高周波を用いる容量分析法の硏究(第1報)

Abstract

The electrometric titrations using high frequency oscillator have recently been reported-the method being based on the sudden change of the electric characteristics of the solution at the equivalent point. When the beaker containing the sample solution is inserted as an element of the oscillating circuit and titration is carried out with standard solution, the electric characteristics of the solution change discontinuously at the end point and so the oscillating frequency f, plate current Ip of the oscillator bulb, or the grid current Ig will change. Plotting the change of f, Ip or Ig against the added volume of the reagent, the end point is decided graphically. The author made the researches of this titration by measuring the grid current and the satisfactory result was obtained. In this paper, the circuit and the result obtained are reported. The circuit is analogous to that of Anderson et al., but is modified as follows. Anderson et al. used the oscillator tube UN 955, but the change in the grid current by the titration is so small that they measured it by mirror galvanometer and it is not so good for the practical work. We modified the circuit by the use of the bulb 6YL3 and the change of the grid current can be measured by microammeter of 50 μA full scale and the special device was made for the condensor which envelopes the titration vessel. The AC source for this apparatus is stabillized using constant voltage transformer and the argon bulb VR 105/30 is used for stabilizing the plate voltage. Acidimetric titrations, argentometric titrations were examined and applied to the determination of the chloride ion in drink water. These results obtained by this method were discussed.