• Electrical & Electronic Materials
• /
• v.8 no.3
• /
• pp.254-260
• /
• 1995

A method is described for the design and fabrication of the sensor interface circuits on the Clark electrodes for the dissolved oxygen(DO). The discussion includes a method for the +5 V single-supply driving for the sensor circuits, which has low power comsumption for the front-end electronics. DO probe under test is composed of the Clark electrode with silver anode, gold cathode and the electrolyte of half saturated KCI solution and the FEP teflon memtrance for the oxygen penetration. Typical polarograms for the DO probes by using this sensor circuit reveals high accuracy over 99% of the I to V conversion. Partial pressure of oxygen obtained from the polarograms are well suited to the results calculated. It is expected that the proposed sensor circuits can be utilized into the customized IC for the battery-driven small-size DO meters.

• Journal of the Korean Chemical Society
• /
• v.14 no.2
• /
• pp.141-145
• /
• 1970

The reduction of Mo-thiocyanate (V) complex on dropping mercury electrode has been studied at ionic strength 0.6 with pH less than 2.3. D-C polarogram obtained from acidic solutions are reversible, diffusion controlled current. The electrode reaction of Mo-thiocyanate(V) may be represented as follows. $MoO(SCN)_3\;+\;2H^+\;+\;2e\;{\to}\;Mo(SCN)_2{^+}\;+\;H_2O\;+\;SCN^-$From this reaction, the half wave potential assumed to be $E_{1/2}\;=\;E_0'\;-\;0.059\;pH\;-\;0.03\;log{\;frac{[Mo(SCN)_2{^+}][SCN^-]}{[MoO(SCN)_3]}}$Considering the dissociation of this complex, however, it was estimated that the electrode reaction may be written by. $MoO^{+3}\;+\;3SCN^-\;+\;2H^+\;+\;2e\;{\to}\;Mo(SCN)_2{^+}\;+\;SCN^-\;+\;H_2O$.

• Journal of Environmental Science International
• /
• v.11 no.2
• /
• pp.131-137
• /
• 2002

The chemical behavior and properties on the redox state of environmental pollutant has been investigated by electrochemical methods. We carried out to measure the variations in the redox reaction of differential pulse polarogram and cyclic voltammogram. The results observed the influences on redox potential and current of various factors with temperature and pH. These were established factors as the effect of the redox reaction. It can be clearly recognized that the electrode reaction are from qusi-reversible to irreversible processes. Also, it was mixing with reaction current controlled. The bits-phenol A in the waste water was made to compound with cobalt ion and it take away from the separation into compound. The $Co(BPA)_2$ compound was not found to be dissociation in waste water. However, this compound is avery unstable(K=1.02) and for a while, it was to be a dissociation. Therefore, we believed that it was likely to a toxic substance.

• Journal of the Korean Chemical Society
• /
• v.5 no.1
• /
• pp.84-87
• /
• 1961

A polarographic method for rapid determination of Uranium in the presence of foreign ions was proposed. The method is based on the measurement of polarogram in the sulfuric acid as supporting electrolyte. In this medium Uranyl ions give well defined reduction waves, and half-wave potentials are -0.19V vs. S.C.E. as first wave, and uncertain volt. vs. S.C.E. as second wave in $2.4 N-H_2SO_4.$ The first wave has a linear relationship between the concentration of Uranyl ion and wave height. The author also studied a method for rapid determination of Uranium in Korean monazite sand without eliminating the foreign ions. The Korean monazite sands were analyzed by this method and satisfactory result were obtained.

• Journal of the Korean Chemical Society
• /
• v.19 no.6
• /
• pp.428-433
• /
• 1975

500 ml of a sample water was extracted with 10 ml of 0.01 % dithizone-$CHCl_3$three times. When $CHCl_3$ layer was back extracted with 10 ml of 0.1 N HCl containing mercuric ion, the free metal ions come into aqueous layer. The aqueous layer was added with 2 ml of 2 N KCl and was washed with 10 ㎖ of $CHCl_3$two times in order to remove the trace dithizone, and then was recorded square wave polarogram. The concentration of copper, lead and cadmium can be determined up to 3 ppb and that of zinc up to 14 ppb with an error of 10 %.

• Journal of the Korean Chemical Society
• /
• v.37 no.8
• /
• pp.730-734
• /
• 1993

The electrochemical reduction behavior or Biliverdin (BV) in N,N-dimethylformamide solvent was studied by DC polarography, cyclic voltammetry and the controlled potential coulometry. The reduced product was indentified by UV-Vis spectroscopy. In DC polarogram, two reduction waves of BV were founded. The half wave potentials of two reduction waves were -0.71 and -0.91 V vs. Ag/Ag$^+$ respectively. The current type of the 1st reduction wave was diffusion-controlled and the 2nd was diffusion current containing a little kinetic current. The 1st electrochemical reduction process was irreversible and BV reduced to Bilirubin.

• Journal of the Korean Chemical Society
• /
• v.35 no.6
• /
• pp.673-679
• /
• 1991

The electrochemical reduction of N-tert-butylbenzothiazole-2-sulfenamide (TBBS; vulcanization accelerator) was investigated by direct current, differential pulse polarography, cyclic voltammetry and controlled potential coulometry. The electrode reduction of TBBS proceeded E-C-E-C reaction mechanism by four electrons transfer at irreversible one wave (-2.31 volts vs. Ag/0.1M AgN$O_3$ in AN). As the results of controlled potential electrolysis, mercaptobenzothiazole (MBT), benzothiazole disulfide (MBT dimer) and extricated sulfur were products which followed by cleavage of the sulfenamide (-S-N=) bond. Upon the basis of products analysis and polarogram interpretation with pH variable, electrochemical reaction mechanism was suggested.

• Journal of the Korean Chemical Society
• /
• v.35 no.6
• /
• pp.680-688
• /
• 1991

The electrochemical reduction of N-oxyldiethylenebenzothiazole-2-sulfenamide (ODBS; vulcanization accelerator) was investigated by direct current polarography, differential pulse polarography, cyclic voltammetry and controlled potential coulometry. The irreversible electrode reduction of ODBS proceeded E-C-E-C reaction mechanism by three electrons transfer with irreversible one wave (-1.86 volts vs. Ag/0.1 M AgN$O_3$ in AN). As the results of controlled potential electrolysis, mercaptobenzothiazole (MBT), benzothiazole disulfide (MBT dimer) and extricated sulfur were products which followed by cleavage of the sulfenamide (-S-N=) bond. Upo the basis of products analysis and polarogram interpretation witli pH variable, electrochemical reaction mechanism was suggested.

• Journal of the Korean Chemical Society
• /
• v.33 no.6
• /
• pp.614-622
• /
• 1989

The electrochemical reduction of ${\alpha},{\beta}$-dibenzyl N-benzylidene L-aspartate in 0.1M LiCl ethanol solution was investigated by direct current (DC), differential pulse (DP) polarography, cyclic voltammetry and controlled potential coulometry(CPC). The irreversible reductive amination of imino group proceeded to form ${\alpha},{\beta}$-dibenyl N-benzyl L-aspartate by CEC or CE electrochemical reaction mechanism at the first reduction step (-0.92 volts vs. Ag-AgCl). The polarographic reduction wave was slightly suppressed due to inhibitory effect of micelle, while the irreversibility was increased according to the increase of Triton X-100 concentration. Upon the basis of product analysis and polarogram interpretation with pH change, possible CE electrode reaction mechanism was suggested.

• Journal of the Korean Chemical Society
• /
• v.20 no.6
• /
• pp.494-499
• /
• 1976

The extraction-polarographic method applied to the determination of micro amount of chromium (Ⅵ). Chromium(Ⅵ) was extracted into methylisobuthylketone(MIBK) layer containing diethyldithiocarbamate(DDTC) as Cr(Ⅲ)-DDTC complex from acetate buffered aqueous, solution of pH 5.4 and the direct current polarogram for the extract was recorded after addition of sodium perchlorate as supporting electrolyte. The reduction current was diffusion controlled. And the half wave potential of this reduction wave was -0.81 volt vs. SCE. The diffusion current was proportional to the chromium concentraticn in aqueous solution in the range of 8∼160 ppm. And the chromium(Ⅵ) could be selectively determined in the presence of chromium(Ⅲ), since the chromium(Ⅲ) did not interfere up to twice the amount of chromium(Ⅵ). Many of other metals such as Mn(Ⅱ), Cu(Ⅲ), Zn(Ⅱ), Mg(Ⅱ), Ni(Ⅱ) and Ag(Ⅰ) were found to have no effect even when present in 1000 times the amount of chromium (Ⅵ).