Simultaneous Determination Of Zn Research Articles

MnO2@Reduced Graphene Oxide Nanocomposite-Based Electrochemical Sensor for the Simultaneous Determination of Trace Cd(II), Zn(II) and Cu(II) in Water Samples.

The rapid detection of trace metals is one of the most important aspect in achieving environmental monitoring and protection. Electrochemical sensors remain a key solution for rapid detection of heavy metals in environmental water matrices. This paper reports the fabrication of an electrochemical sensor obtained by the simultaneous electrodeposition of MnO2 nanoparticles and RGO nanosheets on the surface of a glassy carbon electrode. The successful electrodeposition was confirmed by the enhanced current response on the cyclic voltammograms. The XRD, HR-SEM/EDX, TEM, FTIR, and BET characterization confirmed the successful synthesis of MnO2 nanoparticles, RGO nanosheets, and MnO2@RGO nanocomposite. The electrochemical studies results revealed that MnO2@RGO@GCE nanocomposite considerably improved the current response on the detection of Zn(II), Cd(II) and Cu(II) ions in surface water. These remarkable improvements were due to the interaction between MnO2 nanomaterials and RGO nanosheets. Moreover, the modified sensor electrode portrayed high sensitivity, reproducibility, and stability on the simultaneous determination of Zn(II), Cd(II), and Cu(II) ions. The detection limits of (S/N = 3) ranged from 0.002–0.015 μg L−1 for the simultaneous detection of Zn(II), Cd(II), and Cu(II) ions. The results show that MnO2@RGO nanocomposite can be successfully used for the early detection of heavy metals with higher sensitivity in water sample analysis.

Macroporous Graphene Thin Films as Electrochemical Electrodes: Enhancing the Sensitivity for Detection of Metal Ions

A macroporous graphene thin films coated on ITO substrates (MGTFs@ITO) have been developed as electrodes for the electrochemical detection of heavy metal ions. The MGTF@ITO electrodes were characterized by scanning electron microscopy, Raman spectroscopy and contact angle measurements. The results demonstrated that the MGTF@ITO has a high specific area with robust macroporous framework and a hydrophilic surface. The cyclic voltammetry and electrochemical impedance spectroscopy using MGTFs@ITO as electrochemical electrodes indicated enhanced currents at the redox peaks, enlarged electrochemical surface area and a decreased charge transfer resistance. Based on these outstanding properties, the MGTF@ITO electrodes exhibited excellent stripping performace for the analysis of Ag(I) with a detection limit of 0.005 μg L-1. The high sensitivity of the MGTF@ITO electrodes can be ascribed to the well defined macroporous framework, high electrical conductivity, high specific area and good wettability. The MGTF@ITO electrodes were further demonstrated applicable to the simultaneous determination of Zn(II), Cd(II), Pb(II), Cu(II) and Ag(I) ions with outstanding sensing performance.

Simultaneous determination of Zn, Cd, Pb and Cu in mushrooms by differential pulse anodic stripping voltammetry

Simultaneous determination of Zn, Cd, Pb and Cu in mushrooms by differential pulse anodic stripping voltammetry

Use of pyrolyzed paper as disposable substrates for voltammetric determination of trace metals

The possibility of using pyrolyzed paper as disposable working electrodes for trace metals determination is reported for the first time. A small piece of pyrolyzed paper (0.7×0.7cm) was positioned at the bottom side of the electrochemical cell using a rubber O-ring, which defined the electrode area (0.48cm; 0.18cm2). A large number of electrodes can be obtained from a single piece of standard dimensions (2.5cm×7.5cm) of paper, therefore minimizing the cost per unit. The electrochemical performance of the pyrolyzed paper was demonstrated by cyclic voltammetry, electrochemical impedance spectroscopy and by the determination of Zn, Cd, and Pb by square-wave anodic stripping voltammetry. The unmodified pyrolyzed paper showed excellent performance for Pb and Cd detection (LOD =0.19 and 0.16 ppb, respectively). In the presence of Bi3+(in-situ film formation), the simultaneous determination of Zn, Cd and Pb was also possible (LOD=0.26, 0.25, and 0.39 ppb, respectively).

Systematic evaluation of sample preparation method for simultaneous voltammetric determination of Zn, Cd, Pb, and Cu in macroalgae

In this paper, four mineralization procedures of macroalgae were evaluated. Two methods used a closed system microwave) and two an open system (strong acid and ultraviolet radiation). Zn, Cd, Pb, and Cu were determined by square-wave anodic stripping voltammetry (SWASV) and graphite furnace atomic absorption spectrometry (GF AAS) was used as comparative method. Determinations of total, inorganic, and organic carbon, as well as the study of matrix effect, were performed. It could be observed that, although mineralizations accomplished with open systems presented lower levels of total carbon and lower matrix effect, the determinations of compounds from standard reference material (SRM) did not show acceptable recoveries. However, the mineralization using microwave (closed system—methods A and B) showed recovery within the acceptable range to all compounds (78 to 115 %), and after statistical analysis, it can be concluded that the method A is more accurate than the method B; therefore, most suitable for macroalgae mineralization and simultaneous determination of Zn, Cd, Pb, and Cu by voltammetry.

A pencil-lead bismuth film electrode and chemometric tools for simultaneous determination of heavy metals in propolis samples

A simultaneous determination of Zn, Cd, Pb and Cu in raw propolis samples, employing square wave anodic stripping voltammetry and chemometric tools, was developed. For this purpose, a pencil-lead bismuth film electrode was used as a working electrode. In order to optimize the parameters of square wave voltammetry a Box–Behnken design combined with desirability function was used. Different algorithms such Asymmetric Least Squares (AsLS) and Correlation Optimized Warping (COW) were employed in order to preprocess the raw data. Partial Least Squares (PLS) and Artificial Neuron Networks (ANN) were used to predict the concentration of the four metals in the samples. The method was tested successfully on raw propolis samples obtained from different localities of the Province of Buenos Aires, Argentina and the results were validated with recovery assays.

Simultaneous determination of Zn, Cd, Pb, and Cu in urine of patients with blackfoot disease using anodic stripping voltammetry.

Blackfoot disease (BFD) is an endemic peripheral vascular disorder resulting in gangrene of the lower extremities, especially the feet, among residents in a limited area on the southwest coast of Taiwan. In the present study, the concentrations of zinc, cadmium, lead, and copper in urine of BFD patients with matched normal controls are investigated by differential pulse anodic stripping voltammetry (DPASV) on a hanging mercury drop electrode (HMDE). The analytical results indicate that urinary copper, cadmium, and lead of the BFD patients are significantly higher than those of the controls. In addition, the patients showed a significantly lower concentration of zinc in the urine than the normal controls. The possible connection of these elements with the etiology of the disease is discussed.

Polarographic determination of Zn(II), Ni(II) and Co(II) in the presence of polyethylene glycol

The difference in the half-wave potentials of Zn(II) and Ni(II), whose reduction potentials are close to each other, becomes larger in the presence of polyethylene glycol. The relationship between the concentration of the ions and their wave currents was linear for both ions in the presence of this polymer, suggesting that the simultaneous determination of Zn(II) and Ni(II) is possible.

Simultaneous determination of Zn(II) and Ni(II) in the presence of crown ether by dc polarography

The simultaneous determination of Zn(II) and Ni(II) was studied in the presence of a crown ether by dc polarography. Addition of this reagent caused the difference in the halfwave potentials between the two ions to increase from 0.01 to 0.34 V. The relationship between the concentration of the ion and the wave current was linear for both ions, which suggests the feasibility of a simultaneous determination of Zn(II) and Ni(II) in the presence of a crown ether.

The simultaneous determination of Fe(III) and Cu(II) in the presence of Zn(II) using 2-(5-bromo-2-pyridylazo)-5-(diethylamino)phenol

Spectrophotometric methods were employed to study the chelate formation between Fe(III) ions and 2-(5-bromo-2-pyridylazo)-5-(diethylamino)phenol (BrPADAP) in dimethylformamide (φ = 20%) and Triton X-100 (φ = 0·1%). The ML2 chelate with absorption maxima at 535 and 590 nm and molar absorption coefficients of 6·5 and 8·2 m2 mmol-1 is formed quantitatively in the pH interval 3·5 - 4·0 for at least a seven-fold concentration excess of BrPADAP. Concentrations of c(Fe) = 1·6 - 8·1 μmol l-1 can be determined independently in 0·1M acetate buffer with pH 3·6. Iron and copper ions can be determined simultaneously in the presence of zinc ions in binary or ternary mixtures in the concentration ranges c(Fe) = 2 - 8 μmol l-1 and c(Cu) = c(Zn) = 3 - 16 μmol l-1. The relative deviations in the calculated concentrations, Δcr, are 1 - 4% for Fe and up to 5% for Cu in binary and ternary mixtures with equivalent concentrations up to a concentration excess of one component of five-fold in binary mixtures or of one or two components of up to three-fold in ternary mixtures. The simultaneous determination of Zn(II) is accompanied by a Δcr value of up to 30 - 50% and cannot be recommended under the given experimental conditions.

Direct and simultaneous determinations of Zn, Cd, Pb, Cu, Sb and Bi dissolved in sea water by differential pulse anodic stripping voltammetry with a hanging mercury drop electrode

Differential pulse anodic stripping voltammetry with a hanging mercury drop electrode is used for the direct and simultaneous determination of Zn, Cd, Pb, Cu, Sb and Bi at their natural levels in sea water after adjustment to pH 1 and to a 2 M chloride concentration. The optimal instrumental parameters are described. With a plating time of 60 min, the detection limits are about 0.1 ppb for Zn and Cu, 0.01 ppb for Cd and Pb, and 0.05 ppb for Sb and Bi. Relative standard deviations are about 10—15%. Simultaneous determinations of the six metals take about 2 h.

Simple and precise determination of Zn and Cd in human liver by neutron activation analysis

A simple neutron activation method for the simultaneous determination of Zn and Cd in biological tissue is described. After HNO3/H2SO4 digestion of the irradiated samples, a one-step anion exchange separation is used for the isolation of 65Zn and 115Cd with about 98% chemical yield. The precision from duplicate analyses of human liver is 3–4% for Zn in the concentration range of 20–120 ppm and about 5% for Cd in the 1-ppm region.