対流電極を用いる電流滴定-2-

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Amperometric titrations of Cd(II) and Pb(II) in 0.1M KNO3 containing 0.2M ascorbic acid with EDTA are investigated using the DME and the pushed-out mercury drop convection electrode (PMDCE), previously reported by the authors {J. Suzuki, T. Ozaki : Bull. Chem. Soc. Japan, 37, 230 (1964)}. The best conditions for the reduction of dissolved oxygen by ascorbic acid are found to be in the pH range of 6 to 7, and the addition of small amounts of cupric copper (8 × 10-8M) increases the reducing velocity remarkably with no effects upon the results. It is unnecessary to remove the dissolved oxygen by passing N2 or H2 gas through the sample solution, therefore the time required for the analytical procedure can be shortened considerably. Current-potential curves of Pb(II), Cd(II) and Tl(I) in 0.1M KNO3 containing 0.2M ascorbic acid are investigated with the PMDCE and fairly reproducible waves are obtained. Pb(II) and Cd(II) (both 10-5M) can be determined by the amperometric titration with EDTA within the error of about 0.5% in both cases. Simultaneous determinations of Pb(II) and Tl(I) are also carried out with the error about 1.5% or below.
社団法人日本分析化学会の論文