• YAKHAK HOEJI
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• v.29 no.3
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• pp.144-151
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• 1985

Cathodic stripping voltammetric determination of traces of selenium in plant samples was studied. Stripping peak of selenium (IV) from Cu-Se intermettalic deposit in acidic media containing copper (II) ion is specific, highly sensitive and well defined, is successfully used for the quantitative determination of selenuin down to the level of 1ng/ml. Sample is burnt in a calorimeter bomb under the oxygen pressure of 40atm. and the selenium is absorbed in 0.1M NaOH. After the solution is filtrated, concentrated and acidified with HCl, then passed through a column of cation exchange resin in the $H^{+}$ form(Dowex 50X-8). The column eluate is analyzed for selenium by differential pulse cathodic stripping voltammetric method. Analytical results of selenium for NBS SMR is well agreement with the certified values. Results are given for a series of plant materials.

• Journal of the Korean Electrochemical Society
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• v.7 no.1
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• pp.9-15
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• 2004

Cyclic voltammetry and chronocoulometry have been used for characterization of catechol violet (CV) at the hanging mercury drop electrode in acetic acid-sodium acetate buffer solution. At pH 2.94 a nearly symmetric cyclic voltammetric wave due to an irreversible weak adsorption of CV on mercury was obtained at concentration of $0.53{\mu}mol\;dm ^{-3}$. Under these conditions, CV adsorbes in a monolayer. Upon increasing the concentration, the symmetry of the wave decreases; it can be attributed to a mixed diffusion adsorption process. The amount of the adsorbed catechol violet on the HMDE expressed as surface concentration as well as the surface areaf occupied by one molecule$(\sigma)$ were calculated. It was found that the values obtained for f and o utilizing cyclic voltammetric and chrono-coulometry are almost identical. A 1:1 and 1:2 Th (IV)-CV complexes are formed on addition of thorium (IV) to catechol violet. These complexes are adsorbed and reduced on the HMDE at more negative potentials than the peak potential of free CV, Using the square-wave (SW) technique, the adsorptive cathodic stripping voltammetry, ACSV, of these complexes was studied. It was found that the SW-ACSV of Th(IV)-CV can be applied to the determination of thorium at the nanomole level. Optimum conditions and the analytical method of determination were presented and discussed.

• Analytical Science and Technology
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• v.10 no.2
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• pp.114-118
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• 1997

A stripping voltammetric scheme for the determination of osmium, based on the adsorptive accumulation of osmium in the presence of hydroxylamine, was described. Cyclic voltammetry was used to characterize the redox and interfacial processes. Optimal experimental conditions were found to be a stirred 0.05M hydroxylamine hydrochloride solution(pH 1.8), accumulation at -0.65V for 60s, and a differential pulse mode with a scan rate of 10mV/s. The detection limit was $6.3{\times}10^{-8}M$(12ppb) with the optimal condition.

• Bulletin of the Korean Chemical Society
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• v.15 no.12
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• pp.1035-1037
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• 1994

An ultrasensitive and selective stripping voltammetric scheme for the determination of rhodium is described. By the use of combined accumulation and catalytic effects in formaldehyde-hydrochloric acid medium, substantial improvement in the limit of detection can be obtained. Optimal experimental conditions were found to be 0.42 M hydrochloric acid solution containing 0.008${\%}$ formaldehyde, an accumulation potential of -0.70 V (vs. Ag/AgCl) and an accumulation time of 20 s. The stripping mode was differential pulse voltammetry. In these conditions the limit of detection lies at 2 ${\times}$ l0$^{-12}$ M (0.21 ppt). The relative standard deviation at 5 ${\times}$ l0$^{-11}$ M was 4.9${\%}$ (n=5). There were no serious interferences from other platinum group metal ions being the tolerable amounts more than 500 times that of rhodium.

• Journal of the Korean Chemical Society
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• v.41 no.10
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• pp.557-560
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• 1997

• Bulletin of the Korean Chemical Society
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• v.25 no.8
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• pp.1125-1129
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• 2004

This work assesses the potential of natural Analcime Zeolite as an adsorbent for preconcentration of lead (II) traces. Lead is quantitatively retained on 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol by column method with Analcime in the pH range of 5-6.5 and 2 mL $min^{?1}$ flow rate. Lead was removed from the column with 10.0 mL of 4 M hydrochloric acid and was determined by anodic stripping differential pulse voltammetry. 0.5ppb detection limit was obtained and linear dynamic range was 3 to $1.2{\times}10^5$ ppb in final solution with correlation coefficient of 0.999 and relative standard deviation of ${\pm}$ 1.2% (for eight replicate determination of 2.5 ${\mu}g\;mL^{?1}$ of lead). Various parameters such as the effect of pH, flow rate, instrumental conditions and interferences of some ions on the determination of lead have been studied in detail for optimization of conditions. The method was successfully applied for determination of lead in various samples.

• 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.

• Analytical Science and Technology
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• v.10 no.3
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• pp.216-224
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• 1997

In the study of cyclic voltammogram of rubeanic acid, rubeanic acid has two reduction peaks; first peak is similar with that of $S^{2-}$ and thiourea, which is conceded to by HgS, second peak is very weak and unidentified. The study also describes the differential pulse cathodic stripping voltammetric method for the determination of rubeanic acid. The followings were optimal conditions of rubeanic acid for the study : 0.05M borate buffer solution(pH 10.0) ; an accumulation potential of -0.30V(vs. Ag/AgCl); accumulation time of 120sec. : scan rate of 10mV/sec. The detection limit of trace analysis shows $2.7{\times}10^{-8}M$ of rubeanic and at optimal conditions.

• YAKHAK HOEJI
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• v.27 no.1
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• pp.1-10
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• 1983

Voltammetric deposition and differential pulse anodic stripping (DPASV) of Ge(IV)at a gold electrode was investigated. Germanium (IV) exhibits two stripping peaks by DPASV in sodium borate solution, the first peak at about -1.1v. vs SCE and the second one, in the range of -0.6 to -0.2v. vs SCE. Factors affecting the sensitivity and precision included the nature of working electrode, supporting electrolytes, deposition potential, deposition time, pH, pulse height, voltage scan rate. The relative standard deviation of the measurements of the peak currents, for 100ng/ml Ge(IV), was less than ${\pm}3%$. The detection limit of Ge(IV) was 0.01ng/ml. Percent recovery in the extraction procedure of Ge(IV) from matrices by benzene in c-HCl, followed by back extraction with saturated borax solution, ranged from 96 to 104%.

• Food Engineering Progress
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• v.21 no.2
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• pp.180-186
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• 2017

Salt, as food, is the most essential element for human survival due to its significant physiological functions. Here, we report the simultaneous detection of Pb and Cd in sea salt by square wave anodic stripping voltammetry (SWASV). Stripping voltammetric measurements were conducted using a manufactured rotating disk electrode system (MRDES). The detection limit was $3.6{\pm}0.18{\mu}gL^{-1}$ for Pb and $3.9{\pm}0.37{\mu}gL^{-1}$ Cd in NaCl solution. When the pH increased from 5.5 to 8.5, the peak currents of Pb and Cd decreased. At a pH of 8.3, the ratio of the current drop compared with that at a pH of 5.5 was 0.6 for Pb and 0.73 for Cd. The concentrations corrected by the current drop are in agreement with the concentrations obtained with ICP (inductively coupled plasma). This system demonstrates the reliable detection of heavy metals in aqueous media and, at a high $Na^+$ concentration, the successful application for the determination of Pb and Cd in sea salts.