Reduction of electrooxidizable interferent effects: Optimization of the applied potential for amperometric glucose sensors

The selectivity originally anticipated for enzyme‐based amperometric electrochemical sensors, specifically glucose sensors based on the oxidation of hydrogen peroxide, has not achieved due to the oxidation of interfering compounds. These interfering compounds are analytes normally present in physiological fluids or tissues that oxidize at the electrode surface and give “false” current readings. The effect of lowering the potential applied to a plantium black working electrode was studied. In vitro studies showed that lowering the applied potential from +0.60 V to +0.35 V greatly decreased the current due to oxidation of acetaminophen, a common interferent, while leaving the current output due to glucose virtually unchanged. In vivo studies revealed that the positive, constant offset observed when comparing the plasma glucose concentration to the glucose concentration indicated by an implanted glucose sensor was greatly minimized by reducing the applied potential from +0.60 V to +0.35 V. The offset was thought to be due to the oxidation of interferents. The linearity, magnitude, and stability of the sensor's in vitro and in vivo response to glucose was unchanged by the reduction in the applied potential.