Culomtery is based on the exact analytical chemical reaction and recently developed techniques, but not so refered to a simple measurement of physical quantities as other instrumental analytical methods. Recently the controlled potential coulometry developed to be applied to analytical method for determination of actinide elements (U, Pu, etc.) and rare elements (Np, Ir, Ru, In, Tl, Tc, etc.) mostly in buffered tripolyphosphate medium, while the organic substances (olefin, carboxlic acids, aromatic amines, phenols, etc.) were successively determined by electrogenerated bromine according to coulometric titration method. Especially, the unstable reagents such as Cr(II) or Mn(III) are capable of being electrogenerated from Cr(III) by reduction or from Mn(II) by oxydation and are respectively employed in coulometric reduction or oxydation. I-Q (current-coulomb) recording coulometer is very available in all the coulometric methods, because the coulomb can be easily calculated by the intersection of extrapolated I-Q line to the electrolysis current axis. Another new technique in the coulometry is a coulogram method which uses a scanning coulometer and records a coulomb-potential curve of a reversible process under nearly equilibrium conditions. The circuit is shown in Fig. 1 and features a novel system for producing a scan rate that is an inverse function of electrolysis current. Application of the method was given to direct determination of Pu in irradiated nuclear fuel. Constant current potential limit coulometry (C.C.P.L.) has the simplicity of constant current method as well as the versatility of controlled potential method. In this methed the potential approaches to preset potential during the constant current electrolysis and then the electrolysis current is set forward low constant current. The block diagram is shown in Fig. 2. Operational amplifier was recently used in coulometer and potentiostat of coulometric apparatus, resulting the coulometry to develope as an exact and reliable method of analysis. The example is given in Fig. 3. For the purpose of increasing the sensitivity and precision, differential coulometric titration method is considered to be a versatile method of analysis. Moreover, high speed controlled potential coulometry which uses a large electrode area against solution volume and the stirring by ultrasonic device or nitrogen gas bubble is one of an interesting method for practical analysis. The trend of coulometer for coulometry is to use the integrating motor for measurement of coulomb. The coulometer using relaxation oscillator has not yet proved to show a linear relationship between electrolysis current and revoluton of the motor. Recently, voltage-to-frequency convertor type coulometer is available for rapid constant potential coulometry. The pulse which is proportional to the electrolysis current is read by electron counter. Pulse coulometry uses the constant pulse for electrolysis current and the coulomb cousumed for the electrolysis can be read by means of electron counter. The pulse generating circuit is shown in Fig. 4. The coulometric titration can be carried out in non-aqueous solution such as isopropanol. Recently, a coulometric acidimetry was proposed for determination of organic weak acids. The coulometric titration was also tried in fused medium of LiCl-RCl mixed salts. This coulometry has advantage in high sensitivity over polarography or chrono-potentiometry in fused salts medium. The constant potential coulometry with anodic stripping method to be available for determination of Zn Cd, or Ni fused salts bath. Stripping coulometry was applied to determination of organic compounds by means of using an acetyleneblack electrode which adsorbs or contains the organic compounds inn the apparatus shown in Fig.5 and strips coulometrically. Generally, the radical titration can not be available by conventional titration technique, but available by coulometric technique. Biphenyl in

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In 1958, D.L. Love reported the “New techique in radiochemical determinations using polarographic method”, in which he used a polarographic cell shown in Fig. 1. Mercury is placed in the side arm containing the platinum electrode and the cell with the stopcock closed is filled with carbon tetrachloride to just below the mercury pool electrode. The active solution is placed above the carbon tetrachloride and in contact with the electrode. The D.M.E. is placed in the solution. The purpose of the large volume of carbon tetrachloride in the other compartment is to keep the solution-carbon tetrachlo-ride interface at a constant height when the drops fall through the solution and are removed by turning the stopcock. The radiometric polarography thus introduced was improved and developed by Love-Greendale, the authors, Chmelar et al., and several other investigators. The design of the electrolytic cell depends on the nature of solvent in which mercury drops are collected. Several kinds of cells are shown in Fig. 1, 4, 5, and 6. The methods of cleaning the mercury collected, the minimum concentrations of several nuclides and the precision of the radiometric polarography are discussed. The derivation of the equation of radioactivity-potential curve is carried out and the method of calibration is stated. Five examples reported by Love and Love-Greendale are abstracted; 1. ⁶⁰Co, 2. ⁹⁵Zr-⁹⁵Nb, 3. ¹⁰⁶Ru-¹⁰⁶Rh, 4. ^99mTc, 5. ¹¹³Sn-^113mIn. Experiments on ⁶⁵Zn and ¹⁹⁸Tl reported by the authors are introduced. It is pos-sible to take quantitative radiometric polarogram on 2.4×10^-11M-¹⁹⁸Tl. Schaap Wild-man worked on 10^-16M-²⁰⁴ Tl. Coulometry has intimate connection with the radiometric polarography. Two examples, i.e. on ⁶⁰Co and radioactive silver are abstracted. On two systems of polarographic wave of catalytic nature, i.e. Th⁴⁺-NO₃ and ZrO⁺⁺-BrO₃⁺ systems, had been investigated by the authors. In both cases no catalyser metal does not deposit on mercury electrode at the potentials at which the catalytic waves appear. Radiometric polarography on ⁶⁰Co concerning the Brdicka catalytic wave of hydrogen is reviewed. The authors recognized an analogous formed cpm/t-E pattern of histidine to the ordinary polarogram, but both of the grams disappear on adding gelatin. Catalytic waves due to serum, cystine with gelatin or mecthylcellulose have cpm/t-E patterns which shows single wave of cobalt only and no catalytic peak form. Chmelar, Bfezina and Kalous29 worked out on the “radiopolarography” on ⁶⁰Co concerning the Brdicka reaction, and recognized the cpm - E patterns on cobalt wave and catalytic hydrogen peak form wave. On addition of sufficient gelatin, the cpm/t-E pattern is reduced to the same pattern as wave of cobalt, though there is no effect on the ordinary polarogram. The authors seem that the reason of cpm/t-E pattern corresponding catalytic wave of hydrogen is reduced to the induced reduction of ⁶⁰Co as can be seen at the potential of reduction of supporting electrolyte in many examples and as ⁹⁵Zn deposition at cadmium and cobalt waves. Colléns technique of isotope separation of ⁶Li and ⁷Li is introduced. The method, like Love's radiometric polarography, makes use of carbon tetrachloride to cathodic mercury, which is streaming through the electrolytic solution of lithium chloride.

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The correlation between the polarographic behavior of depolarizing substances and their chemical structure has been worked out from two points of view, one being expressed in terms of the half-wave potential, and the other in terms of their kinetic data of the electrode reaction.
In a reversible electrode process the half-wave potential relates to the approximate value of the standard redox potential. A more detailed investigation in this respect is the relevancy of the half-wave potential to the lowest unoccupied π orbital. On the other hand, the treatment of the kinetic parameters with respect to the chemical structure mostly remained only with a simple expression of the reversibility or of the irreversibility.
The present authors measured the more detailed kinetic parameters of the electrode reaction of cobalt (III) complexes of the [Co(NO₂)n(NH₃)m]^(3-n)+ type.

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[in Japanese]

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The system of Fe³⁺+ FMN in neutral oxalate medium was studied. It was found that two ferric ions combine with one FMN molecule, and that the system produces a kinetic current wave of Fe³⁺ liberated from Fe³⁺ - FMN complex.

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