We report herein a highly selective method for directly determining the trace Co^2+in highly concentrated zinc electrolyte.This novel method is based on a second derivative wave of catalytic adsorptive polarography ge...We report herein a highly selective method for directly determining the trace Co^2+in highly concentrated zinc electrolyte.This novel method is based on a second derivative wave of catalytic adsorptive polarography generated by complexing Co^2+with dimethylglyoxime and nitrite onto a dropping mercury electrode.By employing a medium with NH3-NH4Cl buffer,DMG and NaNO2 during determining the trace Co^2+,any interferences of highly concentrated Zn^2+and other coexisting metal ions in the electrolyte are completely eliminated due to the selective masking effect of EDTA.When the concentration of Co^2+is within 1.0×10^–10–3.2×10^–7 mol/L range,it shows a good linear relationship with the current peak.Detection limit is 1.0×10^–11 mol/L,and RSD≤2.7%for six successive assays.We have compared the efficiency of the current method to that obtained by cobalt nitroso-R-salt spectrophotometry,and the absolute values of relative deviations are≤4.2%.The method developed and described herein has been successfully employed in determining the trace Co2+in actual zinc electrolyte.展开更多
The novel covalently modified glassy carbon electrode with poly(xylitol) was prepared using an electropolymerization technique for the simultaneous determination of uric acid(UA), xanthine(XA) and hypoxanthine(HX). Th...The novel covalently modified glassy carbon electrode with poly(xylitol) was prepared using an electropolymerization technique for the simultaneous determination of uric acid(UA), xanthine(XA) and hypoxanthine(HX). This new electrode presents an excellent electrocatalytic activity towards the oxidation of UA, XA and HX by cyclic voltammetry(CV) method. The oxidation peaks of the three compounds were well defined and had enhanced the peak currents. The separation potentials of the oxidation peak potentials for UA-XA and XA-HX were 380 and 370 mV in CV, respectively. Using differential pulse voltammetry(DPV) method, the calibration curves in the ranges of 5-55, 1.3-75.3 and 4-59 μmol/L were obtained for HX, XA and UA, respectively. The lowest detection limits(S/N=3) were 4.5, 0.75 and 3.75 μmol/L for HX, XA and UA, respectively. The practical application of the modified electrode was demonstrated by the determination of UA, XA, HX in human urine samples.展开更多
The electrocatalytic oxidation of contraflam was investigated in alkaline solution on nickel and nickel–copper alloy modified glassy carbon electrodes(GC/Ni and GC/NiCu). We prepared these electrodes by galvanostatic...The electrocatalytic oxidation of contraflam was investigated in alkaline solution on nickel and nickel–copper alloy modified glassy carbon electrodes(GC/Ni and GC/NiCu). We prepared these electrodes by galvanostatic deposition and the surface morphologies and compositions of electrodes were determined by energy-dispersive X-ray(EDX) and scanning electron microscopy(SEM). Cyclic voltammetry and chronoamperometric methods were employed to characterize the oxidation process and its kinetics. Voltammetric studies exhibit one pair of well-defined redox peaks, which is ascribed to the redox process of the nickel and followed by the greatly enhanced current response of the anodic peak in the presence of contraflam and a decrease in the corresponding cathodic current peak. This indicates that the immobilized redox mediator on the electrode surface was oxidized contraflam via an electrocatalytic mechanism. The catalytic currents increased linearly with the concentration of contraflam in the range of 0.25– 1.5 mmol/L. The anodic peak currents were linearly proportional to the square root of scan rate. This behaviour is the characteristic of a diffusion-controlled process. The determination of contraflam in capsules is applied satisfactorily by modified electrode.展开更多
基金Projects(61533021,61773403)supported by the National Natural Science Foundation of China
文摘We report herein a highly selective method for directly determining the trace Co^2+in highly concentrated zinc electrolyte.This novel method is based on a second derivative wave of catalytic adsorptive polarography generated by complexing Co^2+with dimethylglyoxime and nitrite onto a dropping mercury electrode.By employing a medium with NH3-NH4Cl buffer,DMG and NaNO2 during determining the trace Co^2+,any interferences of highly concentrated Zn^2+and other coexisting metal ions in the electrolyte are completely eliminated due to the selective masking effect of EDTA.When the concentration of Co^2+is within 1.0×10^–10–3.2×10^–7 mol/L range,it shows a good linear relationship with the current peak.Detection limit is 1.0×10^–11 mol/L,and RSD≤2.7%for six successive assays.We have compared the efficiency of the current method to that obtained by cobalt nitroso-R-salt spectrophotometry,and the absolute values of relative deviations are≤4.2%.The method developed and described herein has been successfully employed in determining the trace Co2+in actual zinc electrolyte.
基金Project(201215135) supported by the Natural Science Foundation of Jilin Province,China
文摘The novel covalently modified glassy carbon electrode with poly(xylitol) was prepared using an electropolymerization technique for the simultaneous determination of uric acid(UA), xanthine(XA) and hypoxanthine(HX). This new electrode presents an excellent electrocatalytic activity towards the oxidation of UA, XA and HX by cyclic voltammetry(CV) method. The oxidation peaks of the three compounds were well defined and had enhanced the peak currents. The separation potentials of the oxidation peak potentials for UA-XA and XA-HX were 380 and 370 mV in CV, respectively. Using differential pulse voltammetry(DPV) method, the calibration curves in the ranges of 5-55, 1.3-75.3 and 4-59 μmol/L were obtained for HX, XA and UA, respectively. The lowest detection limits(S/N=3) were 4.5, 0.75 and 3.75 μmol/L for HX, XA and UA, respectively. The practical application of the modified electrode was demonstrated by the determination of UA, XA, HX in human urine samples.
基金financial assistance from Tehran University of Medical Sciences,Tehran,Iran
文摘The electrocatalytic oxidation of contraflam was investigated in alkaline solution on nickel and nickel–copper alloy modified glassy carbon electrodes(GC/Ni and GC/NiCu). We prepared these electrodes by galvanostatic deposition and the surface morphologies and compositions of electrodes were determined by energy-dispersive X-ray(EDX) and scanning electron microscopy(SEM). Cyclic voltammetry and chronoamperometric methods were employed to characterize the oxidation process and its kinetics. Voltammetric studies exhibit one pair of well-defined redox peaks, which is ascribed to the redox process of the nickel and followed by the greatly enhanced current response of the anodic peak in the presence of contraflam and a decrease in the corresponding cathodic current peak. This indicates that the immobilized redox mediator on the electrode surface was oxidized contraflam via an electrocatalytic mechanism. The catalytic currents increased linearly with the concentration of contraflam in the range of 0.25– 1.5 mmol/L. The anodic peak currents were linearly proportional to the square root of scan rate. This behaviour is the characteristic of a diffusion-controlled process. The determination of contraflam in capsules is applied satisfactorily by modified electrode.
