@article{oai:barrel.repo.nii.ac.jp:00004198, author = {片岡, 正光 and 神原, 冨民}, issue = {10}, journal = {分析化学}, month = {}, note = {バナジウム(IV)は,塩素酸イオンによるヨウ化物イオンのヨウ素への,酸性溶液中での酸化反応を触媒する.その反応速度式を積分すると,log[I^-]は時間tとともに直線的に変化するので,電位変化速度を知ることにより,触媒バナジウム(IV)の定量が可能である.検量線を作成するにあたって,ヨウ化カリウム,硫酸および塩素酸カリウムの最適濃度の決定には, 実験計画法を適用した.本法によれば,0.55〜2.8μM のバナジウム(IV)の定量が可能であり,比色法とほぼ同じ感度を示した.また,妨害イオンについても検討を行なった. The oxidation of iodide ion to iodine by chlorate ion takes place in an acidic environment according to
ClO₃^-+6I^-+6H⁺=Cl^-+3I₂+3H₂O
and is catalysed by V(IV). The reaction rate is determined by measuring the iodide ion concentration, which can easily be determined by the potential of iodide-selective electrode. Integration of the kinetic eqn. yields log[I^-]=-K·C_k[ClO₃^-][H⁺]2t+log[I^-]
where K is the rate constant, C_k the concentration of V(IV), t time, and [I^-] the initial concentration. The potential change of the iodide-selective electrode is recorded, from which the time required for the potential change of 40 mV is estimated at the linear part of potential-time curve. The rate is proportional to the concentration of catalyst and so it is possible to determine a small amount of V(IV).
The most suitable concentrations of KI, H₂SO₄ and KClO₃ were decided by the method of experimental design of three-sided classification. The variance ratio concerning the concentration of KI, as well as KClO₃, is very high, i.e. the rate of reaction depends significantly on these concentrations. It is not found, however, that there is a strong interaction between the KI, the H₂SO₄ and the KClO₃ concentration. The most suitable concentrations of KI, H₂SO₄ and KClO₃ are 2 μM, 1 mM and 0.3 M, respectively. A calibration curve with a good linearity was obtained and by this method it is possible to determine V(IV) in the concentration range from 0.55 to 2.8 μ mol dm^-3 in the reaction solution. This sensitivity is almost the same as that of spectrophotometric method developed by Yatsimirskii. Fe(III) shows a strong interference.}, pages = {1157--1160}, title = {ヨウ化物イオン電極によるバナジウム(IV)の接触分析}, volume = {23}, year = {1974} }