A device for measuring ionic activity is composed of:
a block of insulating material having a hollow space therein, a
solution-receiving surface area in which a pair of openings for receiving
a sample solution and a reference solution separately are provided, a
plurality of solution-supplying surface areas in each of which a pair of
openings for supplying outside the sample solution and the reference
solution separately are provided;
a bridge member fixed on the solution-receiving surface area;
a guide member placed in the hollow space which assists to transmit
separately the sample solution and the reference member in the hollow
space; and
two or more ion selective electrodes each of which is placed on each
solution-supplying surface area.
