Enzymatic Sensor Using Mediator‐Screen‐Printed Carbon Electrodes

A new glucose sensor was developed using screen-printed ferrocyanide/carbon electrodes. The ferrocyanide is included in the carbon ink of the commercial screen- printed electrode. The immobilization of enzymes glucose oxidase (Gox) and horseradish peroxidase (HRP) were carried out in a very easy way. An aliquot of 10 µL of a Gox/HRP mixture was deposited on the electrode surface and left there until dried (approximately 1 h) at room temperature. The ferricyanide generated enzymatically was detected amperometrically applying a potential of −0.1 V (vs. Ag pseudo reference electrode). The sensor, so constructed, shows a good sensitivity to glucose (−2.12 µA/mM) with a slope deviation of ±0.06 µA/mM and a linear range comprised between 0.05 and 1 mM of glucose, with a limit of detection of 0.025 mM. These sensors show good intersensor reproducibility and a high stability. When they are stored at 4 °C, no significant changes in the slope value of the glucose calibration plot were found after 3 months. Glucose was determined in real samples as honey, blood, drink for babies and glucosed drink with a great accuracy.