• Analytical Science and Technology
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• v.8 no.3
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• pp.285-292
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• 1995

Uranium has variable oxidation states(${UO_2}^{+2}$, $UO^{+2}$, $U^{+4}$, $U^{+3}$) and 1-(2-Pyridylazo)-2-naphthol forms a very stable chelate with Uranium(${UO_2}^{+2}$). The determination method of Uranium(${UO_2}^{+2}$) in 0.1M Borate buffer(pH 7.10) has been investigated by adsorptive stripping voltammetry. The optimum conditions were PAN concentration of $5{\times}10^{-7}M$, accumulation potential of 0.00V(vs. Ag/AgCl) and accumulation time of 120sec. The calibration curve was linear over the range of $5{\sim}60{\mu}g/L$ and the various metal ions did not interfere with the determination Uranium(${UO_2}^{+2}$) except Cu(II) and Co(II).

• Journal of the Korean Chemical Society
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• v.43 no.1
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• pp.36-41
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• 1999

The adsorptive stripping voltammetric determination method of trace germanium (IV) using mercaptoacetic acid as a ligand was studied. Optimal conditions were found to be 0.25 M NaCl solution (pH 6.0) containing mercaptoacetic acid concentration of $5.0{\times}10^{-6}M$. The peak potential appeared at - 1.402 V vs. Ag/AgCl. Effects of sodium chloride concentration, mercaptoacetic acid concentration, and accumulation time for the complex of Ge(IV)-Mercaptoacetic acid on the peak current were studied. Amberlite IRC-718 chelating resin was applied to the separation of Ge(IV) from other metal ions.

• Analytical Science and Technology
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• v.6 no.3
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• pp.247-254
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• 1993

Strontium can not be determined by conventional dc polarography method since it is very difficult to be reduced at the drop mercury electrode(DME) in aqueous solution. However the analytical sensitivity was improved by adsorptive stripping voltammetry in which electro-reduction of ligand in a complex formed between strontium and o-cresolphthaleoxone was performed. Strontium could be determined in range of $5{\sim}30{\mu}g/L$ concentration. This method was affected by coexistent alkali earth metal ions. Consequently ion exchange separation is recommended to analyze strontium in samples.

• Journal of the Korean Chemical Society
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• v.35 no.5
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• pp.506-511
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• 1991

A sensitive adsorptive stripping voltammetric study was investigated on the complex of indium with morin at a hanging mercury drop electrode in 0.1 M acetate buffer (pH 3.20) solution. The adsorption phenomena were observed by differential-pulse voltammetry. The effects of various analytical conditions were discussed on the reduction peak current of the adsorbed complex on the surface of HMDE. Interferences by other trace metals and surfactant were also discussed. Detection limit was 2.6 nM of indium after 90 second deposition time, and the relative standard deviation (n = 7) at 4TEX>${\mu}g$/l indium was 2.0%.

• 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.

• 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.

• Analytical Science and Technology
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• v.12 no.1
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• pp.34-39
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• 1999

Estrone such as estriol and estradiol can not be determined by votammetric methods, because these are electrochemically inactive in the potential windows for mercury drop electrode. Nitro-derivatives of estrone are electro active and nitration of estrone is accomplished by heating the solution involving estrone and sodium nitrite in a water-bath at $100^{\circ}C$ for 30 min. Such nitro-derivatives are determined directly by voltammetry. The electrochemical behavior for nitrated estrone was investigated by cyclic voltammetry. The trace estrone was determinated by differential pulse adsorptive cathodic stripping voltammetry. Nitrated estrone gives a well defined voltammetric wave at ca. - 0.61 V (vs. Ag/AgCl electrode). The electrochemical reaction was irreversible process in sodium borate buffer at pH 11 and nitrated estrone was strongly adsorbed on the surface of mercury electrode. The optimal experimental conditions for the determination of nitrated esterone were found to be 0.05 M sodium nitrate, 0.01 M sodium borate, pH 11.0, and an accumlation potential of 0.10 V (vs. Ag/AgCl). The detection limit was as low as $1{\times}10^{-9}M$ for estrone with 2 min accumulation time.

• 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.41 no.5
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• pp.246-250
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• 1997

In the presence of optimum amounts of hydroxylamine, trace ruthenium(III) can be conveniently determined in acidic (boric) media by coupling catalytic hydrogen processes with adsorptive accumulation of the catalyst, using differential pulse voltammetry. Cyclic voltammetry was used to characterize the redox and interfacial processes. Optimal experimental conditions were found to be a stirred borate (0.015 M, pH 2.5) solution containing 0.55 M hydroxylamine, a preconcentration potential of - 0.70 V, and a scan rate of 5 mV/s. With a 7 min accumulation period the detection limit was 3${\times}$10-10 M. The possible interferences by other platinum group metals are investigated.

• Journal of the Korean Chemical Society
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• v.39 no.1
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• pp.23-28
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• 1995

Differential-pulse cathodic stripping voltammetry was applied to the Sn(II)-cupferron complex in 0.1 M acetate buffer solution (pH 4.20). Effects of solution pH, ligand concentration, accumulation potential, and accumulation time on the reduction peak current for the adsorptive complex of Sn(II)-cupferron were investigated. Interferences by other metal cations that affected on reduction peak current were also discussed. The detection limit was 3.1${\times}$10-9 M (0.37 ppb) of Sn(II) with 60 seconds accumulation time. The relative standard deviation (n=8) for 5${\times}$10-8 M Sn(II) was 3.0%.