Highly selective differential pulse voltammetric determination of phenazopyridine using MgCr2O4 nanoparticles decorated MWCNTs-modified glassy carbon electrode.

A selective modified glassy carbon electrode based on multiwall carbon nanotubes decorated with MgCr2O4 nanoparticles was fabricated and used for the determination of phenazopyridine using differential pulse voltammetry. The electrochemical response of the modified electrode toward phenazopyridine was characterized by different electrochemical methods including differential pulse voltammetry (DPV), cyclic voltammetry (CV), and impedance spectroscopy. The prepared electrode showed an efficient synergic effect on the oxidation of phenazopyridine at pH 6.0. The oxidation peak current was proportional to the concentration of phenazopyridine from 0.05 to 7.5 μmol L(-1). The detection limit was 0.025 μmol L(-1). The applicability of the method was confirmed with satisfactory results obtained through the assay of phenazopyridine in human plasma, urine samples, and pharmaceuticals.

Ensafi AA ，Arashpour B ，Rezaei B ，Allafchian AR ... -  《-》

A sensitive and selective voltammetric sensor based on multiwall carbon nanotubes decorated with MgCr₂O₄ for the determination of azithromycin.

In this report, we synthesized MgCr(2)O(4) nanoparticles and then multiwall carbon nanotubes were decorated with the MgCr(2)O(4) nanoparticles. The characteristics of the new materials were studied with different techniques such as transmission electron microscopy, Fourier transform infrared spectroscopy, atomic force microscopy and electrochemical impedance spectroscopy. The multiwall carbon nanotubes decorated with MgCr(2)O(4) nanoparticles were used as a new mediator for voltammetric determination of azithromycin. The oxidation peak of azithromycin was appeared at a potential of about 720 mV at a surface of the modified electrode. Differential pulse voltammetry exhibited two wide linear dynamic ranges of 0.25-4.0 and 4.0-10.0 μmol L(-1) azithromycin with a detection limit of 0.07 μmol L(-1) at pH 7.0. The influence of potential interfering compounds on the selectivity was studied. Finally, the modified electrode showed good sensitivity, selectivity and stability for the determination of azithromycin in real samples.

Ensafi AA ，Allafchian AR ，Rezaei B 《-》

Voltammetric behavior of dopamine at a glassy carbon electrode modified with NiFe(2)O(4) magnetic nanoparticles decorated with multiwall carbon nanotubes.

Voltammetric behavior of dopamine was studied on a glassy carbon electrode (GCE) modified-NiFe(2)O(4) magnetic nanoparticles decorated with multiwall carbon nanotubes. Impedance spectroscopy and cyclic voltammetry were used to characterize the behavior of dopamine at the surface of modified-GCE. The modified electrode showed a synergic effect toward the oxidation of dopamine. The oxidation peak current is increased linearly with the dopamine concentration (at pH7.0) in wide dynamic ranges of 0.05-6.0 and 6.0-100μmolL(-1) with a detection limit of 0.02μmolL(-1), using differential pulse voltammetry. The selectivity of the method was studied and the results showed that the modified electrode is free from interference of organic compounds especially ascorbic acid, uric acid, cysteine and urea. Its applicability in the determination of dopamine in pharmaceutical, urine samples and human blood serum was also evaluated. The proposed electrochemical sensor has appropriate properties such as high selectivity, low detection limit and wide linear dynamic range when compared with that of the previous reported papers for dopamine detection.

Ensafi AA ，Arashpour B ，Rezaei B ，Allafchian AR ... -  《-》

Simultaneous voltammetric determination of tyrosine and paracetamol using a carbon nanotube-graphene nanosheet nanocomposite modified electrode in human blood serum and pharmaceuticals.

A novel, simple and selective electrochemical method was investigated for the single or simultaneous determination of tyrosine (Tyr) and paracetamol (PC) in aqueous media (phosphate buffer solution, pH 7.5) on MWCNTs-graphene nanosheet nanocomposite modified glassy carbon electrode (MWCNTs-GNS/GCE) using differential pulse voltammetry (DPV). The MWCNTs-GNS/GCE displayed high effective surface area, high porosity, more reactive sites and excellent electrochemical catalytic activity toward the oxidation of Tyr and PC. The peak current of differential pulse voltammograms of Tyr and PC increased linearly with their concentration in the ranges of 0.90-95.4 μM Tyr and 0.80-110.0 μM PC. The detection limits for Tyr and PC were 0.19 μM and 0.10 μM, respectively. The proposed sensor was successfully applied for the determination of Tyr and PC in human blood serum and pharmaceutical samples.

Arvand M ，Gholizadeh TM 《-》

Characterization of carbon nanotubes decorated with NiFe2O4 magnetic nanoparticles as a novel electrochemical sensor: application for highly selective determination of sotalol using voltammetry.

A magnetic nano-composite of multiwall carbon nanotube, decorated with NiFe2O4 nanoparticles, was synthesized with citrate sol-gel method. The multiwall carbon nanotubes decorated with NiFe2O4 nanoparticles (NiFe2O4-MWCNTs) were characterized with different methods such as Fourier transform infrared spectroscopy (FT-IR), transmission electron microscopy (TEM), atomic force microscopy (AFM), vibrating sample magnetometer (VSM), cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS). The new nano-composite acts as a suitable electrocatalyst for the oxidation of sotalol at a potential of 500 mV at the surface of the modified electrode. Linear sweep voltammetry exhibited two wide linear dynamic ranges of 0.5-1000 μmol L(-1) sotalol with a detection limit of 0.09 μmol L(-1). The modified electrode was used as a novel electrochemical sensor for the determination of sotalol in real samples such as pharmaceutical, patient and safe human urine.

Ensafi AA ，Allafchian AR ，Rezaei B ，Mohammadzadeh R ... -  《-》