Zinc oxide nanonail based chemical sensor for hydrazine detection

Reduced graphene sheets modified glassy carbon electrode for electrocatalytic oxidation of hydrazine in alkaline media

Palladium nanoparticle decorated carbon ionic liquid electrode for highly efficient electrocatalytic oxidation and determination of hydrazine.

This review describes recent results regarding voltammetric and amperometric determination of submicromolar concentrations of various environmentally important biologically active organic substances using nontraditional types of electrodes either in batch analysis or in flow liquid systems (especially HPLC or FIA with electrochemical detection). Attention is paid to solid amalgam electrodes (environmentally friendly alternatives to mercury electrodes), to carbon paste electrodes with easily renewable surface, to boron doped diamond film electrodes with very low noise and broad potential window, and to inexpensive solid composite electrodes with high signal-to-noise ratio, compatibility with organic solvents and easy mechanical or electrochemical pretreatment. The review concentrates on our own results in the context of the general development in the filed.

Nontraditional Electrode Materials in Environmental Analysis of Biologically Active Organic Compounds

Synthesis of reduced graphene oxide (RGO) from graphite oxide (GO) usually involves the use of some harmful reducing agents. Here, we report a simple approach for the reduction of GO at room temperature using a mixture of potassium iodide and hydrochloric acid. The reduction of GO involves (a) iodide mediated epoxide ring-opening, resulting in hydroxyl groups and dehydration to the corresponding olefins, (b) hydroxyl group substitution by iodide ions, and (c) elimination of iodide ions on the surface. The as-synthesized RGO has an electrical conductivity of 1251 S m−1 and an excellent electrocatalytic activity. The electrocatalytic activity of RGO towards the electrochemical reduction of oxygen and the oxidation of hydrazine was investigated. The RGO-based electrode showed pronounced electrocatalytic activity towards the reduction of oxygen and the oxidation of hydrazine in 0.1 M KOH. At alkaline pH, the reduction of oxygen and oxidation of hydrazine were observed at −0.35 and 0.5 V, respectively. In comparison with the bare glassy carbon (GC) electrode, a spectacular decrease in the overpotential and considerable increase in the oxidation peak current for hydrazine were observed on the RGO-based electrode without using any redox mediator. The RGO-based platform is highly sensitive towards the electrochemical oxidation of hydrazine and reproducible results were obtained. Moreover, the RGO-based electrode showed excellent operational and long time storage stabilities. The sensitivity of the electrode was calculated to be 0.137 ± 0.02 μA mM−1.

Iodide-mediated room temperature reduction of graphene oxide: a rapid chemical route for the synthesis of a bifunctional electrocatalyst

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

A graphite–wax composite electrode chemically modified with silver hexacyanoferrate (AgHCF) as a redox mediator was fabricated. Cyclic voltammetry was used to study the redox property of the AgHCF modified graphite–wax composite electrode. Various experimental parameters influencing the electrochemical behavior of the modified electrode were optimized by varying the background electrolytes, scan rates and pH. The electrochemical rugosity of the modified electrode at various scan rates was calculated from the anodic wave of the cyclic voltammogram. The feasibility of using the AgHCF modified electrode to measure butylated hydroxyanisole (BHA) was investigated. The modified electrode showed an excellent electrocatalytic activity towards the oxidation of BHA in 0.1 M KNO 3 at pH 6. The analytical utility of the electrode as an amperometric sensor for the determination of BHA in a flow system was evaluated by carrying out hydrodynamic and chronoamperometric studies. Under optimized conditions amperograms were recorded and it was found that the oxidation current increased linearly with successive addition of BHA in the concentration range of 7.4 × 10 −6 –8.3 × 10 −4  M. The limit of detection was found to be 3.7 × 10 −6  M. For 10 successive determination of BHA at a concentration of 1.79 × 10 −4  M, the relative standard deviation (R.S.D.) was 1.3%. The electrode showed a good electrochemical response in terms of sensitivity, stability and reproducibility. The proposed sensor was applied to the determination of BHA in spiked samples of dehydrated potato flakes.

D. Jayasri

Papers

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

Electrocatalytic oxidation and amperometric determination of BHA at graphite–wax composite electrode with silver hexacyanoferrate as electrocatalyst

Manganese(II) hexacyanoferrate based renewable amperometric sensor for the determination of butylated hydroxyanisole in food products