of ca. 20 s, high performance, high sensitivity, and good long term stability (more than 5 months). The method was satisfactory and used to the cetirizine assay in tablets and biological fluids.     

Determination of Fluoride Ions in Mouthwash Samples by a PVC Membrane Samarium(III) Sensor

Abstract

In this study, a new ion-selective electrode for Sm³⁺ is described, illustrating 2-[(E)-1-(1H-pyrrol-2-yl)methylidene]-1-hydrazinecarbothioamide (PMH) in a poly(vinylchloride) (PVC) membrane with nitrobenzene (NB) as a plasticizer and sodium tetraphenyl borate (NaTPB) as an anionic additive. The proposed sensor exhibited a Nernstian response for Sm³⁺ ions over a wide concentration range between 1.0 × 10^?2 and 1 × 10^?6 M, with a detection limit of 5.2 × 10^?7 M in the pH range of 4.2–8.5. Moreover, the sensor displayed the Nernstian slope of 19.8 ± 0.3 mV per decade, having a fast response time within 10 s over the entire concentration range. This electrode presented very good selectivity and sensitivity toward the Sm³⁺ ions over a wide variety of cations, including alkali, alkaline earth, transition-metal, and heavy-metal ions. It was used as an indicator electrode in the potentiometric titration of Sm³⁺ ions with EDTA. The membrane sensor was also applied to the determination of fluoride ions in mouthwash samples.     

Lead-Selective Membrane Potentiometric Sensor Based on a Recently Synthesized Bis(Anthraquinone) Sulfide Derivative

Abstract

A new PVC membrane electrode for lead ions, based on bis[(1-hydroxy-9,10-anthraquinone)-2-methyl]sulfide as membrane carrier, was prepared. The sensor exhibits a Nernstian response for Pb²⁺ over a wide concentration range (5.6 × 10^?3-4.0 × 10^?6 M). It has a response time of about 30 s and can be used for at least 3 months without any divergence in potentials. The proposed membrane sensor revealed good selectivities for Pb²⁺ over a wide variety of other metal ions. It was used as an indicator electrode in potentiometric titration of lead ion.     

Erbium(III) PVC Membrane Ion-Selective Sensor based on 4-(2-Thiazolylazo)resorcinal

Abstract

4-(2-Thiazolylazo)resorcinol (TR) was used as a new compound to play the role of an excellent ion carrier in the fabrication of an Er(III) membrane electrode. The electrode shows a very good selectivity toward Er(III) ions over a wide variety of cations, including alkali, alkaline earth, transition, and heavy-metal ions. The proposed sensor exhibits a Nernstian behavior (with slope of 19.6 ± 0.6 mV per decade) over a wide concentration range (1.0 × 10^?6 to 1.0 × 10^?2 M). The detection limit of the sensor is 6.6 × 10^?7 M. It has a very short response time, in the whole concentration range (～10 s), and can be used for at least 12 weeks in the pH range of 2.8–9.3. The proposed sensor was successfully applied as an indicator electrode for the potentiometric titration of a Er(III) solution, with EDTA. It was also successfully applied to the F^? ion determination in some mouthwashing solutions.     

A Novel Sulfate Polymeric Membrane Sensor Based on a New Bis‐Pyrylium Derivative

A novel ion‐selective polymeric membrane sensor based on pyrylium‐4,4‐(1,4‐phenylen) bis[2,6‐bis(2‐naphthyl)]‐bis[tetrafluoroborate] (PBGNB) as an excellent sensing material is successfully developed. The electrode possesses the advantages of a very low detection limit (5.0×10^?8 M), a wide working concentration range (1.0×10^?8?1.0×10^?1 M) and specially, a high sulfate selectivity over most common organic and inorganic anions. The sensor displays Nernstian behavior (slope of 29.5±0.5 mV per decade) in a wide pH range (3.0–8.5). It shows a short response time in the whole concentration range (ca. 10 s). The electrode was used as an indicator electrode in the potentiometric titration of sulfate ions with barium ions. The proposed sensor was successfully applied to the direct determination of salbutamol sulfate and paromomycin sulfate.     

Development of an Electrochemical Sensor for Selective Determination of Dopamine Based on Molecularly Imprinted Poly(p-aminothiophenol) Polymeric Film

In this study, a molecularly imprinted electrochemical sensor (MIP/DA) was investigated for selective and sensitive determination of dopamine (DA) by electrochemical polymerization of p-aminothiophenol in the presence of DA on gold electrode. According to electrochemical behaviour of the sensor, gained through cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS), MIP/DA sensor showed distinctive electron transfer characteristics in comparison to the non-imprinted (NIP/DA) sensor. Besides the MIP/DA sensor showed high selectivity for dopamine through its analyte specific cavities. The sensor had a broad working range of 5.0×10⁻⁸–2.0×10⁻⁷ M with a limit of detection (LOD) of 1.8×10⁻⁸ M and the developed sensor was successfully applied for determination of dopamine in pharmaceutical samples.     

Original Potentiometric Ytterbium(III) PVC-Membrane Sensor Based on N1,N2-Bis-[1-(2-hydroxy-1,2-diphenyl)ethylidene]ethanedihydrazide

Abstract

In this work, we describe the construction, performance, and applications of an original ytterbium(III) sensor based on N¹,N²-bis-[1-(2-hydroxy-1,2-diphenyl)ethylidene]ethanedihydrazide (BHDEH), which acts as a suitable carrier. Because it has a low detection limit of 4.2 × 10^?7 M, the sensor response for the Yb(III) ion is Nernstian over a wide concentration range: four decades of concentration (1.0 × 10^?6 to 1.0 × 10^?2 M). The response time of the electrode is less than 10 s, it can be used in the pH range of 3.2–8.3, and its duration is at least 2 months without any considerable potential divergence. The sensor revealed very good selectivity for Yb(III) in the presence of several metal ions. To investigate the sensor analytical applicability, it was tested as an indicator electrode in the potentiometric titration of Yb(III) solution with standard EDTA solution. The proposed electrode was also used to determine fluoride ions in mouthwash.     

Iodide‐Selective Electrode Based on Copper Phthalocyanine

Copper phthalocyanine was used as ion carrier for preparing polymeric membrane selective sensor for detection of iodide. The electrode was prepared by incorporating the ionophore into plasticized poly(vinyl chloride) (PVC) membrane, coated on the surface of graphite electrode. This novel electrode shows high selectivity for iodide with respect to many common inorganic and organic anions. The effects of membrane composition, pH and the influence of lipophilic cationic and anionic additives and also nature of plasticizer on the response characteristics of the electrode were investigated. A calibration plot with near‐Nernestian slope for iodide was observed over a wide linear range of five decades of concentration (5×10^?6?1×10^?1 M). The electrode has a fast response time, and micro‐molar detection limit (ca. 1×10^?6 M iodide) and could be used over a wide pH range of 3.0–8.0. Application of the electrode to the potentiometric titration of iodide ion with silver nitrate is reported. This sensor is used for determination of the minute amounts of iodide in lake water samples.     

Cobalt(II)-selective membrane electrode based on N,N′-di(thiazol-2-yl)formimidamide

A new PVC-membrane electrode for Co²⁺ ions based on N,N′-di(thiazol-2-yl)formimidamide (TF) as membrane carrier has been developed. The electrode resulted in Nernstian response (29.5?±?0.4?mV decade^?1) for Co²⁺ ion over a wide concentration range (2.5?×?10^?7 ?1.0?×?10^?1?M) with a detection limit of 6.1?×?10^?8?M. The sensor has a response time of about 10?s, and can be used for at least 2 months without observing any deviation from the Nernstain response. The electrode revealed good selectivity towards cobalt(II) ion over a wide variety of alkali, alkaline earth, transition, and heavy metal ions and could be used in the pH range 2.0–7.0. The electrode was used for determination of Co²⁺ in real samples.     

Determination of cerium(III) ions in soil and sediment samples by Ce(III) PVC-based membrane electrode based on 2,5-dioxo-4-imidazolidinyl

2,5-Dioxo-4-imidazolidinyl was used as an excellent sensing material in the preparation of a PVC membrane for a Ce(III)-selective sensor. The electrode shows a good selectivity for the Ce(III) ion with respect to most common cations including alkali, alkaline earth, transition, and heavy metal ions. The developed sensor exhibits a wide linear response with a slope of 19.6?±?0.3 mV per decade over the concentration range of 1.0?×?10^?6 to 1.0?×?10^?1 M, while the illustrated detection limit is 5.7?×?10^?7 M of Ce(III) ions. Moreover, it is concluded that the sensor response is pH-independent in the range of 3.1–9.8. The applications of the recommended electrode include the determination of concentration of Ce(III) ions in soil and sediment samples, validation with CRM's, and the Ce(III) ion potentiometric titration with EDTA as an indicator electrode.     

Novel Bromide PVC‐Based Membrane Sensor Based on Iron(III)‐Salen

A novel bromide PVC‐based membrane sensor, based on iron(III)‐salen (IS) as an electroactive material, is successfully developed. The sensor possesses the advantages of low detection limit (6.0×10^?6), wide working concentration range (7.0×10^?6–1.0×10^?1 M), Nernstian behavior (slope of 59.0±0.5 mV per decade), low response time (<15 s), wide working pH range (3–9), and specially, high bromide selectivity over a wide variety of organic and inorganic anions, specially iodide, chloride, and hydroxide ions. The electrode was used in the direct potentiometric determination of hyoscine butylbromide, and as an indicator electrode in potentiometric titration of bromide ions with silver ions.     

Application of Tetra Cyclohexyl Tin(IV) as an Anionic Carrier for the Construction of a New Salicylate Membrane Sensor

A new tin complex namely tetracyclohexyl tin(IV) (TCHT) was synthesized and used as the ion carrier for the construction of a highly selective salicylate sensor. This sensor shows a Nernstian response to salicylate ions over a very wide concentration (1.0 × 10^?7–1.0 × 10^?1 M) in a pH range of 5.5–10.5. The optimum selectivity and response could be obtained for a membrane incorporating 30% PVC, 61% BA, 3% of cationic additive (HTAB) and 6% of TCHT. The response time of the electrode is very short in the whole concentration range (15 s). The electrode also shows an excellent discriminating ability for salicylate ions with respect to the most common organic and inorganic anions including chloride, sulfate, nitrate, nitrite, cyanide, sulfite, iodide, thiocyanate, phosphate, acetate, oxalate, citrate, and tartarate ions. The detection limit of the proposed sensor is 8.0 × 10^?8 M. The electrode was successfully used for determining the concentration of salicylate ion in synthetic serums.     

A Novel Al(III)‐Selective Electrochemical Sensor Based on N,N′‐Bis(salicylidene)‐1,2‐phenylenediamine Complexes

A polyvinylchloride membrane sensor based on N,N′‐bis(salecylidene)‐1,2‐phenylenediamine (salophen) as membrane carrier was prepared and investigated as a Al³⁺‐selective electrode. The sensor exhibits a Nernstian response toward Al(III) over a wide concentration range (8.0×10^?7–3.0×10^?2 M), with a detection limit of 6.0×10^?7 M. The potentiometric response of the sensor is independent of the pH of the test solution in the pH range 3.2–4.5. The electrode possesses advantages of very fast response and high selectivity for Al³⁺ in comparison with alkali, alkaline earth and some heavy metal ions. The sensor was used as an indicator electrode, in the potentiometric titration of aluminum ion and in determination of Al³⁺ contents in drug, water and waste water samples.     

A Novel Molecularly Imprinted Photoelectrochemical Sensor Based on g‐C3N4‐AuNPs for the Highly Sensitive and Selective Detection of Triclosan

A novel molecularly imprinted polymer (MIP) photoelectrochemical sensor was fabricated for the highly sensitive and selective detection of triclosan. The MIP photoelectrochemical sensor was fabricated using graphite‐like carbon nitride (g‐C₃N₄) and gold nanoparticles (AuNPs) as photoelectric materials. The MIP/g‐C₃N₄‐AuNPs sensor used photocurrent as the detection signal and was triggered by ultraviolet light (UV‐Light 365 nm). g‐C₃N₄‐AuNPs was immobilized on indium tin oxide electrodes to produce the photoelectrochemically responsive electrode of the MIP/g‐C₃N₄‐AuNPs sensor. A MIP layer of poly‐o‐phenylenediamine was electropolymerized on the g‐C₃N₄‐AuNPs‐modified electrode to act as the recognition element of the MIP/g‐C₃N₄‐AuNPs sensor and to enable the selective adsorption of triclosan to the sensor through specific binding. Under optimal experimental conditions, the designed MIP/g‐C₃N₄‐AuNPs sensor presented high sensitivity for triclosan with a linear range of 2×10⁻¹² to 8×10⁻¹⁰ M and a limit of detection of 6.01×10⁻¹³ M. Moreover, the MIP/g‐C₃N₄‐AuNPs sensor showed excellent selectivity. The sensor had been successfully applied in the analysis of toothpaste samples.     

Chromium(III) Potentiometric Sensor Based on Para‐Tertiary‐Butyl Calix[4]arene

A new chromium(III) PVC membrane sensor incorporating p‐tertiary‐butyl calix[4]arene as ionophore, potassium tetrakis as additive and dibutyl phthalate (DBP) as plasticizer was constructed. The electrode exhibited an excellent potentiometric response over a wide concentration range of 1.0×10^?7–1.0×10^?1 M with a Nernstian slope of 20±0.5 mV per decade. The detection limit was 5.0×10^?8 M. The electrode showed a better performance over a pH range of 3.0–8.0, and had a short response time of about <15 s.The electrode was successfully applied to potentiometric titration of Cr (III) with EDTA and for direct determination of chromium(III) in waste water.     

Direct determination of pesticides in vegetable samples using gold nanoelectrode ensembles

Gold nanowires were produced by electrodeposition in polycarbonate membrane, with an average diameter of 200 nm and a height of about 2 μm. The nanowire array prepared by the proposed method can be considered as nanoelectrode ensembles (NEEs). An amperometric pesticides sensor based on gold NEEs has been developed and used for determination of phoxim and dimethoate in vegetable samples. The electrochemical performance of the gold NEEs has also been studied by the amperometric method. The electrode provided a linear response over a concentration range of 5.9 × 10^?5 to 1.2 × 10^?2 M for phoxim with a detection limit of 4.8 × 10^?6 M and 6.3 × 10^?5 to 1.1 × 10^?2 M for dimethoate. This sensor displayed high sensitivity and selectivity, long-term stability and wide linear range. In addition, the ellipsis of enzyme and the reactivation of enzyme make the operation simple. This sensor has been used to determine pesticides in a real vegetable sample.     

Subnanomolar determination of a beryllium ion by a novel Be(II) microsensor based on 4-nitrobenzo-9-crown-3-ether

In this work, for the first time, we introduce a highly selective and sensitive Be(II) microsensor. 4-nitrobenzo-9-crown-3-ether (NBCE) was used as a membrane-active component to prepare a Be(II)-selective polymeric membrane microelectrode. The electrode exhibits a Nernstian response toward Be(II) ions over a very wide concentration range (1.0 × 10⁻⁴–1.0 × 10⁻¹⁰ M), with a detection limit of 3.5 × 10⁻¹¹ M (∼350 pg/L). In fact, the electrode presents a fast response time in the whole concentration range (6 s). The proposed microelectrode can be used for at least six weeks without any considerable divergence in the potentials. The proposed membrane sensor revealed a selectivity toward Be(II) ions over a wide variety of other metal ions including common alkali, alkaline-earth, and rare-earth ions. It could be used in the pH range of 3.0–11.5. The microelectrode was successfully used as an indicator electrode for the titration of 20 mL of 1.0 × 10⁻⁶ M Be²⁺ solution with 1.0 × 10⁻⁴ M of EDTA. It was also applied to the direct determination of beryllium ions in beryl and binary mixtures. The text was submitted by the authors in English.     

Solid-state ion selective electrode based on polypyrrole conducting polymer nanofilm as a new potentiometric sensor for Zn2+ ion

A pencil graphite electrode (PGE) electrodeposited by a polypyrrole conducting polymer doped with tartrazine (termed as PGE/PPy/Tar) was prepared and used as a zinc (II) solid-state ion-selective electrode. For the preparation of the zinc sensor electrode, electrodeposition of a polypyrrole nanofilm was carried out potentiostatically (E _app?=?0.75 V vs SCE) in a solution containing 0.010 M pyrrole and 0.001 M tartrazine trisodium salt. A pencil graphite and Pt wire were used as working and auxiliary electrodes, respectively. The introduced electrode in the current paper can be fabricated simply and was found to possess high selectivity, exhibited wide working concentration range, sufficiently rapid response, potential stability, and very good sensitivity to Zn (II) ion. The sensor electrode showed a linear Nernstian response over the range of 1.0?×?10^?5 to 1.0?×?10^?1 M with a slope of 28.23 mV per decade change in zinc ion concentration. A detection limit of 8.0?×?10^?6 M was obtained. The optimum pH working of the electrode was found to be 5.0.     

A Copper(II) Ion‐Selective Potentiometric Sensor Based on N,N′,N″,N′′′‐Tetrakis(2‐pyridylmethyl)‐1,4,8,11‐tetraazacyclotetradecane in PVC Matrix

The simple PVC‐based membrane containing N,N′,N″,N′′′‐tetrakis(2‐pyridylmethyl)‐1,4,8,11‐tetraazacyclotetradecane (tpmc) as an ionophore and dibutyl phthalate as a plasticizer, directly coated on a glassy carbon electrode was examined as a new sensor for Cu²⁺ ions. The potential response was linear within the concentration range of 1.0×10^?1–1.0×10^?6 M with a Nernstian slope of 28.8 mV/decade and detection limit of 7.0×10^?7 M. The electrode was used in aqueous solutions over a wide pH range (1.3–6). The sensor exhibited excellent selectivity for Cu²⁺ ion over a number of cations and was successfully used in its determination in real samples.