Modified multiwall carbon nanotubes paste electrode as a sensor for simultaneous determination of 6-thioguanine and folic acid using ferrocenedicarboxylic acid as a mediator

An electrochemical nanocomposite modified carbon paste electrode as a sensor for simultaneous determination of hydrazine and phenol in water and wastewater samples

In this study, we report preparation of a high sensitive electrochemical sensor for determination of hydrazine in the presence of phenol in water and wastewater samples. In the first step, we describe synthesis and characterization of ZnO/CNTs nanocomposite with different methods such as transmission electron microscopy (TEM) and X-ray diffraction (XRD). In the second step, application of the synthesis nanocomposite describes the preparation of carbon paste electrode modified with N-(4-hydroxyphenyl)-3,5-dinitrobenzamide as a high sensitive and selective voltammetric sensor for determination of hydrazine and phenol in water and wastewater samples. The mediated oxidation of hydrazine at the modified electrode was investigated by cyclic voltammetry, chronoamperometry, and electrochemical impedance spectroscopy (EIS). Also, the values of catalytic rate constant (k) and diffusion coefficient (D) for hydrazine were calculated. Square wave voltammetry (SWV) of hydrazine at the modified electrode exhibited two linear dynamic ranges with a detection limit (3σ) of 8.0 nmol L(-1). SWV was used for simultaneous determination of hydrazine and phenol at the modified electrode and quantitation of hydrazine and phenol in some real samples by the standard addition method.

A voltammetric sensor based on NiO/CNTs ionic liquid carbon paste electrode for determination of morphine in the presence of diclofenac

A novel ionic liquid modified NiO/CNTs carbon paste electrode (IL/NiO/CNTCPE) had been fabricated by using hydrophilic ionic liquid 1-methyl-3-butylimidazolium chloride [MBIDZ]Cl as a binder. The cyclic voltammogram showed an irreversible oxidation peak at 0.61 V (vs. Ag/AgCl(sat)), which corresponded to the oxidation of morphine. Compared to common carbon paste electrode, the electrochemical response was greatly improved for morphine electrooxidation. This modified electrode exhibited a potent and persistent electron mediating behavior followed by well separated oxidation peaks of morphine and diclofenac. Detection limit of morphine was found to be 0.01 μM using square wave voltammetry (SWV) method. The proposed sensor was successfully applied for the determination of morphine in human urine and pharmaceutical samples.

A new strategy for determination of hydroxylamine and phenol in water and waste water samples using modified nanosensor

A carbon paste electrode modified with p-chloranil and carbon nanotubes was used for the sensitive and selective voltammetric determination of hydroxylamine (HX) and phenol (PL). The oxidation of HX at the modified electrode was investigated by cyclic voltammetry (CV), chronoamperommetry, and electrochemical impedance spectroscopy. The values of the catalytic rate constant (k), and diffusion coefficient (D) for HX were calculated. Square wave voltammetric peaks current of HX and PL increased linearly with their concentrations at the ranges of 0.1-172.0 and 5.0-512.0 μmol L(-1), respectively. The detection limits for HX and PL were 0.08 and 2.0 μmol L(-1), respectively. The separation of the anodic peak potentials of HX and PL reached to 0.65 V, using square wave voltammetry. The proposed sensor was successfully applied for the determination of HX and PL in water and wastewater samples.

VOLTAMMETRIC DETERMINATION OF ACETOPHOS IN WATER SAMPLES AT CNTPE

In this paper, a sensitive differential pulse voltammetric method to determine the residues of acetophos in water samples at CNTPE were reported. The significance of CNTPE is to result in low detection limits, high sensitivities, reduction of over-potentials, high mechanical strength and high conductivity and resistance to surface fouling. The universal buffer with pH range 2.0–6.0 is used as supporting electrolyte. Cyclic voltammetry employed to evaluate electrode mechanism and number of electrons involved in reduction process were found out by using Millicoulometry and the product collected by applying Controlled potential electrolysis. Experimental conditions such as accumulation potential, accumulation time and scan rate were optimized. Calculations were made by standard addition method.

A novel modified carbon paste electrode based on NiO/CNTs nanocomposite and (9, 10-dihydro-9, 10-ethanoanthracene-11, 12-dicarboximido)-4-ethylbenzene-1, 2-diol as a mediator for simultaneous determination of cysteamine, nicotinamide adenine dinucleotide and folic acid

A carbon paste electrode (CPE) modified with (9, 10-dihydro-9, 10-ethanoanthracene-11, 12-dicarboximido)-4-ethylbenzene-1, 2-diol (DEDE) and NiO/CNTs nanocomposite was used for the sensitive voltammetric determination of cysteamine (CA), nicotinamide adenine dinucleotide (NADH) and folic acid (FA) for the first time. The synthesized materials were characterized with different methods such as XRD, cyclic voltammetry, electrochemical impedance spectroscopy (EIS) and square wave voltammetry (SWV). The modified electrode exhibited a potent and persistent electron mediating behavior followed by well-separated oxidation peaks of CA, NADH and FA. The peak currents were linearly dependent on CA, NADH and FA concentrations using square wave voltammetry (SWV) method in the ranges of 0.01-250, 1.0-500, and 3.0-550 µmol L⁻¹, with detection limits of 0.007, 0.6, and 0.9 µmol L⁻¹, respectively. The modified electrode was used for the determination of CA, NADH and FA in biological and pharmaceutical samples.

Synthesis and application of FePt/CNTs nanocomposite as a sensor and novel amide ligand as a mediator for simultaneous determination of glutathione, nicotinamide adenine dinucleotide and tryptophan

In this study, we report the synthesis and application of a FePt/CNTs nanocomposite as a highly sensitive sensor and novel amide ligand (9,10-dihydro-9,10-ethanoanthracene-11,12-dicarboximido)-4-ethylbenzene-1,2-diol as a mediator for the determination of glutathione (GSH), nicotinamide adenine dinucleotide (NADH) and tryptophan (Trp). The synthesized materials were characterized with different methods such as NMR, IR spectroscopy, TEM, XRD, FESEM, cyclic voltammetry, electrochemical impedance spectroscopy and square wave voltammetry (SWV). The modified electrode exhibited a potent and persistent electron mediating behavior followed by well-separated oxidation peaks of GSH, NADH and Trp. The peak currents were linearly dependent on GSH, NADH and Trp concentrations in the range of 0.08-220, 1.0-400 and 5.0-500 μmol L(-1), with detection limits of 0.05, 0.8 and 1.0 μmol L(-1), respectively. The modified electrode was used for the determination of these compounds in real samples.

Photocatalytic Decomposition of Methyl Red Dye by Using Nanosized Zinc Oxide Deposited on Glass Beads in Various pH and Various Atmosphere

Photocatalytic decomposition of methyl red (MR) as a pollutant in wastewater samples is investigated in this study. This photodegradation was investigated in water in neutral, alkaline, and acidic media under external UV light irradiation by zinc oxide nanosized catalysts on granule glass. The effect of four atmosphere types including air, nitrogen, oxygen, and argon was investigated. Finally, it was found that photodecomposition using nanosized ZnO layered on glass is a new alternative route for efficient wastewater treatment. The results showed that the titled dye is degraded by various rate under different atmosphere and pH.

Synthesis of Silver Nanoparticles UsingTriticum aestivumand Its Effect on Peroxide Catalytic Activity and Toxicology

The synthesis of stable silver nanoparticles using bioreduction method was investigated. Biological synthesis of silver nanoparticles usingTriticum aestivum(khapali ghahu) extract was investigated. The effect of a specific variety of plants and how it affects the growth of silver nanoparticles was investigated in our work and it was polydispersed. UV-visible spectroscopy was used to monitor the formation of silver nanoparticles within 15 minutes. The peaks in XRD pattern are in good agreement with those of face-centered-cubic form of metallic silver. Further the IR and TEM shows confirmation of nanocrystalline nature of silver nanoparticles. These nanoparticles dislodged by ultrasonication showed an absorption peak at 430 nm in UV-visible spectrum corresponding to the Plasmon resonance of silver nanoparticles. UV-visible titration experiments showed evidence that silver nanoparticles facilitate hydrogen peroxide reduction showing excellent catalytic activity at 200 μL. In this preliminary toxicology study, Earthworm toxicology we checked and is stable up to 1500 ppm concentration. The use of plant extract for silver nanoparticles synthesis offers the benefits of eco-friendliness and amenability for large-scale production.

A new strategy for the selective determination of glutathione in the presence of nicotinamide adenine dinucleotide (NADH) using a novel modified carbon nanotube paste electrode

A novel electrochemical sensor for the simultaneous determination of glutathione (GSH) and nicotinamide adenine dinucleotide (NADH) is described. The sensor is based on a carbon paste electrode (CPE) modified with benzamide derivative and multiwall carbon nanotubes. This mixture makes a modified electrode that is sensitive for the electrochemical detection of these compounds. Under optimum conditions and at pH 7.0, oxidation of GSH occurs at a potential of about 330 mV less positive than that at an unmodified CPE. The voltammetric peak currents are linearly dependent on GSH and NADH concentrations in the ranges 0.09-300 μmol L(-1) GSH and 5.0-600 μmol L(-1) NADH. The detection limits found for GSH and NADH were 0.05 μmol L(-1) and 1.0 μmol L(-1), respectively. The electrochemical sensor was also used for the determination of GSH in urine, pharmaceutical and hemolysed erythrocyte samples.

New voltammetric strategy for simultaneous determination of N-acetylcysteine and folic acid using a carbon nanotube modified glassy carbon electrode

A novel 1-benzyl-4-ferrocenyl-1H-[1,2,3]-triazole (BFT)/carbon nanotube modified glassy carbon electrode (BFT-CNT-GCE) was prepared for the simultaneous determination of N-acetylcysteine (NAC) and folic acid (FA). Cyclic voltammetry (CV), chronoamperometry (CHA), and square wave voltammetry (SWV) methods were used to investigate the modified electrode for the electrocatalytic oxidation of NAC and FA in aqueous solutions. The separation of the oxidation peak potentials for NAC-FA was about 280 mV. The calibration curve obtained for NAC was in the range of 0.1-600.0 μM. The detection limit (S/N=3) was 62.0±2.0 nM for NAC. The diffusion coefficient and the catalytic rate constant for the oxidation of NAC at the modified electrode were calculated as (3.5±0.2)×10(-5) cm(2) s(-1) and (9.85±0.4)×10(-4) M(-1) s(-1), respectively. The method was employed for the determination of NAC and FA in some real samples.

Voltammetric determination of homocysteine using multiwall carbon nanotube paste electrode in the presence of chlorpromazine as a mediator

We propose chlorpromazine (CHP) as a new mediator for the rapid, sensitive, and highly selective voltammetric determination of homocysteine (Hcy) using multiwall carbon nanotube paste electrode (MWCNTPE). The experimental results showed that the carbon nanotube paste electrode has a highly electrocatalytic activity for the oxidation of Hcy in the presence of CHP as a mediator. Cyclic voltammetry, double potential step chronoamperometry, and square wave voltammetry (SWV) are used to investigate the suitability of CHP at the surface of MWCNTPE as a mediator for the electrocatalytic oxidation of Hcy in aqueous solutions. The kinetic parameters of the system, including electron transfer coefficient, and catalytic rate constant were also determined using the electrochemical approaches. In addition, SWV was used for quantitative analysis. SWV showed wide linear dynamic range (0.1-210.0 μM Hcy) with a detection limit of 0.08 μM Hcy. Finally, this method was also examined as a selective, simple, and precise electrochemical sensor for the determination of Hcy in real samples.