Hey everyone,

I am working on enzymatic glucose sensing using glucose oxidase. To find the concentration of glucose, we can either do it by measuring the oxygen consumed, or by measuring the hydrogen peroxide produced.

During electrochemical analysis (chronoamperometry) at negative potentials (-0.4V, -0.3V, -0.2V), I saw an increase in current response after I added glucose (see attached graph). I did this experiment in air-saturated TRIS buffer at pH 7. Does this increase in current response indicate that there is less oxygen remaining in the solution after the addition of glucose? (As the oxygen will react with the FADH2 in glucose oxidase to give FAD and hydrogen peroxide).

In other words, higher oxygen conc. in the solution will give more negative current, because there is more oxygen to be reduced. When glucose is added, the oxygen will be consumed by FADH2, resulting in a decrease in oxygen conc. in the solution. Therefore, we are getting less negative current because less oxygen is being reduced?

Any comments will be greatly appreciated. Thanks.