Amperometric Nitric Oxide Sensor Based on Poly(Thionine)/Nafion‐Modified Electrode and Its Application in Monitoring Nitric Oxide Release from Rat Kidney

Abstract

A novel amperometric nitric oxide (NO) sensor based on a glassy carbon electrode modified with thionine and Nafion films has been developed. The oxidation peak current of NO increased significantly at the poly(thionine)/Nafion‐modified glassy carbon electrode (GCE), which can be used for the detection of NO. The oxidation peak current was linear with the concentration of nitric oxide over the range from 3.6×10^?7 to 6.8×10^?5 mol · L^?1, and the detection limit was 7.2×10^?8 mol · L^?1. This nitric oxide sensor showed high selectivity to nitric oxide determination, and some potential interference could be eliminated effectively. The nitric oxide sensor has been applied to monitor NO release from rat kidney stimulated by L‐arginine. The results indicated the applicability of the NO sensor to biomedical samples.     

A simple method for determination of urapidil at a glassy carbon electrode modified with poly(sodium4-styrenesulfonate) functionalized graphene

ABSTRACT

A simple, highly sensitive voltammetric method for the determination of urapidil at poly(sodium4-styrenesulfonate) functionalized graphene-modified electrode (PSS-Gr/GCE) was described. Based on the PSS-Gr composites-modified glassy carbon electrode as a simple voltammetric sensor, it exhibited good conductivity and high sensitivity to urapidil. Under the optimize condition, a good linear relationship was obtained between peak currents and urapidil concentrations in the wider range of 2.0 × 10^?9–8.0 × 10^?8 mol L^?1 and 2.0 × 10^?7–2.0 × 10^?5 mol L^?1 with detection limit of 8 × 10^?10 mol L^?1 (S/N = 3). Based on the high sensitivity and good selectivity of the proposed electrode, the proposed method could apply to the detect of urapidil in urapidil sustained release tablets with satisfactory results.     

Poly(4-vinylpyridine-co-aniline)-modified electrode—synthesis, characterization, and application as cadmium(II) ion sensor

A poly(4-vinylpyridine-co-aniline) (poly(4VP-co-Ani))-based solid-state ion sensor for cadmium (Cd) was developed. This was obtained from studies done on a number of selected monomers electropolymerized onto a poly(4vinylpyridine) (P4VP)-modified graphite pencil rod, surface characterizing them and then analyzing their performances as a Cd(II) ion sensor. Among them, the membrane of poly(4VP-co-Ani) at a mole ratio of 0.05:0.15 was found to be the best. The fabricated poly(4VP-co-Ani) solid-state electrode had a linear response of 1?×?10^?6 to 1?×?10^?2?M Cd²⁺, slope of 29.4?±?0.5 mV decade^?1, detection limit of 7.94?×?10^?7?M Cd²⁺, and response time of 15 s at pH 4.5–8.5 with excellent selectivity. The sensor was operationally stable within a period of 3 months. The proposed sensor was tested for determination of Cd²⁺ in environmental, plant, and pharmaceutical samples. The analyses were comparable to the standard atomic absorption spectrophotometric method.     

All-solid-state Cr(III)-selective potentiometric sensor based on Cr(III)-imprinted polymer nanomaterial/MWCNTs/carbon nanocomposite electrode

A novel potentiometric sensor, based on carbon paste electrode (CPE), modified with ion-imprinted polymer (IIP) and multi-walled carbon nanotubes (MWCNTs), is introduced for detection of chromium (III). The IIP nanomaterial was synthesised and characterised by using scanning electron microscopy and Fourier Transform Infrared. The modification of the CPE with the IIP (as a ionophore) resulted in an all-solid-state Cr(III)-selective sensor. However, the presence of appropriate amount of MWCNTs in the electrode composition was found to be necessary to observe Nernstian response. The optimised electrode composition was 76.7% graphite, 14.3% binder, 5% IIP, and 4% CNT. The proposed sensor exhibited Nernstian slope of 20.2 ± 0.2 mV decade^?1 in the working concentration range of 1.0 × 10^?6?1.0 × 10^?1 mol L^?1 (52 µg L^?1–5.2 g L^?1), with a detection limit of 5.9 × 10^?7 mol L^?1 (30.68 µg L^?1) and a fast response time of less than 40 s. It displayed a stable potential response in the pH range of 2–5. It exhibited also high selectivity over some interfering ions. The proposed sensor was successfully applied for the determination of Cr(III) in real samples (sea, river water and soil).     

Molecular Imprinting-Chemiluminescence Sensor for the Determination of Prulifloxacin

Abstract

A selective molecular imprinting-chemiluminescence sensor is developed for the determination of prulifloxacin by using a prulifloxacin-imprinted polymer as recognition material and the cerium(IV)/sodium thiosulfate/prulifloxacin chemiluminescence reaction as the detection system. The linear response range of the sensor is from 8.0 × 10^?8 to 7.0 × 10^?6 mol L^?1 with a detection limit of 2.0 × 10^?8 mol L^?1. The relative standard deviation for 5.0 × 10^?7 mol L^?1prulifloxacin solution is 1.3% (n = 7). This sensor has been applied to the determination of prulifloxacin in urine samples, and the results obtained are satisfactory.     

Selective phosphate sensing using copper monoamino-phthalocyanine functionalized acrylate polymer-based solid-state electrode for FIA of environmental waters

A novel solid-state selective sensor for mono-hydrogen phosphate (HPO₄)^?2 based on copper monoamino phthalocyanine (CuMAPc) ionophore covalently attached to poly (n-butyl acrylate) (PnBA) has been developed and potentiometrically evaluated. The all solid-state sensor was constructed by the application of a thin film of a polymer cocktail containing a CuMAPc–PBDA ionophore and benzyl-dimethylhexadecyl ammonium chloride (BDMHAC) as a lipophilic cationic additive onto a gold electrode pre-coated with the conducting polymer poly (3,4-ethylenedioxythiophene) (PEDOT) as an ion and electron transducer. The sensor with 14.31 % of CuMAPc-PnBA (ionophore II) exhibited a good selectivity for (HPO₄)^?2. The thus constructed sensor discriminated many anions, including F^?, Cl^?, Br^?, I^–, CH₃COO^?, NO₃ ^?, ClO₄ ^?, and SO₄ ^2?. The potentiometric response of the phosphate selective electrode was found to be independent of the pH of sample solution in the range 6–9. The sensor showed a Nernstian slope of ?29.8 ± 0.3 mV conc.^?1 decade^?1 with linear range of 4.0 × 10^?9–1.0 × 10^?2 mol L^?1 and detection limit of 1.0 × 10^?9 mol L^?1 at pH 8.0. The proposed phosphate sensor has been utilized as a detector for the flow injection potentiometric determination of phosphate in different water samples at the nanomolar concentration range.     

Rapid Determination of Pentazocine in Human Plasma and Urine by a Potentiometric Method

Abstract

A fast potentiometric determination method has been reported for pentazocine in human plasma without complicated pretreatments using a coated-wire potentiometric selective electrode. The sensing membrane was made by incorporating of ion-association complexes of pentazocine cation and sodium tetraphenyl borate (NaTPB) in a polyvinyl chloride. The sensor exhibited fast, stable, and linear Nernstian response over the range of 5 × 10^?5 to 0.1 mol L^?1 pentazocine with a slope of 57.8 mV per decade and with detection limit of 3.2 × 10^?5 mol L^?1. The proposed sensor has been used for determination of pentazocine in human plasma and urine.     

Electrochemical sensor for determination of aflatoxin B1 based on multiwalled carbon nanotubes-supported Au/Pt bimetallic nanoparticles

A sensitive and selective imprinted electrochemical sensor for the determination of aflatoxin B₁ (AFB₁) was constructed on a glassy carbon electrode by stepwise modification of functional multiwalled carbon nanotubes (MCNTs), Au/Pt bimetallic nanoparticles (Au/PtNPs), and a thin imprinted film. The fabrication of a homogeneous porous poly o-phenylenediamine (POPD)-grafted Au/Pt bimetallic multiwalled carbon nanotubes nanocomposite film was conducted by controllable electrodepositing technology. The sensitivity of the sensor was improved greatly because of the nanocomposite functional layer; the proposed sensor exhibited excellent selectivity toward AFB₁ owing to the porous molecular imprinted polymer (MIP) film. The surface morphologies of the modified electrodes were characterized using a scanning electron microscope. The performance of the imprinted sensor was investigated by cyclic voltammetry, differential pulse voltammetry, and electrochemical impedance spectroscopy in detail. A linear relationship between the sensor response signal and the logarithm of AFB₁ concentrations ranging from 1?×?10^?10 to 1?×?10^?5 mol L^?1 was obtained with a detection limit of 0.03 nmol L^?1. It was applied to detect AFB₁ in hogwash oil successfully.     

Potentiometric sensor for the nanoscale monitoring of Ni2+ ion in environmental samples by the fabrication of coated pyrolytic graphite electrode based on a novel C–C-coupled compound

Novel ligand 5,5?-((3-nitrophenyl)methylene)bis(2,6-diaminopyrimidin-4(3H)-one) (L) was synthesised and characterised. Preliminary studies on L have showed that it has more affinity towards the Ni²⁺ ion. Thus, the L was used as the electroactive material in the fabrication of poly(vinyl chloride) (PVC)-based membrane sensors such as coated graphite electrode (CGE) and coated pyrolytic graphite electrode (CPGE). Several polymeric membranes were fabricated by incorporating L as ionophore, NaTPB as anion excluders and BA, 1-CN, DBP, DOP and o-NPOE as solvent mediators and their effect on potentiometric response studied. Comparative electroanalytical studies performed on the CGE and CPGE depict that the CPGE with optimised membrane composition of L:PVC:o-NPOE:NaTPB in the ratio of 7:33:58:2 (w/w, mg) exhibited the best response in terms of wide working concentration range from 2.0 × 10^?8 to 1.0 × 10^?1 mol L^?1, (3.64 µg L^?1 –18.2 g L^?1) lower detection limit of 8.1 × 10^–9 mol L^?1 (1.47 µg L^?1) with Nernstian compliance of 29.4 ± 0.2 mV decade^?1 of activity of Ni²⁺ ion in the pH range of 3.5–9.0. The sensor can work satisfactorily in water–acetonitrile and water–methanol mixtures. It can tolerate 30% acetonitrile and 20% methanol content in the mixtures. The sensor showed fast response time of 8 s and could be used successfully for a period of 4 months. The sensor reflects its utility in the quantification of Ni²⁺ ion in real samples and has been successfully employed as an indicator electrode in the potentiometric titration of Ni²⁺ ion with EDTA.     

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.     

Design of a Novel Gadolinium Optical Sensor Based on Immobilization of (Z)-N′-((Pyridine-2-yl) Methylene) Thiophene-2-carbohydrazide on a Triacetylcellulose Membrane and Its Application to the Urine Samples

Abstract

In this work, for the first time we report a highly selective and sensitive Gd(III) optical sensor based on immobilization of (Z)-N′-((pyridine-2-yl) methylene) thiophene-2-carbohydrazide (PMTC) on a triacetylcellulose membrane. This optode exhibits a linear range 5.0 × 10^?8 to 2.0 × 10^?5 M of Gd(III) ion concentration with a detection limit of 1.1 × 10^?8 M. The response time of the newly designed optode was within 1–2 min, depending on the Gd(III) ion concentration. The response of the sensor is independent of the pH solution in the range of 2.0–9.0. It manifests advantages of low detection limit, fast response time, and most significant, very good selectivity with respect to a number of lanthanide ions (La, Ce, Sm, and Eu ions). The proposed sensor could be successfully regenerated with a thiourea solution. Its response was reversible and reproducible (RSD less than 1.3%). This optode was applied to the determination of Gd(III) in synthetic and real samples.     

New Copper(II) Ion-Selective Membrane Electrode Based on Erythromycin Ethyl Succinate as a Neutral Ionophore

Abstract

The potentiometric response characteristics of a new copper(II) ion-selective PVC membrane electrode based on erythromycin ethyl succinate (EES) as ionophore were investigated. The electrode exhibited a Nernstian response to Cu²⁺ ions over the activity range of 1.5 × 10^?2 to 2.0 × 10^?6 mol L^?1 with a limit of detection of 6.3 × 10^?7 mol L^?1. Stable potentials were obtained in the pH range of 5.5–6.5. The potentiometric selectivity coefficients were calculated by using fixed interference method and revealed no important interferences except for Ag⁺. This electrode was successfully applied as an indicator electrode in determination of copper ions in real water samples.     

Fe(III) Ion‐Selective Membrane Electrode Based on 4‐Amino‐6‐methyl‐3‐methylmercapto‐1,2,4‐triazin‐5‐one

Abstract

An original highly selective and sensitive PVC membrane sensor, working as a Fe(III) ion selective electrode and using 4‐amino‐6‐methyl‐3‐methylmercapto‐1,2,4‐triazin‐5‐one (AMMTO) as an ionophore, has been developed. This cetain sensor demonstrated the following performance; a linear dynamic range between 1.0×10^?6 and 1.0×10^?1 M with a near Nernstian slope of 19.4±0.5 mV per decade; a detection limit of 6.8×10^?7 M; characteristically, the best performance was obtained with a membrane composition of 30% poly(vinyl chloride), 65.5% nitrophenyl octyl ether, 2% sodium tetraphenyl borate and 2.5% AMMTO. Furthermore, the potentiometric response of the developed electrode is independent of the solution pH in the range of 2.2–4.8. The sensor possesses the advantages of short conditioning time, fast response time (<15 s) and, especially, great selectivity towards transition and heavy metal ions and some mono, di‐ and trivalent cations. The electrode can be used for at least 9 weeks without any considerable potential divergence. It was effectively used as an indicator electrode in the potentiometric titration of Fe(III) ions with EDTA and the direct determination of Fe³⁺ in different water 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.     

Fabrication of a new nanocomposite modified carbon paste Al<Superscript>3+</Superscript>-ion selective electrode based on <Emphasis Type="Italic">N,N</Emphasis>′-dipyridoxyl (1,2-cyclohexanediamine) (PYCA) as an active material

Construction and feature of a nanocomposite modified carbon paste electrode for aluminum(III) ion determination based on N,N′-dipyridoxyl (1,2-cyclohexanediamine) (PYCA) as a novel selector material will be covered by this paper. The optimum composition, Nernstian slope/linear range/detection limit in the forms of calibration graph, response time, utilizable pH range, repeatability and precision of measurements of the aluminum(III) ion using the new fabricated Al³⁺-CPE was evaluated. The optimal composition which performed over Al⁺³ ion concentration range 1.0 × 10^?8 mol L^?1–1.0 × 10^?1 mol L^?1 with near-Nernstian slope equal 20.9 ± 0.2 mV decade^?1 and low detection limit about 5.0 × 10^?9 mol L^?1, was formed of ionophore (PYCA 3 %), binder (paraffin oil 30 %), modifier [multi-wall carbon nanotubes (MWCNTs) 1 %] & [Nanosilica (NS) 0.5 %], and inert matrix (graphite powder 65.5). The request time to give rise Nernstian response of electrode for concentrations from 1.0 × 10^?8 mol L^?1 to 1.0 × 10^?1 mol L^?1 of Al³⁺ ion solution was estimated about ~6 s. The new Al³⁺-CPE was applied in pH range 2.0–5.0 with no consequential change in potential response. To verify the selectivity of electrode toward aluminum(III) ion in the presence of different metallic cations, matched potential method was used. The obtain results in analytical applications reflect the excellent ability of this electrode to play the role as endpoint indicator electrode in both titration and direct potentiometric measurements.     

Polymeric membrane coated graphite cesium selective electrode based on 4′,4″(5′) di–tert-butyl di-benzo-18-crown-6

A new PVC membrane coated graphite electrode for cesium ion based on 4′,4″(5′)di–tert-butyl di-benzo-18-crown-6 (DTBDB18C6) as ionophore was prepared. The electrode shows a near Nernstian response of 57.0 ± 1.8 mV decade^?1 over a wide activity range of 6.0 × 10^?6–1.0 × 10^?1 mol L^?1 with a limit of detection 4.0 × 10^?6 mol L^?1. The proposed electrode is suitable for use in aqueous solution in the pH range of 3.0–9.5. It has a fast response time of 10 s and can be used for at least 1 month without any considerable divergence in potential. The selectivity coefficients for Cs⁺ ion with respect to ammonium, alkali, alkaline earth and some selected transition metal ions were determined and showed a superior selectivity over Li⁺, Na⁺ and alkaline earth metal ions. The new electrode was applied for determination of Cs⁺ in spiked tap water. The electrode was also used as indicator electrode in potentiometric titration of Cs⁺ with sodium tetraphenyl borate.     

Determination of Pseudoephedrine Hydrochloride in Some Pharmaceutical Drugs by Potentiometric Membrane Sensor Based on Pseudoephedrine–Phosphotungstate Ion Pair

Abstract

An ion-selective electrode (ISE) was developed for the rapid determination of pseudoephedrine hydrochloride (PSEHCl) in pharmaceutical preparations. The electrode incorporates a PVC membrane with a pseudoephedrine–phosphotungstate ion pair complex. The influences of membrane composition, temperature, pH of the test solution, and the interfering ions on the electrode performance were investigated. The sensor exhibits a Nernstian response for pseudoephedrine hydrochloride ions over a relatively wide concentration range (1.0 × 10^?1 to 1.0 × 10^?5 mol L^?1) with a slope of 56.2 ± 0.5 mV per decade at 25°C. It can be used in the pH range 4.0–10.5. The isothermal temperature coefficient of this electrode amounted to 0.0009 V/°C. The membrane sensor was successfully applied to determination of PSEHCl in its tablets and syrup.     

Synthesis of flower-like cuo hierarchical nanostructures as an electrochemical platform for glucose sensing

Flower-like CuO hierarchical nanostructures were synthesized on copper foil substrate through a simple wet chemical route in alkaline media at room temperature. SEM images collected at different reaction times revealed the transformation of initially formed Cu(OH)₂ nanowires to flower-like CuO nanostructures. The hierarchical structure of the as-prepared CuO showed high electrocatalytic activity towards the oxidation of glucose making it a promising electrode material for the development of non-enzymatic glucose sensor. The amperometric sensor exhibited a wide linear response to glucose ranging from 4.5 × 10^?5 to 1.3 × 10^?3 mol L^?1 (R ² = 0.99317) at fixed potential of 0.3 V. The detection limit was 6.9 × 10^?6 mol L^?1 (LOD = 3σ/s) with a sensitivity of 1.71 μA μmol^?1 cm^?2. Moreover, the developed sensor offers a fast amperometric response, good selectivity and stability.     

Facile Synthesis and Characterization of 5-[(3-Methylthiophene-2-yl-methyleneamino)]-2-mercaptobenzimidazole and Its Potentiometric Sensor Application in a Polyvinyl Chloride Membrane for the Determination of Copper(II)

A novel Schiff base designated as 5-[(3-methylthiophene-2-yl-methyleneamino)]-2-mercaptobenzimidazole was synthesized and characterized. A polyvinyl chloride-membrane potentiometric copper(II)-selective sensor was prepared by using the synthesized 5-[(3-methylthiophene-2-yl-methyleneamino)]-2-mercaptobenzimidazole compound. The prepared polyvinyl chloride-membrane copper(II)-selective sensor exhibited very good selectivity and sensitive potentiometric response towards copper(II) ions compared to a wide variety of other cations. The sensor had a fast response time of <5?s, and showed a linear Nerstian behavior to copper(II) ions over a wide concentration range from 1.0?×?10^?5 to 1.0?×?10^?1 mol L^?1 with a slope of 29.2?±?0.7 and correlation coefficient of 0.9998. The prepared polyvinyl chloride-membrane copper(II)-selective sensor was used for 14 weeks without any significant change in its potentiometric response. The potentiometric response of the developed sensor was highly repeatable. Additionally, the developed sensor was used as an indicator electrode for the potentiometric titration of copper(II) ion with ethylenediaminetetraacetic acid. The sensor was also successfully applied to the direct determination of copper(II) ions in tap water, river water, and dam water samples.     

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.