REDUCTION OF ELECTROOXIDIZABLE INTERFERENT EFFECTS - OPTIMIZATION OF THE APPLIED POTENTIAL FOR AMPEROMETRIC GLUCOSE SENSORS

The selectivity originally anticipated for enzyme-based amperometric e lectrochemical sensors, specifically glucose sensors based on the oxid ation of hydrogen peroxide, has not been achieved due to the oxidation of interfering compounds. These interfering compounds are analytes no rmally present in physiological fluids or tissues that oxidize at the electrode surface and give ''false'' current readings. The effect of l owering the potential applied to a platinum black working electrode wa s studied. In vitro studies showed that lowering the applied potential from +0.60 V to +0.35 V greatly decreased the current due to oxidatio n of acetaminophen, a common interferent, while leaving the current ou tput due to glucose virtually unchanged. In vivo studies revealed that the positive, constant offset observed when comparing the plasma gluc ose concentration to the glucose concentration indicated by an implant ed glucose sensor was greatly minimized by reducing the applied potent ial from +0.60 V to +0.35 V. The offset was thought to be due to the o xidation of interferents. The linearity, magnitude, and stability of t he sensor's in vitro and in vivo response to glucose was unchanged by the reduction in the applied potential.