• Journal of Biosystems Engineering
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• v.33 no.6
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• pp.404-409
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• 2008

Excessive presence of heavy metals in environment affects plants and fruits grown in the contaminated area. Rapid on-site monitoring of heavy metals can provide useful information for efficiently characterizing heavy metal-contaminated sites and for minimizing the exposure of the contaminated food crops to humans. This study reports on the evaluation of gold and glassy carbon (GC) electrodes with mercury or bismuth as a coating material for simultaneous determination of cadmium (Cd) and lead (Pb) in 0.1 M $HNO_3$ solution by anodic stripping voltammetry (ASV). The use of a square-wave voltammetric potential between a working electrode and a reference electrode caused Cd and Pb ions deposited on the electrode surface to be oxidized, thereby generating electric currents at different potentials. The mercury-coated gold electrode was not sensitive enough to detect the usable range of Cd concentrations (1 to 100 ppb). The GC electrodes with mercury or bismuth displayed well-defined, sharp and separate current peaks for Cd and Pb ions when the square-wave voltammetric potentials were applied. The peak currents measured with both mercury- and bismuth- coated GC electrodes were linearly proportional to Cd and Pb concentrations in the range of 1 to 200 ppb in 0.1 M $HNO_3$ with strong linear relationships between concentration and peak current ($R^2$ > 0.95), indicating that both of Cd and Pb ions could be quantitatively measured.

• Journal of Powder Materials
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• v.15 no.5
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• pp.393-398
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• 2008

Trace analysis of Cd and Pb at surface modified thick film graphite electrode with Bi nanopowder has been carried out using square-wave anodic stripping voltammetry (SWASV) technique. Bi nanopowder synthesized by gas condensation (GC) method showed the size of $50{\sim}100$ nm with BET surface area, $A_{BET}=6.8m^{2}g^{-l}$. For a strong adhesion of the Bi nanopowder onto the screen printed carbon paste electrode, nafion solution was added into Bi-containing suspension. From the SWASV, it was found that the Bi nanopowder electrode exhibited a well-defined responses relating to the oxidations of Cd and Pb. The current peak intensity increased with increasing concentration of Cd and Pb. From the linear relationship between Cd/Pb concentrations and peak current, the sensitivity of the Bi nanopowder electrode was quantitatively estimated. The detection limit of the electrode was estimated to be $0.15{\mu}g/l$ and $0.07{\mu}g/l$ for Cd and Pb, respectively, on the basis of the signal-to-noise characteristics (S/N=3) of the response for the $1.0{\mu}g/l$ solution under a 10 min accumulation.

• Journal of the Korean Chemical Society
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• v.37 no.5
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• pp.477-482
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• 1993

The determination of trace level mercury in bio-materials has been investigated by the square wave anodic stripping voltammetry (ASV)-technique at glassy carbon electrode. Prior to analysis, the bio-materials were digested with HNO3/H2SO4 mixture and KMnO4 was added to complete the oxidation. The detection limit of the mercury varied greatly with deposition time, deposition potential, pH and stirring rate. When deposition is carried out for 240 sec with 400 rpm stirring at -1.0 volts vs. Ag/AgCl, the detection limit was below $0.5\;ppb\;(2.5{\times}10^{-9} M)$. The method is recommended for trace level mercury analysis of biomaterials because this procedure is time saving and has higher sensitivity.

• Bulletin of the Korean Chemical Society
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• v.34 no.9
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• pp.2577-2582
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• 2013

A novel stick-shaped portable sensing device featuring a microhole array interface between the polyvinylchloride-2-nitrophenyloctylether (PVC-NPOE) gel and water phase was developed for in-situ sensing of perchlorate ions in real water samples. Perchlorate sensitive sensing responses were obtained based on measuring the current changes with respect to the assisted transfer reaction of perchlorate ions by a perchlorate selective ligand namely, bis(dibenzoylmethanato)Ni(II) (Ni(DBM)2) across the polarized microhole array interface. Cyclic voltammetry was used to characterize the assisted transfer reaction of perchlorate ions by the $Ni(DBM)_2$ ligand when using the portable sensing device. The current response for the transfer of perchlorate anions by $Ni(DBM)_2$ across the micro-water/gel interface linearly increased as a function of the perchlorate ion concentration. The technique of differential pulse stripping voltammetry was also utilized to improve the sensitivity of the perchlorate anion detection down to 10 ppb. This was acquired by preconcentrating perchlorate anions in the gel layer by means of holding the ion transfer potential at 0 mV (vs. Ag/AgCl) for 30 s followed by stripping the complexed perchlorate ion with the ligand. The effect of various potential interfering anions on the perchlorate sensor was also investigated and showed an excellent selectivity over $Br^-$, $NO_2{^-}$, $NO_3{^-}$, $CO{_3}^{2^-}$, $CH_3COO^-$ and $SO{_4}^{2^-}$ ions. As a final demonstration, some regional water samples from the Sincheon river in Daegu city were analyzed and the data was verified with that of ion chromatography (IC) analysis from one of the Korean-certified water quality evaluation centers.

• Analytical Science and Technology
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• v.7 no.2
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• pp.141-147
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• 1994

The adsorptive stripping voltammetry of corticosterone was studied in $1.0{\times}10^{-2}M$ sodium hydroxide as supporting electrolyte. The analytical conditions were as follow : 360 sec. for deposition time, -8.0 volts deposition potential, medium size mercury drop, and 20mV/sec scan rate. Calibration curve has shown a linearlity in the range of $5.0{\times}10^{-9}M$ to $8.0{\times}10^{-7}M$ and the detection limits have been $9.5{\times}10^{-10}M$ for corticoterones. This method has shown such a high sensitivity even in dilute solution that has been useful for analyzing sex hormones in medical supplies without interference of additives.

• Journal of the Korean Chemical Society
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• v.45 no.4
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• pp.298-303
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• 2001

The trace-level mercury in bio-materials has been determinated by the anodic stripping square wave voltammetry (ASSWV)-technique at glassy carbon electrode. Prior to the analysis, the bio-materials were digested with $HNO_3/H_2SO_4$ mixture and KMnO4 was added to complete an oxidation process of the mixture. The detection limit of the mercury varied greatly with deposition time, deposition potential, pH and stirring rate. When the deposition was carried out for 240 sec on 400 rpm stirring at -1.0 volts vs. Ag/AgCl, the detection limit was below 0.5 ppb ($2.5{\times}10^{-9}M$). The accumulated mercury was high in the kidney and liver, and low in the brain according to the determination of mercury accumulation for a white rat by this method.

• Journal of the Korean Chemical Society
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• v.37 no.11
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• pp.943-950
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• 1993

The determination of trace level germanium in 5.0 ${\times}\;10^{-2}$ M perchloric acid supporting electrolyte solution containing 8.0 ${\times}\;10^{-2}$ M catechol has been investigated by the square wave anodic stripping voltammetry. The optimum conditions in determination of germanium were as follows: deposition time; 120 sec, deposition potential; -0.9 volts vs. Ag/AgCl and frequency; 100 Hz. The determination of germanium was possible regardless of coexistent ion such as copper, lead and silicon. Calibration curve was shown a good linearlity in the range of 0.40 ppb to 2.0 ppm and the detection limit was 0.080 ppb. This method was useful for trace level germanium due to the short analysis time and higher sensitivity.

• Analytical Science and Technology
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• v.8 no.4
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• pp.611-615
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• 1995

The design of appropriate chemically modified electrodes should allow development of new voltammetric measurement schemes with enhanced selectivity and sensitivity. Microorganism like algae has high ability to trap toxic and heavy metal ions and different affinities for metal ions. A copper(II) ion-selective carbon paste electrode was constructed by incorporating alga Anabaena into a conventional carbon paste mixture, and then the film of 10% Nafion was coated to avoid the swelling of the electrode surface. Copper ion could be deposited at the 25% algamodified electrode for 15 min without the applied potential while stirring the solution by only immersing the electrode in a buffer (pH 4.0) cot1taining copper(II). Temperature was controlled at $35^{\circ}C$. After preconcentration was carried out the electrode was transferred to a 0.1 M potassium chloride solution and was reduced at -0.6 volt at $25^{\circ}C$. The differential pulse anodic stripping voltammetry was employed. A well-defined oxidation peak could be obtained at -0.1 volt (vs SCE). In five deposition / measurement / regeneration cycles, the responses were reproducible and relative standard deviations were 3.3% for $8.0{\times}10^{-4}M$ copper(II). Calibration curve for copper was linear over the range from $2.0{\times}10^{-4}M$ to $1.0{\times}10^{-3}M$. The detection limit was $7.5{\times}10^{-5}M$. Studies of the effect of diverse ions showed that the coexisting metal ions had little or no effect for the determination of copper. But anions such as cyanide. oxalate and EDTA seriously interfered.

• Journal of the Korean Chemical Society
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• v.38 no.2
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• pp.146-150
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• 1994

The simultaneous determination of Zn, Cd, Pb and Cu in 1.000%(w/v) tungsten matrix by differential pulse anodic stripping voltammetry at a hanging mercury drop electrode has been studied. Tartaric acid(pH=5.00) was used as a supporting electrolyte. Optimum analytical conditions were found that the deposition potential was -1.2 volt(vs. Ag/AgCl), the deposition time was 3 minutes. The linear concentration range of all trace metal ions in 1.000%(w/v) tungsten matrix were 10 to 50 ppb. And the detection limit(3${\sigma}$) of zinc, cadmium, lead and copper were 1.25, 1.02, 1.69, and 1.02 ppb respectively. This method was superior to the ICP-AES method which detection limits(3${\sigma}$) in 1.000%(w/v) tungsten matrix were 8.0, 5.0, 120 and 5 ppb respectively.

• Journal of the Korean Chemical Society
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• v.50 no.3
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• pp.208-215
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• 2006

A simply prepared graphite, pencil-type working electrode was utilized to monitor fenitrothion concentrations, using the cyclic voltammetry (CV) and square-wave (SW) stripping voltammetry methods. The optimum conditions for analysis were sought. A very low detection limit was obtained compared to that obtained when other common voltammetry methods are used. The optimal parameters of the pencil-type electrode were found to be as follows: a pH of 3.7, a frequency of 500 Hz, an SW amplitude of 0.1 V, an increment potential of 0.005 V, an initial potential of -0.9V, and a deposition time of 500 sec. The analytical detection limit was determined to be 6.0 ngL-1 (2.16410-11 molL-1) fenitrothion at SW anodic and CV, and the relative standard deviation at the fenitrothion concentration of SW anodic 10 ugL-1 was 0.30% (n = 15) under the optimum conditions. Analysis was directly conducted through in-vivo real-time assay.