[Effect of multivalent cations on the enzymatic determination of glucose with glucose oxidase]

Iron and copper ions, in a concentration greater than 10(-4) M, inhibit the indicator reaction of a glucose oxidase-peroxidase reagent for the enzymatic determination of glucose, when weakly complexing buffers or buffer-free reaction media are used. The addition of EDTA and other complexing agents or, time-dependently, the buffer ions themselves reverse the inhibition to a great extent. The discussed mechanism of inhibition is based on the assumption that the metal ions share in the re-oxidation of the co-enzyme of glucose oxidase.