Methods for Constructing High-precision Potentiometric Measuring Instruments of Ion Activity

Corresponding con-version equations are obtained, their static characteristics are constructed, measurements errors, emerging as a result of using one or another construction princi-ples are investigated. As a result of the research, it was found that in order to im-prove the measurement accuracy, it is advisable to introduce an additional measuring temperature channel. Of the proposed three methods for measuring the activity of ions, the third option with a relative error of
$6.5^{\star}10^{-7}\%$
in the measurement range from 0.3 to 7 pX, which is based on the principle of converting voltage into frequency, has the highest measurement accuracy.