Showing papers by "S. Sriman Narayanan published in 2018"

Fabrication of carbon nanotube and synthesized Octadentate ligand modified electrode for determination of Hg (II) in Sea water and Lake water using square wave anodic stripping voltammetry

Abstract: Based on carbon nanotubes and N,N′,N″,N‴-Tetrasalicylidene-3,3′-diaminobenzidine (H4tsdb) modified electrode, the determination of Hg (II) ion using square wave anodic stripping voltammetry (SWASV) is reported. The N,N′,N″,N‴-Tetrasalicylidene-3,3′-diaminobenzidine (Octadentate ligand) has been derived from the condensation of Salicylaldehyde and 3′3-diaminobenzidine. The ligand has been characterized by Ultraviolet-Visible spectroscopy (UV-VIS), Fourier transform infrared spectroscopy (FT-IR) and Proton-Nuclear magnetic resonance (H1-NMR) spectroscopy. The surface morphology of the fabricated electrode has been characterized by scanning electron microscopy (SEM), electrochemical impedance spectroscopy (EIS). Operational parameters such as preconcentration, pH, supporting electrolytes were optimized for the determination of mercury (II) in 0.1 M NaNO3 pH 5. Under optimized condition, the electrochemical sensor exhibited a wider linear range from 2.4–220 nM and the limit of detection was 0.8 nM for Hg (II) (S/N ≤ 3). The relative standard deviation (RSD) was found to be 3.0% for five successive determinations. Interferences studies from other heavy metal ions such as Mn(II), Cd(II), Pb(II), Ni(II), Cu(II) and Zn(II) showed an insignificant effect on the electrochemical response of Hg(II) ion. The proposed electrode exhibited excellent performance in reproducibility, selectivity and also for successfully applied to analysis of Hg(II) in real environmental samples.

Fabrication of CdSe quantum dots @ nickel hexacyanoferrate core–shell nanoparticles modified electrode for the electrocatalytic oxidation of hydrazine

Abstract: We have reported an efficient method to immobilize the electroactive nickel hexacyanoferrate (NiHCF) on CdSe quantum dots (QDs). CdSe QDs @ NiHCF core–shell nanoparticles (NPs) were successfully synthesized and characterized using Fourier transform infrared spectroscopy and transmission electron microscopy. A simple, stable and reproducible CdSe QDs @ NiHCF NPs modified electrode has been constructed as a sensing platform for the electrochemical determination of hydrazine. The electrochemical behavior of CdSe QDs @ NiHCF NPs modified electrode was studied by cyclic voltammetry and electrochemical impedance spectroscopy. Under optimal condition the modified electrode exhibits well defined redox peaks at a formal potential of 0.31 V which corresponds to the redox reaction of hexacyanoferrate (II/III) of NiHCF. The sensor showed an enhanced electrocatalytic activity towards the oxidative determination of hydrazine in the concentration range of 1.6–1300 µM with the detection limit of 0.5 µM. The sensor has been tested for analysis of real samples, which makes it useful in practical area of environmental applications.

A novel sensor for the determination of Hg 2+ in waters based on octadentate ligand immobilized multi-walled carbon nanotube attached to paraffin wax impregnated graphite electrodes (PIGE)

Abstract: In this work, the synthesised octadentate ligand immobilised multi-walled carbon nanotubes (MWCNTs) modified electrode as an electrochemical sensor of Hg2+ is reported. The octadentate/MWCNTs composites were coated on the polished surface of paraffin impregnated graphite electrode for fabricating the enhanced electrochemical sensing platform for Hg2+ determination. The octadentate ligand contains four N and four O donor atoms which coordinate with the metal ion in stripping medium have been investigated. Surface morphology of the fabricated modified electrode was studied using scanning electron microscope (SEM). The modified electrode was characterised by electrochemical impedance spectroscopy (EIS) and square wave anodic stripping voltammetry (SWASV). Further various factors such as preconcentration time, effects of pH and different electrolytes were optimised for the detection of Hg2+. Under the optimised condition, anodic stripping voltammetry of Hg2+ showed a response in a linear range from 2.4 - 180 nM and the limit of detection was 0.8 nM for Hg2+ (S/N = 3). Interference studies with Cd2+,As3+,Cu2+, Ag+,Ni2+,Fe3+,Zn2+,Sn2+ and Pb2+ showed an insignificant effect on the electrochemical response of Hg2+. The proposed modified electrode exhibited an excellent performance with good reproducibility, selectivity and stability. The practical application of the modified electrode was also evaluated by the detection of Hg2+ in well water and lake water samples with good recovery results.

An Amperometric Sensor for the Determination of Dopamine Using Poly Zincon Film Modified Electrode

Abstract: Zincon, a metal ion indicator, has been polymerised on the graphite electrode to get a poly zincon film modified electrode. The formation of the polymer film (PZF)was confirmed by optical microscopis studies. The PZF modified electrode was characterised by the cyclic voltammetry, square wave voltammetry and chronoamperometry. The experimental parameters influencing the electrochemical behaviour of the PZF modified electrode such as pH and scan rates in presence of dopamine were optimised. The modified electrode showed excellent sensitivity and stability towards the electrocatalytic oxidation of dopamine. The determination range for dopamine was found to be 1.16 to 401μM with a correlation coefficient (R2) of 0.997. The limit of detection for the determination of Dopamine was 0.38 μM. The proposed method was used for the determination of dopamine in pharmaceutical preparations.

Understanding interaction of curcumin and metal ions on electrode surfaces using EDXRF

Abstract: A chemically modified electrode was developed for determination of metal ions (Cd, Pb, Zn, Co, Hg). The modifier used for the study was Curcumin. Curcumin acts as a complexing agent at the surface of the electrode for preconcentration of metal ions from electrolyte to electrode surface and stripped back to electrolyte during analysis. EDXRF was used to analyze these electrodes and it was concluded that the PCR modified electrode favored effective chelation for lead and mercury.A chemically modified electrode was developed for determination of metal ions (Cd, Pb, Zn, Co, Hg). The modifier used for the study was Curcumin. Curcumin acts as a complexing agent at the surface of the electrode for preconcentration of metal ions from electrolyte to electrode surface and stripped back to electrolyte during analysis. EDXRF was used to analyze these electrodes and it was concluded that the PCR modified electrode favored effective chelation for lead and mercury.