Chemically functionalized glassy carbon spheres: A new covalent bulk modified composite electrode for the simultaneous determination of lead and cadmium

A new type of covalent bulk modified glassy carbon composite electrode has been fabricated and utilized in the simultaneous determination of lead and cadmium ions in aqueous medium. The covalent bulk modification was achieved by the chemical reduction of 2-hydroxybenzoic acid diazonium tetrafluroborate in the presence of hypophosphorous acid as a chemical reducing agent. The covalent attachment of the modifier molecule was examined by studying Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy and the surface morphology was examined by scanning electron microscopy images. The electrochemistry of modified glassy carbon spheres was studied by its cyclic voltammetry to decipher the complexing ability of the modifier molecules towards Pb 2+ and Cd 2+ ions. The developed sensor showed a linear response in the concentration range 1-10 μM with a detection limit of 0.18 and 0.20 μM for lead and cadmium, respectively. The applicability of the proposed sensor has been checked by measuring the lead and cadmium levels quantitatively from sewage water and battery effluent samples

Designing of Au doped TiO2 NPs as an electrocatalyst for nitrite sensor

In the present work, a simple ionothermal protocol for the synthesis of Au doped TiO2 and its subsequent application as an electrochemical interface for the trace level electroanalytical quantification of nitrite ion has been described. The surface morphology and the composition has been described with the help of Scanning electron microscope and Energy Dispersive X-Ray techniques. Further, it has been used in the fabrication of thin film electrodes by a simple physical drop casting method. Cyclic voltammetry has been used to decipher the electrocatalytic property of the modified interface towards nitrite ions and square wave voltammetry to work in the low concentration levels of nitrite ions. The developed sensor interface revealed superior nitrite sensing performance in the dynamic concentration range from 3.3 to 120 µM with a very low experimental detection limit of 0.095 µM with a sensitivity of 0.9973. The analytical applicability of the developed interference has been validated by determining the presence of nitrite from real samples with least interference from commonly encountered foreign ions. The stability and reproducibility of the proposed interface has been studied over a period of several months and the results were found to be highly reproducible with a relative standard deviation of ± 5 %. These results show that, the proposed interface electrode display better electrocatalytic activity compared to the previously reported sensors for the electro oxidation of nitrite ions