• Journal of the Korean Chemical Society
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• v.48 no.2
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• pp.137-143
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• 2004

The determination of 2-mercapto-1-methyl-imidazole (MMI) in 5.0${\times}10^{-2}$ M lithium perchlorate suporting electrolyte has been investigated by the differential pulse polarography. The optimum condition of MMI analysis was as follows; -0.9 volts initial potential, 0.08 mV pulse height, 2 mV/sec scan rate, and medium mercury drop size. Standard calibration curve showed a good linearlity in the range of 1.0${\times}10^{-7}M\;to\;8.0{\times}10^{-5}$ M and the detection limit has been (2.2${\pm}0.1){\times}0.1^{-9}$ M. This method was applicated for the determination of MMI in antithyroid drug without interference of additives.

• The Journal of Natural Sciences
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• v.7
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• pp.37-46
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• 1995

Electrochemical behavior of $Ln^{3+},$-ALC complexes($Gd^{3+},$ $Tb^{3+},$ $Dy^{3+},$ $Ho^{3+},$ $Er^{3+},$ $Yb^{3+}$ and $Lu^{3+}$-alizarin complex-one) has been investgated by d.c polarography, differential pulse polarography and cyclic voltammetry. The reduction mechanism of ALC comes to the conclusion that the two electron make one step of reversible processes, and that there is few adsorption in the electrode reaction. The new complex is made from one lanthanide ion and one ALC. This complex is proven to make an adsorptive complex wave, by the experiments of differential pulse polarography and cyclic voltammetry. The reduction potential of complex wave($P_2$)turns up more negatively than ligand wave($P_1$) does. Linear calibration curves of the decreasing P1 and increasing $P_2$ is obtained when the lanthanide concentration varys from $2.5X10^5$M to $1X10^4M$.

• Analytical Science and Technology
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• v.13 no.1
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• pp.1-4
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• 2000

Determination of trace rhodium, based on catalytic reduction of protons by the adsorbed Rhformaldehyde complexes formed in formaldehyde-hydrochloric acid medium, was demonstrated. The condition for the measurements of Rh at trace levels was 0.004%(w/v) formaldehyde-0.75M hydrochloric acid. In this medium detection limit was $7.0{\times}10^{-12}M$ and the linear dynamic range was $1.0{\times}10^{-11}{\sim}1.0{\times}10^{-8}M$ Rh. There were no interferences from other platinum group metal ions even in the presence of a 500-fold excess.

• The Journal of Natural Sciences
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• v.11 no.1
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• pp.33-39
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• 1999

Electrochemical behaviors of $Sm^3+$-ARS complexes has been investigated by d.c.polarography, differential pulse polarography and cyclic voltammetry. $Sm^3+$forms 1 : 3 adsorptive complexes with ARS.The reduction potential of complex wave $(P_2)$ shifted more negatively than the ligand wave $(P_1)$. The linear calibration curves of decreasing $P_1$ and increasing $P_2$ is obtained when $Sm^3+$ concentration varies from TEX>$2{\times}10^{-6}$ M to $3.2{\times}10^{-5}$ M.

• Journal of the Korean Chemical Society
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• v.37 no.12
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• pp.1053-1059
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• 1993

The determination of iron(Ⅱ), iron(Ⅲ) and total iron was studied by differential-pulse and Tast polarography in 0.1 M acetate buffer solution at pH 4.60, Half wave potentials of iron(Ⅱ)-DTPA and iron(Ⅲ)-DTPA complexes were -0.150V vs. SCE reference electrode. In the presence of DTPA the redox process of iron(Ⅱ) and iron(Ⅲ) was reversible. Linear calibration plots were obtained for iron(Ⅱ) and iron(Ⅲ) concentration of 0.2∼1.0 mM. The detection limits of iron(Ⅱ) and iron(Ⅲ)by Tast polarographic method were 0.05 mM and 0.07 mM, respectively.

• Journal of the Korean Chemical Society
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• v.39 no.1
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• pp.35-39
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• 1995

Simultaneous measurements of trace platinum and rhodium, based on catalytic reduction of protons by the adsorbed Pt-formazone and Rh-formaldehyde complexes formed in formaldehyde-hydrazine-sulfuric acid medium, were demonstrated. The conditions for the measurements of Pt and Rh both present at trace levels (>10-10 M) were 0.004% (w/v) formaldehyde-0.0012% (w/v) hydrazine-0.75 M sulfuric acid. In this medium method detection limits are 7.3${\times}$10-11 M Pt and 3.2${\times}$10-11 M Rh. And dynamic ranges are 5${\times}$10-10~6${\times}$10-8 M and 1${\times}$10-10∼2${\times}$10-8 M for platinum and rhodium respectively. In the linear dynamic ranges, Rh and Ir interfere platinum in the presence of only 10 and 100 times that of Pt respectively. There are no interferences from other platinum group metal ions for rhodium even in the presence of a 500-fold excess of Ir(IV), a hundredfold excess of platinum.

• Analytical Science and Technology
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• v.5 no.3
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• pp.249-261
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• 1992

Electrochemical behavior of the heavy lanthanide complexes of alizarin red S(ARS) has been investigated by d. c. polarography, differential pulse polarography and cyclic voltammetry. The reduction mechanism at a mercury electrode of alizarin red S as a complexing ligand showed a one step of two-electron transfer and the electron process is found to be reversible. Alizarin red S forms a 3:1 adsorptive complexes with lanthanides and the complexes are reduced via one step of two-elctron. The reduction potential of complex wave($P_2$) shifted more negatively than the ligand wave($P_1$). The linear calibration curves of the decreacing $P_1$ and increasing $P_2$ is obtained when the lanthanide concentration varies from $2.0{\times}10^{-6}M$ to $6.4{\times}10^{-5}M$ under the condition of pH 9.5, 0.1M LiCl and $1{\times}10^{-3}M$ ARS.

• Journal of the Korean Chemical Society
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• v.34 no.6
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• pp.561-568
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• 1990

Voltammetric behavior of some light lanthanide ions (La$^{3+}$, Pr$^{3+}$, Nd$^{3+}$, Sm$^{3+}$, and Eu$^{3+}$) in various supporting electrolytes has been investigated by several electrochemical techniques. The peak potentials and the peak currents, their dependency on the concentration, temperature and pH effects, the reversibility of the electrode reactions are described. The reduction of La$^{3+}$, Pr$^{3+}$ and Nd$^{3+}$ in 0.1 M lithium chloride proceeds by a three-electron change directly to the metallic state (Ln$^{3+}$ ＋ 3e- → Ln$^0$) and charge transfer is totally irreversible. However, the reduction of Sm$^{3+}$ in 0.1 M tetramethylammonium iodide and Eu$^{3+}$ in 0.1 M lithium chloride proceeds in two stages (Ln$^{3+}$ ＋ e- → Ln$^{2+}$ and Ln$^{2+}$ ＋ 2e- → Ln$^0$). At pH values lower than ca.4 the hydrated lanthanide species (Ln(OH)$^{2+}$) reduced before the lanthanide ions (Ln$^{3+}$) due to the catalytic effect of hydrogen ions, and peak current increase with in the order Eu$^{3+}$ < Sm$^{3+}$ < Nd$^{3+}$ < Pr$^{3+}$ < La$^{3+}$ in differential pulse polarography. Some representative plots of $i_{pc}V^{-1/2} (proportional to current function) vs. V show considerable influence of hydrogen ion/lanthanide ion concentration in cyclic voltammetry. It is shown that a reaction of lanthanide ions with proton and/or water and catalytic reaction is enhanced at lower pH and at decreased lanthanide ion concentration.

• Analytical Science and Technology
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• v.8 no.1
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• pp.17-23
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• 1995

The determination method of 2-mercapto-1-methyl-imidazole(MMI) in $5.0{\times}10^{-2}M$ lithium perchlorate solution has been investigated by the differential pulse polarography. The optimum conditions for the determination of MMI were as fellows; -0.9 volt(vs. Ag/AgCl) initial potential, 80mV pulse height, 2mV/sec scan rate, and medium mercury drop size. The calibration curve showed a good linearlity in the range of $1.0{\times}10^{-7}M$ to $8.0{\times}10^{-5}M$ and the detection limit was $2.2{\times}10^{-9}M$. This method was applicable to the determination of MMI in thyroid drugs without interference from the additives.

• Analytical Science and Technology
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• v.7 no.3
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• pp.361-369
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• 1994

Voltammetric behavior of some light lanthanide ions($La^{3+}$, $Pr^{3+}$, $Nd^{3+}$, $Sm^{3+}$ and $Eu^{3+}$) in acetonitrile(AN) and dimethylformamide(DMF) has been investigated by direct current, differential pulse polarography and cyclic voltammetry. The reduction of $La^{3+}$, $Pr^{3+}$ and $Nd^{3+}$ in 0.1M TEAP proceeded directly to the metallic state through three-electron charge transfer of irreversible process where as $Sm^{3+}$ and $Eu^{3+}$ proceeded by charge transfer of two steps. As the results of the cyclic voltammetric investigation, the first step reduction of $Sm^{3+}$ and $Eu^{3+}$ were a quasireversible reaction, the second step reductions were an irreversible reaction. The cathodic peak currents of the differential pulse polarogram showed adsorptive properties at lower sweep rates and high concentrations of these metal ions. The peak potenital was shifted to a negative petential and the peak current decreased with the increase of percentage of water in AN. On the other hand, the peak potential was shifted to a positive potential and the peak current decreased with an increased percentage of water in DMF.