The electrochemistry of pyrroloquinoline quinone (PQQ) was examined and the coupling of PQQ with glucose oxidase was studied at different pH values. Optimal interaction between PQQ and glucose oxidase was observed at pH 3.5. Results from these studies enabled construction of PQQ-glucose oxidase-modified enzyme electrodes for the detection of glucose in Ribena blackcurrant juice. The corresponding amperometric determination of glucose was in good agreement with results obtained using commercial enzymatic test kits supplied by Bochringer Mannheim and Sigma Diagnostics.
Loughran, M. G., Hall, J. M., & Turner, A. P. F. (1996). Development of a pyrroloquinoline quinone (PQQ) mediated glucose oxidase enzyme electrode for detection of glucose in fruit juice. Electroanalysis, 8(10), 870-875. https://doi.org/10.1002/elan.1140081004