Vitamin B12 incorporated with multiwalled carbon nanotube composite film for the determination of hydrazine

Spectrophotometric determination of pico-molar level of hydrazine by using Alizarin red in water and urine samples

In this paper, very simple and rapid sensor has been developed for the spectrophotometric determination of pico-molar level of hydrazine using Alizarin red. There was a decrease of optical intensity of the probe in the presence of hydrazine. The LOD is calculated from the linear graph between 5-100 pM as 0.66 pM of hydrazine which is well below the risk level proposed by Agency for Toxic Substance and Disease Registry. The probe selectivity for the detection of hydrazine was tested in the presence of commonly encountered metal ions and anions. The calibration curves showed good linearity for working ranges from 5-100 pM and 0.5-40 mM respectively, with R(2)=0.9911 and 0.9744, indicate the validity of the Beer-Lambert law. The binding constant and the free energy change values are determined by the Benesi-Hildebrand method. Determination of hydrazine in environmental water and human urine samples are successfully performed by the proposed method with the recovery of 100%.

Facile preparation of Ni(OH)2-MnO2 hybrid material and its application in the electrocatalytic oxidation of hydrazine

A surfactant-free synthetic methodology is reported for the preparation of Ni(OH)2-MnO2 hybrid nanostructures. For comparative study, MnO2 and Ni(OH)2 were also synthesized. Materials were characterized by X-ray diffraction, nitrogen sorption, scanning electron microscopy, and transmission electron microscopy. Ni(OH)2-MnO2 modified electrode is fabricated for the determination of hydrazine. The electrochemical oxidation of hydrazine was investigated using cyclic, linear sweep voltammetries, and chronoamperometry methods. The Ni(OH)2-MnO2 modified electrode showed hydrazine oxidation with decrease in the over voltage and increase in the oxidation peak current, when compared to MnO2, Ni(OH)2, and bare GCE. pH was optimized to obtain the best peak potential and current sensitivity. Chronoamperometry was used to estimate the diffusion coefficient of hydrazine. The kinetic parameters such as overall number of electrons involved in the catalytic oxidation of hydrazine and the rate constant (k) for the oxidation of hydrazine at Ni(OH)2-MnO2 modified electrode were determined. The Ni(OH)2-MnO2 modified electrode exhibited good sensitivity, stability, and reproducibility in hydrazine sensing.

Carbon nanotubes and metalloporphyrins and metallophthalocyanines-based materials for electroanalysis

We discuss here the state of the art on hybrid materials made from single (SWCNT) or multi (MWCNT) walled carbon nanotubes and MN4complexes such as metalloporphyrins and metallophthalocyanines. The hybrid materials have been characterized by several methods such as cyclic voltammetry (CV), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM) and scanning electrochemical microscropy (SECM). The materials are employed for electrocatalysis of reactions such as oxygen and hydrogen peroxide reduction, nitric oxide oxidation, oxidation of thiols and other pollutants.