Chemically modified ion-sensitive field-effect transistors: elimination of the liquid juction potential in a double sensor flow-injection analysis cell

摘要

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