Derivative time-root potentiometry with an analog device and a microcomputer.

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  • NAKANO Kunio
    Department of Chemistry, College of Science, Rikkyo University
  • KATO Nakahide
    Department of Chemistry, College of Science, Rikkyo University
  • NISHIDA Makoto
    Department of Chemistry, College of Science, Rikkyo University
  • TANAKA Yayoi
    Department of Chemistry, College of Science, Rikkyo University
  • NAKANISHI Masaki
    Department of Chemistry, Faculty of Science, Ochanomizu University
  • FUJIEDA Shuko
    Department of Chemistry, Faculty of Science, Ochanomizu University

Bibliographic Information

Other Title
  • アナログ回路及びマイクロコンピュータによる時間平方根微分ポテンショメトリーの検討
  • アナログ カイロ オヨビ マイクロコンピューター ニ ヨル ジカン ヘイホウコ

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Abstract

Derivative time-root potentiometry can eliminate the disadvantage of conventional chronopotentiometry and a derivative time-root potentiogram can be treated as an ac polarogram. And this method requires shorter time for the measurements than polarography and the half-wave potential can be easily obtained from the peak potential. A derivative time-root potentiograph of analog device was constructed. However, its characteristics depended strongly on the time constant of the differential circuit, that is, to increase the time constant resulted in to suppress the peak height of the signal in the earlier stage, and when the time constant was small, the later signal was buried in the noise. Consequently, the determination was limited only in a narrow concentration range. For example, Ti(IV), Cd(II) and Pb(II) could be determined between the range from about 0.1 to 0.4 mM. Therefore, the derivative time-root potentiograph with a microcomputer was assembled and a computational method was employed for the differential operation instead of the analog circuit. The treatment of data was as follows: An original chronopotentiogram was smoothed by 5 points moving average and then it was converted into a time-root potentiogram. The potentiogram was again converted into a curve of uniform interval voltage (1 mV) and then it was differentiated. This operation resulted a reproducible peak potential and peak height, which was proportional to the sample concentration. Pb(II) can be determined between the range from 0.16 to 2.2 mM by means of this method. This suggests that read-out method as a derivative time-root potentiogram with a microcomputer will be useful way of determination.

Journal

  • BUNSEKI KAGAKU

    BUNSEKI KAGAKU 34 (11), 686-691, 1985

    The Japan Society for Analytical Chemistry

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