H. Jayadevappa

ZnO and ZnO/polyglycine modified carbon paste electrode for electrochemical investigation of dopamine

Present work describes the characterization of commercially available ZnO and its electrochemical investigation of dopamine in the presence of ascorbic acid. ZnO was characterized by powder XRD, UV-visible absorption, fluorescence, infrared spectroscopy and scanning electron microscopy. The carbon paste electrode was modified with ZnO and ZnO/polyglycine for further electrochemical investigation of dopamine. The modified electrode shows good electrocatalytic activity towards the detection of dopamine with a reduction in overpotential. The ZnO/polyglycine modified carbon paste electrode (CPE/ZnO/Pgl) shows excellent electrochemical enhancement of peak currents for both dopamine (DA) and ascorbic acid (AA) and for simultaneous detection of DA in the presence of high concentrations of AA with 0.214 V oxidation peak potential differences between them at pH 7.4. From the scan rate variation and concentration, the oxidation of DA and AA was found to be adsorption-controlled. The use of CPE/ZnO/Pgl is demonstrated for the detection of DA in blood serum and injection samples.

Synthesis of MgFe2O4 nanoparticles and MgFe2O4 nanoparticles/CPE for electrochemical investigation of dopamine

Magnesium ferrite nanoparticles (MgFe2O4 NPs) were prepared by a solution based method using magnesium sulphate (MgSO4), ferrous sulphate (FeSO4), dl serine and NaOH as a precipitant and the obtained precipitation was calcinated under 500 °C for 4 h. The resulting material was characterized by using X-ray diffractometry (XRD) and scanning electron microscopy (SEM). The MgFe2O4 NPs were used for preparation of MgFe2O4 NPs/carbon paste electrode (MgFe2O4 NPs/CPE) and applied for electrochemical investigation of dopamine (DA) which exhibits good electrocatalytic activity for investigation of DA at physiological pH 7.4. The effect of pH range from 5.5 to 8.0 was studied and the result shows that the redox peak current was maxima at pH 7.5 and the redox peak was pH dependent with a slope of 0.061 V/pH. The scan rate effect was found to be an adsorption-controlling electrode process. The electrocatalytic currents increased linearly with an increase in DA concentration in the range 0.1–1.2 μM and the detection limit was found to be 7.7 × 10−8 M. The proposed method was successfully applied to the determination of DA in injection samples.

Electrochemical Investigation of Paracetamol at Poly(Glycine) ModifiedCarbon Paste Electrode: A Voltametric Study

The carbon paste electrode was modified by electropolymerisation of 1 mM Glycine in 0.2 M Acetate buffer solution (ABS) at pH-5. The voltammetric response of Paracetamol (PA) at Poly(Glycine) Modified carbon paste electrode (MCPE) shows excellent electrocatalytic activity when compared to bare carbon paste electrode (BCPE) at sweep rate of 100 mV/s-1. From the study of scan rate variation the electrode process was found to be diffusion controlled. The concentration effect of paracetamol was studied. The simulations determination of PA, DA and AA in their sample mixture was analyzed by using both cyclic voltammetric and differential pulse voltammetric techniques.

Nanorod TiO2 sensor for dopamine: a voltammetric study

Nanorod shaped titanium oxide (TiO2NRs) was synthesized by the hydrothermal process in 10 M NaOH(aq.) at 120 °C. The TiO2NRs were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), infrared spectroscopy (IR) and UV-visible absorption spectroscopy (UV-vis). An electrochemical sensor for the responsive determination of dopamine (DA) was evolved by designing a carbon paste electrode (CPE) modified with titanium oxide nanorods (TiO2NRs/MCPE). The modification of the TiO2NRs using different surfactants like sodium dodecyl sulphate (SDS), cetyltrimethylammonium bromide (CTAB) and polyglycine failed to produce an impressive charge transfer and the resulting electrodes were also less sensitive for the determination of DA. However, modification with iso-octyl phenoxy polyethoxy ethanol (TX-100) improved the redox property of DA, with increased current intensity on the surface of the TiO2NRs/MCPE, showed good electrocatalytic properties and also produced an enhancement in the peak currents for DA (TiO2NRs/TX-100/MCPE). The detection limit of DA was determined from a differential pulse voltammetric (DPV) study and was found to be 42 × 10−9 M. The effect of concentration, scan rate and pH of DA was studied and a simultaneous determination of dopamine (DA), uric acid (UA), ascorbic acid (AA) and paracetamol (PA) using the TiO2NRs/TX-100/MCPE was carried out. The interference studies showed that the modified electrode exhibits excellent selectivity in the presence of a large excess of interferents and the response is fast, stable and can be applied for real sample analysis in medical, biotechnological and pharmaceutical fields.

Electropolymerized Congo Red Film based Sensor for Dopamine: A Voltammetric Study

The polymerization film of Congo red was prepared on the surface of carbon paste electrode by electropolymerization using cyclic voltammetric method. The higher catalytic activity was obtained for electrocatalytic oxidation of Dopamine, with drastic enhancement of the reversibility and peak current in 0.2 phosphate buffer solution of pH 7.0 at the sweep rate 100 mV/s. The variation of sweep rate and pH were investigated. The limit of detection of Dopamine was found to be 0.06 μM. The effect of interference studies was done by differential pulse voltammetric technique. In the simultaneous look at, Dopamine and Uric acid were well separated by cyclic voltammetric technique. The proposed method showed good sensitivity, selectivity, and reproducibility.

Electrochemical Studies of Paracetamoland Folic Acid in the Presence ofEpinephrineat Poly (Eosin) Modified Electrode: A Voltammetric Study

In this work, Poly eosin modified carbon paste electrode was prepared by electropolymerisation method by using cyclic voltammetry technique. This poly (Eosin) modified CPE exhibited an excellent electrocatalytic activity towards the oxidation PA and FA in presence of EP in 0.2M PBS at pH 7.0. The effect of pH and sweep rate was studied. The limit of detection of PA and FA were found to be 0.06 and 0.04 μM, respectively. An electrochemical simultaneous separation was observed in a binary mixture containing PA, FA and EP and interference study was done by differential pulse voltammetry technique. Finally, the prepared fabricated sensor exhibits good sensitivity, and selectivity.