Amperometric Determination Of Hydrazine Research Articles

Electrocatalytic oxidation and amperometric determination of hydrazine using a carbon paste electrode modified with β-nickel hydroxide nanoplatelets.

β-Nickel hydroxide nanoplatelets (NPs) were synthesized and used as a modifier on a carbon paste electrode (CPE) for the detection of hydrazine. Synthesis is based on a one-step hydrothermal method using L-arginine that acts as an agent to adjust the pH value and to shape the NPs. They were characterized by field emission scanning electron microscopy, X-ray diffraction and energy-dispersive X-ray spectroscopy. The composition of the modified electrode was optimized by changing the amount of NPs. Best results were achieved using a 10:70:20 weight ratio for nanoparticles, graphite and mineral oil (the binder). The electrochemical properties of the modified CPE were studied by cyclic voltammetry. The surface coverage of the NPs, the electron transfer coefficient and the charge transfer rate constant were calculated. The diffusion coefficient of hydrazine is 1.56 × 10-5cm2s-1. An amperometric method was worked out that has the following figures of merit: (a) A working applied potential of 500mV (vs. Ag/AgCl reference electrode), (b) a linear range that extends from 1 to 1300μmolL-1, (c) a 0.28μmolL-1 detection limit, (d) a relative standard deviation of 1.3% (for n = 3 at a level of 5μmolL-1), and (d) a sensitivity of 1.33μAμmol-1Lcm-2. The performance of the sensor is compared to other nickel-based sensors for hydrazine. The sensor was successfully used to quantify hydrazine in spiked tap water samples, and the recoveries were 97 ± 2.3% (n = 3). Graphical abstract Schematic presentation of hydrazine electrocatalytic oxidation on NP.CPE*. *NP-CPE (β-nickel hydroxide nanoplatelet modified carbon paste electrode).

Sensitive and Rapid Flow Injection Amperometric Hydrazine Sensor using an Electrodeposited Gold Nanoparticle Graphite Pencil Electrode

A gold (Au) nanoparticle-modified graphite pencil electrode was prepared by an electrodeposition procedure for the sensitive and rapid flow injection amperometric determination of hydrazine (N2H4). The electrodeposited Au nanoparticles on the pretreated graphite pencil electrode surface were characterized by scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction spectroscopy, and electrochemical impedance spectroscopy. Cyclic voltammograms showed that the Au nanoparticle-modified pretreated graphite pencil electrode exhibits excellent electrocatalytic activity toward oxidation of hydrazine because the highly irreversibly and broadly observed oxidation peak at +600 mV at the pretreated graphite pencil electrode shifted to −167 mV at the Au nanoparticle pretreated graphite pencil electrode; in addition, a significant enhancement in the oxidation peak current was obtained. Thus, the flow-injection (FI) amperometric hydrazine sensor was constructed based on its electrocatalytic oxidation at the Au nanoparticle-modified pretreated graphite pencil electrode. The Au nanoparticle-modified pretreated graphite pencil electrode exhibits a linear calibration curve between the flow injection amperometric current and hydrazine concentration within the concentration range from 0.01 to 100 µM with a detection limit of 0.002 µM. The flow injection amperometric sensor has been successfully used for the determination of N2H4 in water samples with good accuracy and precision.

Highly stable and sensitive amperometric sensor for the determination of trace level hydrazine at cross linked pectin stabilized gold nanoparticles decorated graphene nanosheets

Herein, we have described a simple electrochemical method for the deposition of the calcium ions cross linked pectin film (CCLP) along with gold nanoparticles (GNPs) on the graphene (GR) modified glassy carbon electrode (GCE) and applied for the determination of hydrazine. The formation of composite film was confirmed by cyclic voltammetry, scanning electron microscopy, Energy-Dispersive X-ray spectroscopy and X-ray diffraction studies. The GR/CCLP-GNPs/GCE film exhibited significantly enhanced electro catalytic ability towards oxidation of hydrazine. The kinetic parameters such as electron transfer coefficient (α) and diffusion coefficient (Do) for the hydrazine oxidation were determined as 0.46 and 2.91×10−6 cm2 s−1, respectively. Two linear ranges were observed in the amperometric determination of hydrazine: (1) 10–600nM with sensitivity of 47.6 nAnM−1cm−2 and (2) 0.6–197.4μM with sensitivity of 1.786μAμM−1cm−2. The sensor is able to detect trace level of hydrazine in nanomolar range with very low deletion limit (LOD) of 1.6nM. This is the lowest LOD achieved compare to all the reported electrochemical amperometric sensors so far. In addition, the sensor is able to detect hydrazine even in the presence of 500 folds excess quantity of interfering ions present in the water and biological liquid. The practicality of the proposed sensor has been demonstrated in water and urine samples. Other advantages of the sensor are repeatability, reproducibility and stability.

Linen fiber template-assisted preparation of TiO2 nanotubes: palladium nanoparticle coating and electrochemical applications

TiO2 nanotubes were fabricated from TiF4 precursors within the pore channels of the linen fiber templates, resulting in crystalline fabricated titanate nanotubes (f-TNTs) upon removal by calcination at 500–600 °C. The f-TNTs were formed by the aggregation of TiO2 nanoparticles (NPs) with a diameter of 80 nm; the wall thickness and size of the f-TNTs can be controlled by adjusting the concentration of the TiF4 precursor, time, temperature, and the size of the linen fibers respectively. After that, palladium (Pd(0)) NPs were coated on the surface of the f-TNTs (Pd/f-TNTs) by the chemical reduction method, using NaBH4 as a reducing agent. The size of the Pd(0) NPs is about 10–13 nm. The Pd/f-TNT nanocomposite is systematically characterized by X-ray diffraction, high-resolution transmission electron microscopy, and field emission scanning electron microscopy. The Pd/f-TNT nanocomposite-modified glassy carbon electrodes exhibited excellent electrocatalytic activity as well as amperometric determination of hydrazine, ascorbic acid, and dopamine; these electrochemical applications were carried out by cyclic voltammetry.

Amperometric determination of hydrazine using a surface modified nickel hexacyanoferrate graphite electrode fabricated following a new approach

A new kind of modified electrode fabricated by attaching nickel hexacyanoferrate (NiHCF) to the surface of an amine-functionalized graphite is proposed. The cyclic voltammogram of the NiHCF modified electrode prepared by this method exhibits a pair of well defined redox peak at scan rates up to 200 mV s −1 in 0.1 M NaNO 3 (pH 7.0) solution. The effect of the supporting electrolyte indicates that the radius of the hydrated cation mainly determines the ion permeability of the film. The effect of the anions of the supporting electrolyte was also studied. The transfer coefficient (∞), and the electron transfer rate constant ( K s) were calculated in the presence of alkali metal cation. The modified electrode was characterized by electrochemical impedance spectroscopy (EIS) which showed that the tunable kinetic barrier was substantially altered by modifying the electrode with NiHCF. The modified electrode shows good electrocatalytic activity towards the electrochemical oxidation of hydrazine in 0.1 M NaNO 3 (pH 7.0). The oxidation current increased linearly with the concentration of hydrazine in the range of 2.4 × 10 −6–8.2 × 10 −3 M and with a correlation coefficient of 0.9976. The limit of detection was found to be 1 × 10 −6 M. The utility of the developed sensors in dynamic systems was evaluated by hydrodynamic and flow injection analysis (FIA). Differential pulse voltammetry (DPV) and flow injection analysis techniques were also used for determination of hydrazine from standard samples and different water sources chosen for real sample analysis (spiked with hydrazine). The developed sensor showed excellent stability for long time usage, higher sensitivity and was economical to fabricate.

Amperometric determination of hydrazine at manganese hexacyanoferrate modified graphite–wax composite electrode

Fabrication, characterization and application of a manganese hexacyanoferrate (MnHCF) modified graphite–wax composite electrode are described. The MnHCF mixed with graphite powder was dispersed into molten paraffin wax to yield a conductive composite, which was used as electrode material to construct a renewable three-dimensional MnHCF modified electrode. The characterization of the modified electrode has been studied by electrochemical techniques. The cyclic voltammogram of the MnHCF modified graphite–wax composite electrode prepared under optimum composition, showed a well-defined redox couple due to Fe(CN) 6 4−/Fe(CN) 6 3− system. The electrocatalytic oxidation of hydrazine by MnHCF modified graphite–wax composite electrode has been investigated in an attempt to develop a new sensor for its determination. It was found that the mediator catalyzed the oxidation of hydrazine. The electrocatalytic oxidation of hydrazine was also studied under hydrodynamic and chronoamperometric conditions. The anodic current increases linearly with increase in the concentration of hydrazine in the range of 3.33 × 10 −5 M to 8.18 × 10 −3 M. The detection limit was found to be 6.65 × 10 −6 M (S/N = 3). The modified electrode can also be used for on-line detection of hydrazine. The proposed method has also been applied for the determination of hydrazine in photographic developer solution.