ABSTRACT
Ion-selective electrodes comprise a class of primary elements used to obtain information related to the chemical composition of a process solution. Compared to other composition-measuring techniques, such as photometric, titrimetric, chromotographic or automated-classic analysis, the ion-selective electrode measurement has an impressive list of advantages. The specificity of ion-selective electrodes is not quite as good as that of the glass pH electrode. Interferences vary from minor to major; the literature and manufacturers' data on limitations need to be consulted for each electrode. Ion-selective electrodes are classified according to the type of sensing membrane employed. Solid-state electrodes are made of crystalline membranes and there are scrupulous requirements for the size and charge of the mobile ions within the membrane. The electrode is designed so that the liquid-ion exchanger, used as a sensing element, has a very small positive flow into the process stream.
