Accuracy of Potentiometric Methods for Measuring Ion Activity in Solutions

What is it about?

Structural realizations of the digital ion selective transducers, constructed on different rutotom principles are proposed: ADC of the successive approximation, time-pulse conversion and voltage to frequency conversion. Corresponding conversion equations are obtained, their static characteristics are constructed, measurements errors, emerging as a result of using one or another construction principles are investigated. As a result of the research, it was found that in order to improve the measurement accuracy, it is advisable to introduce an additional measuring temperature channel. To ensure high accuracy of ion activity measurement in the lower measurement range of 0.3 pX and to take into account the temperature deviation by 1 degree Celsius, it is necessary to construct a temperature measuring channel with a relative error of 0.05%.

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Why is it important?

Three principles for implementing measuring channels for measuring ion concentrations are considered. The methodological components of the error that arise due to the principle of implementing the measurement conversion of the input quantity into a digital code have been modeled, calculated and compared.