CHEMICALLY MODIFIED ION-SENSITIVE FIELD-EFFECT TRANSISTORS - ELIMINATION OF THE LIQUID JUNCTION POTENTIAL IN A DOUBLE SENSOR FLOW-INJECTIONANALYSIS CELL

A flow-through cell was designed that can be used for flow-injection a nalysis with two chemically modified ion-sensitive field-effect transi stors (CHEMFETs) in close proximity. This offers the possibility of a differential measurement without influence of the liquid junction pote ntial. The differential signal of a potassium- and a sodium-selective CHEMFET responded in a Nernstian manner and selectively towards potass ium in an excess (fixed) concentration of sodium. A highly lead-select ive CHEMFET was used in the same flow cell in combination with a potas sium-selective CHEMFET.