In Japan salt-making factories produce salt from the brine obtained by concentrating sea water through an ion-exchange membrane electrodialyzer. Determining the composition of the brine plays an important role in the operation of the electrodialyzer. I tried to use ion-exchange electrodes for determining the brine composition. However, it was impossible to do this directly without such a means as the addition of ionic-strength adjustors, because the electrode potential was affected by the

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... strength of the brine. On the basis of these experimental results, I developed a method for determining the brine composition without diluting the brine and adding ionic strength adjustors. This new method corrects measurements of the target ion electrode potential by using the chloride electrode potential, which has a linear relationship to the ionic strength of the brine, thus making it possible to determine the brine composition by using calcium, potassium, divalent-cation and chloride electrodes.